Journals >Chinese Journal of Lasers
Contents
2009
Volume: 36 Issue 2
51 Article(s)
Export citation format
Research Article
Comparative of Coherent Combining and Incoherent Combining of Fiber Lasers
Zhou Pu, Liu Zejin, and Xu Xiaojun
It is an effective approach to obtain high-power laser beam output while maintaining good beam quality by combining multiple fiber lasers. The far-field intensity distribution for coherent combining and incoherent combining with conformal focusing transimitting is numerically calculated, and the effect of phase error, It is an effective approach to obtain high-power laser beam output while maintaining good beam quality by combining multiple fiber lasers. The far-field intensity distribution for coherent combining and incoherent combining with conformal focusing transimitting is numerically calculated, and the effect of phase error, beam jitter, and fill factor is studied in detail to make a contrastive study of coherent and incoherent combining. It is shown that more energy will be encircled in the main-lobe by coherent combining. However, the far-field intensity distribution by coherent combining will be seriously affected by the beam jitter and fill factor of the laser array. And the tolerance on phase error has been improved by using conformal focusing transmitting scheme. For phase error with root-mean-square (RMS) value of π/3, more than 90% energy of the totally coherent combining counterpart will be contained in the target area with radius of 5.6 cm..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 276 (2009)
Experimental Study on Hundred-Watt Output Power High Repetition Rate Narrow Pulse Duration Fiber Lasers
Li Yao, Zhu Chen, Wang Xiongfei, Lin Jixiang, and Zhao Hong
A pulsed fiber laser based on master-oscillator power amplifier(MOPA) architecture is reported. In order to get a high repetition rate, high peak power,and high beam quality laser, a laser diode(LD) pumped acoustic-optic Q-switched Nd∶GdVO4 solid-state laser is used as a seed source. The seed laser with output power ofA pulsed fiber laser based on master-oscillator power amplifier(MOPA) architecture is reported. In order to get a high repetition rate, high peak power,and high beam quality laser, a laser diode(LD) pumped acoustic-optic Q-switched Nd∶GdVO4 solid-state laser is used as a seed source. The seed laser with output power of 2 W is amplified by Yb-doped double-cladding fibers in two stages whose core diameters are 20 μm and 80 μm. At repetition rate of 50 kHz, average output power of 103 W is generated. The highest peak power is up to 162 kW, pulse duration is 12.7 ns,and M2 value is 4.3..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 281 (2009)
Experiment on Beat Frequency between Two Independent Different Types of Laser
Cao Xiangke, He Yao, and Zhang Rongzhu
An experiment on beat frequency between two independent beams generated by two different types of laser was carried out. One is a wavelength tunable semiconductor laser with central wavelength tunable range of 1052.82～1053.12 nm, and the other is a narrow line width fiber laser with wavelength of 1053.10～1053.20 nm. ThAn experiment on beat frequency between two independent beams generated by two different types of laser was carried out. One is a wavelength tunable semiconductor laser with central wavelength tunable range of 1052.82～1053.12 nm, and the other is a narrow line width fiber laser with wavelength of 1053.10～1053.20 nm. The foundamental principle of beat frequency signal detection is introduced, and the experimental setup is established. Stable and repeatable beat frequency signal with a period of approximate 10 ns and amplitude of 4 mV is achieved by high frequency oscillograph after amplified by wide-frequency amplifier.Beamsplitting prism and an F-P cavity sweep interferometer are utilized to achieve real-time frequency alignment which can monitor relative frequency shift and measure beat frequency simultaneously. A scheme of auto alignment through computer control is proposed in case of low laser frequency stability..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 285 (2009)
1 kW High Power Diode Laser with Polarization Coupled by Gran-Tylor Prism
Ding Peng, Cao Yinhua, Su Guoqiang, Chen Hong, Wang Zhiyong, and Zuo Tiechuan
Output laser beam of high power quantum well diode laser is linearly polarized, and Gran-Tayor prism can distinguish two laser beams in vertical polarizing direction by its characteristic of birefringence. If the input beams are in the opposite direction of the Gran-Tayor prism, they will be coupled into one beam. The Output laser beam of high power quantum well diode laser is linearly polarized, and Gran-Tayor prism can distinguish two laser beams in vertical polarizing direction by its characteristic of birefringence. If the input beams are in the opposite direction of the Gran-Tayor prism, they will be coupled into one beam. The experiment takes two 600 W diode laser stacks with 808 nm centre wavelength. The polarizing direction of one beam is changed by a 1/2 wave plate, the other is unchanged, and they are polarization coupled by the Gran-Tylor prism. The laser beam propagates through fast-axis or slow-axis collimating lens, focusing lens (f=100 mm) and slow-axis spherical aberration correcting lens. When the working current is 130 A, the electro optic efficiency is about 43%. Measured with the UFF100 laser beam diagnostics meter, the focal spot is rectangular, the area is 0.547 mm×5.0 mm, the fast-axis beam parameter product is 26.1 mm·mrad, and the highest output power is 1 kW. The laser system works stably..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 290 (2009)
Influence of Powder Mass and Distribution on Output Energy of Pyrotechnically Pumped Laser
Xiao Nan, Jiang Zongfu, Yuan Shengfu, and Hua Weihong
Pyrotechnically pumped laser uses the intense light of pyrotechnic chemical reaction as the pump light source. The mass and distribution of the powder influence the laser character directly. Variety of laser energy was observed when the unity of powder poles changed from 12 to 48. The two distributions of powders were Pyrotechnically pumped laser uses the intense light of pyrotechnic chemical reaction as the pump light source. The mass and distribution of the powder influence the laser character directly. Variety of laser energy was observed when the unity of powder poles changed from 12 to 48. The two distributions of powders were compared. And then the rules of two elements’ influence on laser energy, i.e. the weight of chemical powder in reactions and the distribution of the chemical powder poles are given. Higher laser energy is achieved when 21 to 30 powder poles are used. The two distribution manners of same total poles were compared. The manner that poles concentrate to few wires is better than those to many wires. 1.003 J laser energy is achieved by use of 24 poles divided averagely to 3 series. The energy is 30 times the result obtained in earlier study, and the weight of chemical powder poles is only one fourth..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 294 (2009)
Period Chaos Controlling in a Gain-Modulated Semiconductor Laser by Delay Polarization Feedback
Yan Senlin
Control of chaos in a gain-modulated feedback semiconductor laser is studied via performing the dual-polarizing light. The laser dynamic physical models of the delay feedback orthogonal polarizing light, the π/2-rotated polarization, the synchronous polarizing directional light are presented, respectively. The chaotic Control of chaos in a gain-modulated feedback semiconductor laser is studied via performing the dual-polarizing light. The laser dynamic physical models of the delay feedback orthogonal polarizing light, the π/2-rotated polarization, the synchronous polarizing directional light are presented, respectively. The chaotic laser can be controlled by adjusting the mirror in external optical path to control the delay time of the polarizing light, or conversing one polarizing light at another polarizing direction, or compensating phase of polarizing light via the polarimeter. Numerical results illustrate that the chaotic laser can be controlled to periodic states..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 297 (2009)
Bandwidth and Gain of PPLN based Optical Parametric Amplification with Different Noncollinear Geometries
Liu Tao, Yu Song, Shen Jing, Zheng Yanlei, Huang Shanguo, and Gu Wanyi
The spectral bandwidth and gain of PPLN based optical parametric amplification (OPA) with different noncollinear geometries have been investigated. The spectral bandwidth and gain is determined by expanding the wave-vector mismatch in a Taylor series and retaining terms through second order. The calculation takes into The spectral bandwidth and gain of PPLN based optical parametric amplification (OPA) with different noncollinear geometries have been investigated. The spectral bandwidth and gain is determined by expanding the wave-vector mismatch in a Taylor series and retaining terms through second order. The calculation takes into account the effects of grating period, noncollinear amplification geometry, crystal’s length and pump intensity. The results show the grating period of PPLN and the noncollinear geometry has effects on the spectral bandwidth. The characteristics of gain bandwidth are similar to those of parametric bandwidth; they are all greatly enhanced on the condition of broadband amplification. Compared with the increase of pump intensity, the gain can be effectively improved by increasing crystal′s length, while the grating period and the noncollinear amplification geometry almost have no effect on the gain..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 302 (2009)
A Real-Time Processing System Based on Field Programmable Gate Array for Infrared Image
Luo Fengwu, Wang Liying, Tu Xia, and Chen Houlai
Key technologies such as real-time signal processing algorithms and hardware structure intended for driving a 320×240 infrared focal plane arrays (IRFPA) are presented here. Owing to the response of the IRFPA is instable with time, an adaptive two point correction (ATPC) algorithm was introduced in which the coeffKey technologies such as real-time signal processing algorithms and hardware structure intended for driving a 320×240 infrared focal plane arrays (IRFPA) are presented here. Owing to the response of the IRFPA is instable with time, an adaptive two point correction (ATPC) algorithm was introduced in which the coefficients were updated accoding to a shutter image as the target. In addition, the real-time processing for plateau equalization (PE) is difficult although the infrared image can be enhanced effectively. In this article, PE algorithm was optimized and simplified by a loop-up table in which the size was limited by the maximum and minimum values in the frame. Therefore, the calculating numbers and requirement of memory were reduced greatly. A real-time infrared system structure based on field programmable gate array (FPGA) was introduced, in which two synchronous random access memortes (SDRAM) were used as frame buffer. In this article, the structure of the system and the software realization of the ATPC and PE were described in details. Meanwhile, the infrared images before and after the process of ATPC method were shown here as well as images with different Plateau values. These results suggested that, for a 320×240 IRFPA, the system works well in the 60 Hz frame rate and 50 MHz system clock. Furthermore, the infrared images were improved significantly and the requirement for real signal processing was achieved consequently..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 307 (2009)
Study on Method for Determining Atmospheric Aerosol Type Using Remote Sensing Experimental Data
Hu Fangchao, Wang Zhenhui, Zhang Bing, and Li Junsheng
The Taihu Lake is selected the study area. By collecting water surface spectral data of analytical spectral devices (ASD) by the ship, atmospheric data of CE318 sunphotometer on the shore, and the moderate resolution imaging spectroradiometer (MODIS) image data on the same day, the data were used to get optical propertThe Taihu Lake is selected the study area. By collecting water surface spectral data of analytical spectral devices (ASD) by the ship, atmospheric data of CE318 sunphotometer on the shore, and the moderate resolution imaging spectroradiometer (MODIS) image data on the same day, the data were used to get optical properties of atmosphere in the study area. A method based on measurements for determining the aerosol type is presented. By using the nearly synchronous measurements of the data from surface spectrum and the sunphotometer with the image, using the radiative transfer model 6S (second simulation of a satellite signal in the solar spectrum), and varying the components of the aerosol type, a look-up table (LUT) is made for the radiance on the satellite. When the total relative error of the defined parameter for relative error gets to the least, the aerosol type is decided. It has been used to get the optical characteristics including polarized phase function of the poly-disperse aerosols by the improved Mie code. The aerosol type is used to retrieve the aerosol optical depth (AOD) in Taihu Lake area, and its retrival accuracy has been improved a lot compared to the measured value from CE318. The method and results will be provided for the supporting of the remote sensing applications, such as the atmospheric optical properties, the radiative transfer calculation, the retrieval of AOD, and the atmospheric correction..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 312 (2009)
Analysis of Continuous Phase Plates Applying Position for TIL Facility
Li Ping, Jia Huaiting, Wang Fang, Liu Lanqin, and Su Jingqin
With the designed continuous phase plates (CPP) by improved G-S algorithm, the focal spot shaping ability, 3ω conversion efficiency and near field intensity modulation for two kinds of CPP were analyzed. It included that 1ω CPP can meet focal spot shaping requirement compared to 3ω CPP. With the KDP crystals by “Ⅰ+Ⅱ” sWith the designed continuous phase plates (CPP) by improved G-S algorithm, the focal spot shaping ability, 3ω conversion efficiency and near field intensity modulation for two kinds of CPP were analyzed. It included that 1ω CPP can meet focal spot shaping requirement compared to 3ω CPP. With the KDP crystals by “Ⅰ+Ⅱ” styles, 3ω conversion efficiency is impacted larger when the disarrange angle being larger, and the degree is related with focal spot size; the more 3ω conversion efficiency impacted, the stronger near field intensity modulation will be. The result can instruct CPP application for TIL facility..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 318 (2009)
Impact of Modified Main-Switch on Capillary Discharge Soft X-ray Laser
Zhang Xingqiang, Cheng Yuanli, Wang Qi, and Zhao Yongpeng
The capillary discharge soft X-ray laser scheme is a new way for generating small-size, table-top, high-efficient and cost-effective X-ray laser. In order to obtain stable and high laser energy, it is necessary to optimize parameters related with laser output. The configuration of the main-switch directly determines thThe capillary discharge soft X-ray laser scheme is a new way for generating small-size, table-top, high-efficient and cost-effective X-ray laser. In order to obtain stable and high laser energy, it is necessary to optimize parameters related with laser output. The configuration of the main-switch directly determines the waveform of the main current which in turn influences laser output. By means of the study of three types of main-switch, it shows that the circuit inductance of the modified ring-small disk main-switch supported by parallel metal bars is feasible to achieve appropriate main current. It is also concluded that the average main current and average laser energy are increase by 4% and 31% respectively than those before modification, while the lasing probability is increaseed by 60% than that of the original ring-large disk main-switch supported by circular metal pipe. Furthermore, under condition of larger and stable laser energy output, the modified main-switch still inherits the high-voltage resistance of ring-small disk main-switch supported by circular metal pipe, and keeps laser beam with narrow pulse width..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 324 (2009)
Strong Band Mixing in Bulk GaAs under High Electric Field Investigated by Time-Domain Terahertz Spectroscopy
Zhu Yiming, Zhang Dawei, He Boyong, and Zhuang Songlin
Nonequilibrium transport of carriers in bulk GaAs under very high electric fields is investigated by time-domain terahertz (THz) emission spectroscopy. It is found that the initial peak height of THz emission waveforms (ΔETHz), which are corresponding to the acceleration of electrons in the Γ valley, gradually increaseNonequilibrium transport of carriers in bulk GaAs under very high electric fields is investigated by time-domain terahertz (THz) emission spectroscopy. It is found that the initial peak height of THz emission waveforms (ΔETHz), which are corresponding to the acceleration of electrons in the Γ valley, gradually increases with increasing bias electric fields F0, for F0<50 kV/cm and saturates at ～1 THz above 50 kV/cm. The experimental results show that the effective acceleration mass of electrons under high electric fields significantly increases with increasing fields (30 times at 300 kV/cm than low bias electric fields), most likely due to strong band mixing under very high fields..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 328 (2009)
Effect of Transient Change of Temperature on Large-Aperture Optical Element
Zhang Junwei, Zhou Yi, Zhou Hai, Lin Donghui, Feng Bin, Jing Feng, and Wang Shilong
Transient change of temperature is an important exciting factor which affects the structure stability of large-aperture optical element in the inertial confinement fusion (ICF) driver. Multi-channel high-precision temperature monitoring instrument is adopted to measure the circumstance temperature of large-aperture optTransient change of temperature is an important exciting factor which affects the structure stability of large-aperture optical element in the inertial confinement fusion (ICF) driver. Multi-channel high-precision temperature monitoring instrument is adopted to measure the circumstance temperature of large-aperture optical element in the switchyard of the technical integration line (TIL) for 24 h. The temperature changing curve with time is got. The finite element software is used to build the finite element model for the optical element is built. With the measured temperature as the load, the plane rotation curve of the large-aperture optical element in 24 h is analyzed. During 24 h, the circumstance temperature change is 0.45 ℃, and the maximum rotation angle is 1.12 μrad. The results indicate that the largest rotation of the optic element exceeds the requirement of beam shot change range, but the success ratio of beam shot can be improved by adjusting beam shot time and reducing waiting time between alignment and beam shot..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 333 (2009)
Particles Manipulation in Multi-Plane Using Non-Diffracting Bessel Beam
Liu Bin, Wu Fengtie, and Jiang Xinguang
The intensity profile of the non-diffracting Bessel beams disturbed by an opaque obstacle was studied. The two-dimonsional optical intensities distribution in difference propagation distances was simulated numerically. Second time reconstruction of the Bessel beam was demonstrated, and the relative parameters were measThe intensity profile of the non-diffracting Bessel beams disturbed by an opaque obstacle was studied. The two-dimonsional optical intensities distribution in difference propagation distances was simulated numerically. Second time reconstruction of the Bessel beam was demonstrated, and the relative parameters were measured. The minimum reconstruction distances are 44 mm and 60 mm respectively when the obstacle dimensions are 400 μm and 520 μm. It shows that the smaller the dimension of the obstacle is, the easier the beam reconstruction. The simulation and experimental results show that the obstructed Bessel beam can reconstruct itself in free space, even achieve multi-plane . This result has an important practical significance in multi-plane micro-manipulation..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 379 (2009)
Optical Quantization in All-Optical Analogy-to-Digital Converter Based on Raman Self-Frequency Shift
Liang Rui, Zhou Xiaojun, Li Heping, Liu Yongzhi, and Liu Yong
In this paper, optical-quantization in all-optical analogy-to-digital converter (ADC) has been achieved based on the Raman self-frequency shift in a photonic crystal fiber (PCF) by numerically solving the generalized nonlinear Schrdiger (GNLS) equation, where the split-step Fourier method (STFM) is used. Gauss-shape pIn this paper, optical-quantization in all-optical analogy-to-digital converter (ADC) has been achieved based on the Raman self-frequency shift in a photonic crystal fiber (PCF) by numerically solving the generalized nonlinear Schrdiger (GNLS) equation, where the split-step Fourier method (STFM) is used. Gauss-shape pulse with pulse width of 300 fs and central wavelength of 1550 nm and the PCF with length of 15 m are used in the simulation. The simulating results show that the center wavelength of the Raman soliton varies linear with the peak power of the input pulse between 110 W and 180 W, where 60 nm dynamic shift can be obtained. In this case, 3 bit quantization accuracy can be achieved..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 383 (2009)
Interface Study of Smart Composite Material with Optical Fiber by Single-Fiber Pull-Out Test
Liu Rongmei, and Liang Dakai
Interface forms between the embedded fiber and the composite. Cracks at the interface can initiate final damage. Therefore, the study of the interface between the embedded optical fiber and the matrix is of crucial importance. Single-fiber pull-out test was designed and used to study the formed interface. The value of Interface forms between the embedded fiber and the composite. Cracks at the interface can initiate final damage. Therefore, the study of the interface between the embedded optical fiber and the matrix is of crucial importance. Single-fiber pull-out test was designed and used to study the formed interface. The value of the interfacial shear strength can be obtained by two ways. Studying the relationship between the embedded length of fiber and pull out force is one way. The other way is to find the critical length Lc, at which the fiber was broken instead of being pulled out. A low-range transducer was designed to precisely capture the magnitude of the pulling force. The force transducer was calibrated. It was shown that the output of force transducer was uninfluenced by the load position. The sensitivity of the transducer was 1.91 mV/V. Single-optical-fiber pull-out test results revealed that the coating of the fiber was broken at the boundary between embedded and bare parts, no matter how short it was embedded in the resin. The core and the clad of the optical fiber were pulled out from the coating, which was left inside the resin. Finite element analysis indicated that there was a region of stress concentration near the boundary at the coat. The shorter the embedded length was, the more intense the concentration was. However, the tests indicate that the coating of the optical fiber and the resin are in good imbibitions..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 387 (2009)
Modulation Instability Induced by Cross-Phase Modulation in Case of High-Order Dispersion and Saturable Nonlinearity
Zhong Xianqiong, and Xiang Anping
The combined effects of high-order dispersion and saturable nonlinearity on modulation instability induced by cross-phase modulation of two optical waves are investigated based on the coupled nonlinear Schrdinger equations including saturable nonlinearity and high-order dispersion in optical fibers. And the method of lThe combined effects of high-order dispersion and saturable nonlinearity on modulation instability induced by cross-phase modulation of two optical waves are investigated based on the coupled nonlinear Schrdinger equations including saturable nonlinearity and high-order dispersion in optical fibers. And the method of linear-stability analysis is adopted. The results show that, when the fourth-order dispersion has the same sign as that of the second-order one, a new gain spectral regime called the second gain spectrum which is far away from the zero point may appear. It actually consists of two small spectra which are always linked together. The first gain spectrum has nearly the same peak value as that of the small spectrum close to the zero point of the second gain spectrum. In the other dispersion regimes, the gain spectra consist of only one regime. The existence of the saturable nonlinearity will make the spectral width and the peak gain of every spectral regime increase with the input power before decreasing. That is to say, for every spectral regime, this may lead to a unique value of peak gain and spectral width for two different input powers..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 391 (2009)
New Measurement for Electromagnetic with the Differential Group Delay of Fiber Grating
Peng Hui, Su Yang, and Li Yuquan
A new magnetic field measurement based on the Faraday effect and the measurement of differential group delay (DGD) in fiber grating was proposed.When the magnetic field was applied, the propagation constants of the two circularly polarized light in fiber grating were changed by the Faraday effect, then insulting in theA new magnetic field measurement based on the Faraday effect and the measurement of differential group delay (DGD) in fiber grating was proposed.When the magnetic field was applied, the propagation constants of the two circularly polarized light in fiber grating were changed by the Faraday effect, then insulting in the change of the DGD of fiber grating.The simulations showed the linear relationship between the peak value of DGD and magnetic field in certain range. The influences of fiber grating on the measurement performance were analyzed. The measurement sensitivity was 1.3 ps/T and the smallest magnetic induction is 10-5 T using the optical vector analyzer with precision of 10-5 ps. The experimental results agree well with the theoretical analysis..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 398 (2009)
Study of Wavelength Modulation Absorption Spectroscopy under Large Optic Depth
Wang Yuntao, Cai Haiwen, Geng Jianxin, and Fang Zujie
Linear approximation of Beer-Lambert law is no longer accepted under high optic depth, so that the popular 2nd harmonic detection in wavelength modulation spectroscopy(WMS) becomes invalid. Logarithmic spectroscopy in WMS is compared with the second-to-first harmonic ratio method. The relationship between harmonic signLinear approximation of Beer-Lambert law is no longer accepted under high optic depth, so that the popular 2nd harmonic detection in wavelength modulation spectroscopy(WMS) becomes invalid. Logarithmic spectroscopy in WMS is compared with the second-to-first harmonic ratio method. The relationship between harmonic signal and optical depth as well the resolution of both is studied theoretically. WMS optical fiber methane sensor at 1650 nm are described. The Foureier coefficients of amplitude modulation of laser in logarithmic spectroscopy are achieved, and the factors affecting the resolution of both methods are studied. The results show that signal-to-noise ratio（SNR) with the logarithmic method is 2～3 order larger than that of ratio method..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 403 (2009)
Generation of Entangled Photon Pairs through Photonic Crystal Fiber
Luo Sixing, Yao Li, and Yang Bojun
We demonstrate a high quality and high counting rate source of entangled photon pairs through four-wave-mixing (FWM) by pumping a 40m dispersion-flattened photonic crystal fiber (PCF). This pair of photons, which are called signal/idle wave, is found at 1545 nm and 1555 nm, respectively. The coincidence and accidental We demonstrate a high quality and high counting rate source of entangled photon pairs through four-wave-mixing (FWM) by pumping a 40m dispersion-flattened photonic crystal fiber (PCF). This pair of photons, which are called signal/idle wave, is found at 1545 nm and 1555 nm, respectively. The coincidence and accidental coincidence ratio (C/A) can reach to 8, with the coincidence rate of 1.43 kHz.. The computer results have tallied in general with the experiment. Such a system can be used as the source of quantum key distribution system with a bit error rate less than 6%..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 410 (2009)
Beam Transmission
Transformation Properties of Hermite-Laguerre-Gaussian Beam in Fractional Fourier Transform Plane
Chen Senhui, Zhang Tingrong, and Feng Xiaofang
In order to study the transformation properties of a Hermite-Laguerre-Gaussian (HLG) beam though a fractional Fourier transform (FRFT) system in detail， the analytical expressions for the intensity distribution of HLG beam on the FRFT plane are derived from Collins formula. By using the derived expressions,numerical caIn order to study the transformation properties of a Hermite-Laguerre-Gaussian (HLG) beam though a fractional Fourier transform (FRFT) system in detail， the analytical expressions for the intensity distribution of HLG beam on the FRFT plane are derived from Collins formula. By using the derived expressions,numerical calculation examples have been presented to illustrate its propagation properties. It is shown that apart from the mode indices m,n, the intensity distribution on the FRFT plane depends on the fractional order p and parameter α, the variation with fractional order p and α is periodic,with the periods of 2 and 2π respectively. Furthermore, the beam shape of HLG beam maintains invariable in FRFT plane..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 374 (2009)
Biomedical Photonics and Laser Medicine
Development of 20 kHz Swept Source Optical Coherence Tomography System
Wu Tong, and Ding Zhihua
The self-developed swept source optical coherence tomography (SS-OCT) system is reported. Based on a high speed scanning laser source, the system realizes high speed A-scan rate of 20 kHz from 500 Hz A-scan rate of time-domain OCT. To realize linear calibration of wave number space, a pre-calibration method based on thThe self-developed swept source optical coherence tomography (SS-OCT) system is reported. Based on a high speed scanning laser source, the system realizes high speed A-scan rate of 20 kHz from 500 Hz A-scan rate of time-domain OCT. To realize linear calibration of wave number space, a pre-calibration method based on the SS-OCT system is used. Because of the non-Gaussian spectrum output of the swept source, a method based on window function is used for spectrum reshaping in the spectrum domain. To eliminate the direct current（DC） and auto-correlation term in the interference spectrum, the common-rejection of balanced detection, and a software method of subtract the mean value were used. The axial and lateral resolution of the SS-OCT system achieves 14 μm and 12 μm, respectively. The ranging depth of the SS-OCT achieves 3.9 mm. High speed optical coherence tomography images of finger-pad organism using the SS-OCT system wera obtained..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 503 (2009)
Raman Spectroscopic Study on EC9706 Cells Irradiated by X-Ray with Different Dose
Zhang Guangshui, Chen Changqing, Qi Jian, and Tang Weiyue
The radiation damage in EC9706 cells by X-rays was studied. Laser Raman spectrum was used to analyze the change of structure and content of protein, nucleic acid and fat, while EC9706 cells irradiated by X-rays was cultivated for 24 h. The results show that the peak and frequency shifting are different from spectra of The radiation damage in EC9706 cells by X-rays was studied. Laser Raman spectrum was used to analyze the change of structure and content of protein, nucleic acid and fat, while EC9706 cells irradiated by X-rays was cultivated for 24 h. The results show that the peak and frequency shifting are different from spectra of the controlled dose and reference groups. The peak in the controlled group spectrum vanishes in some dose groups'. The peak at 1114 cm-1 of ν(C-N) in the main chain of protein disappears in all dose group′s, the peak at 895 cm-1 of ν(Dr) only exists in 8Gy group′s, and the peak at 937 cm-1 only exists in 12Gy group’s. In addition, the C=C vibration peak at 1523 cm-1 β-carotenoid combining cell film only exists in 6Gy group′s. The preferable dose of X-rays can be found by analyzing the variety of the above-mentioned peaks in some dose groups'..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 509 (2009)
Holography and Information Processing
Experiment of Wavelength Selectivity of Volume Holographic Wavelength Division Multiplexing Filter
Liu Dong, Wang Dayong, Zheng Xiaodan, Wan Yuhong, Jiang Zhuqing, and Tao Shiquan
In order to investigate the wavelength selectivity of volume holographic gratings, applied as wavelength division multiplexing (WDM) filter, a 532 nm laser was used to record volume holographic gratings with finite size in doubly doped cubic lithium niobate crystal. Gratings of different size ratio were recorded in traIn order to investigate the wavelength selectivity of volume holographic gratings, applied as wavelength division multiplexing (WDM) filter, a 532 nm laser was used to record volume holographic gratings with finite size in doubly doped cubic lithium niobate crystal. Gratings of different size ratio were recorded in transmission configuration one by one and read in orthogonal scheme with a tunable infrared laser working in the optical communication band. The 3 dB bandwidth of wavelength selectivity curves corresponding to the grating size ratio of 4∶3， 4∶2 and 5∶2 were 0.48 nm， 0.45 nm and 0.43 nm respectively. The Bragg central wavelength of each grating is almost the same as theoretical prediction. This indicated that with larger gratings size ratio one can obtain narrower 3 dB bandwidth in the readout of volume holographic gratings. The wavelength selectivity of volume holographic WDM filter can be obviously improved by choosing a suitable grating size ratio and it is possible to meet the requirement of dense WDM..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 413 (2009)
A Naked-Eye Stereoscopic Display System Based on Digital Light Processor
Wu Xiang, Liao Wei, and Liu Jin′gao
This paper proposes a novel method to realize naked-eye stereoscopic display based on DLP. The method we proposed is different from grating method used widely, it based on the DLP image-forming principle, two DMD chips are appllied instead of single DMD. The stereoscopic image pairs are intersected sequentially and proThis paper proposes a novel method to realize naked-eye stereoscopic display based on DLP. The method we proposed is different from grating method used widely, it based on the DLP image-forming principle, two DMD chips are appllied instead of single DMD. The stereoscopic image pairs are intersected sequentially and projected to different orientation by each DMD. To separate the left and right video, lens is used and located before the screen. Left eye and right eye can receive corresponding frame individually. Some experimental results are given to demonstrate the proposed technology at last..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 417 (2009)
Laser Manufacturing
Laser Surface Hardening Using Determined Intensity Distribution
Yu Gang, Wang Henghai, and He Xiuli
Using transformation technology, laser beams with different shape and spatial intensity distribution are gained. Therefore, some required hardened results such as homogeneous hardened layers could be obtained. The quality of laser surface hardening(LSH) is depended strongly on the intensity distribution. Required surfaUsing transformation technology, laser beams with different shape and spatial intensity distribution are gained. Therefore, some required hardened results such as homogeneous hardened layers could be obtained. The quality of laser surface hardening(LSH) is depended strongly on the intensity distribution. Required surface temperature field and hardened layer are formed by special beam intensity of laser hardening. Laser beams applied in surface hardening include Gaussian beam, flat-topped rectangular beam, curved rectangular beam and array spot beam. Inverse method is required to design the intensity distribution profile corresponding to the hardened quality. The trend of LSH with determined intensity distribution is put forward..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 480 (2009)
Algorithm Optimization for Gesture of Workpiece in 5-Axis Laser Quenching of Free Form Surface
Xu Hongwei, Huang Yumei, Yang Xingang, and Li Yan
The orientation of laser quenching tool to the workpiece surface influences the change of temperature field of quenching area, and then influences the uniformity of surface hardness of the workpiece. According to the structure character of 5-axis laser quenching machine, a rule is advanced that the normal vector of theThe orientation of laser quenching tool to the workpiece surface influences the change of temperature field of quenching area, and then influences the uniformity of surface hardness of the workpiece. According to the structure character of 5-axis laser quenching machine, a rule is advanced that the normal vector of the transient laser quenching area must be always perpendicular to the coordinate plane XOY during laser quenching process. The method to determine the optimal workpiece gesture by the normal vectors of two planes determined by four boundary points in the laser quenching area is proposed. The algorithm to ascertain the four points is given. The model is established to assure the optimal workpiece gesture. Genetic algorithm is used to calculate the location angles of C-axis and A-axis for the optimal workpiece gerture. The gesture of workpiece with B splines curved surface is calculated to verify the feasibility of the model..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 487 (2009)
Effects of Laser Pulse Frequency and Scanning Mode on Welding Quality in Soldering by Fiber Laser
Shi Wenqing, Yang Yongqiang, Guo Wei, Wei Guoqiang, and Huang Yanlu
The welding quality is strongly affected by laser pulse frequency and scanning mode in laser soldering. Laser soldering was experimented on copper clad laminate with Sn-Ag-Cu lead-free solder with 100% 12 W power SP-12P fiber pulse laser soldering system, and laser soldering experiment was carried out with different puThe welding quality is strongly affected by laser pulse frequency and scanning mode in laser soldering. Laser soldering was experimented on copper clad laminate with Sn-Ag-Cu lead-free solder with 100% 12 W power SP-12P fiber pulse laser soldering system, and laser soldering experiment was carried out with different pulse frequency and scanning mode. The results show that cavitations occur and oxide film is crushed on the interface between solder and bonding pad under linear scanning mode by 500 kHz laser. The solder is wet and spreads on the bonding pad, and then laser soldering comes true on the copper clad laminate with Sn-Ag-Cu lead-free solder by pulse laser scanning..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 494 (2009)
Structure and Properties of High-Cr Steel Roller by Laser Surface Melting
Li Meiyan, Wang Yong, Han Bin, Han Tao, and Cheng Yiyuan
Microstructure, phase structure, tempering stability and high-temperature wear resistance of laser melted layer of high-Cr steel roller are analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The tests show that after laser treatment the cross section of mMicrostructure, phase structure, tempering stability and high-temperature wear resistance of laser melted layer of high-Cr steel roller are analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The tests show that after laser treatment the cross section of melted surface is divided into melted zone, heat affected zone (HAZ) and the matrix. The matrix consists of martensite and reticular M7C3 carbides. Laser surface melting leads to the complete dissolution of brittle carbides, and the structure of the melted zone is refined highly consisting of austenite and M23C6 carbide particles. The HAZ consists of crypto-crystal martensite, retained austenite and dispersed carbides. Combined effects of grain refining strengthening, solution strengthening and dislocation strengthening lead to the obvious enhancement of tempering stability of laser melted zone and the hardness reaches a peak of 672 HV at 560 ℃ due to secondary hardening. Laser melted layer has excellent high-temperature wear resistance under high-temperature sliding wear test condition..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 498 (2009)
Laser Physics
Laser Ignition Performance of Boron-Potassium Nitrate Composite at Different Oxygen/Fuel Ratio
Shen Ruiqi, Ye Yinghua, Hu Yan, and Wang Zigen
Boron-potassium nitrate is an important energetic material, whose ignition and burning performances depend on the oxygen/fuel ratio closely. The laser ignition of B-KNO3 composites and doped composites by phenolic resin at different oxygen/fuel ratios were experimentally studied, thermodynamically calculated， and thermBoron-potassium nitrate is an important energetic material, whose ignition and burning performances depend on the oxygen/fuel ratio closely. The laser ignition of B-KNO3 composites and doped composites by phenolic resin at different oxygen/fuel ratios were experimentally studied, thermodynamically calculated， and thermally analyzed. The laser ignition process consists of laser ablation, thermal chemical reaction， and combustion. The laser ignition threshold of 50% fire has minimum of 7.6 mJ (B-KNO3:50/50) and 4.05 mJ (B-KNO3-phenolic resin:40/50/5) with the increase of boron fraction from 30% to 70%. The laser ignition delay time decreases with the laser energy density linearly, moreover the composite of lower laser ignition threshold also has shorter ignition delay time. Because of the onset temperature of reaction of B-KNO3 from 556 ℃ to 548 ℃ and released heat from 1.86 kJ/g to 2.21 kJ/g in case of admix of phenolic resin to B-KNO3, its laser ignition sensitivity and ignition delay time becomes higher and shorter respectively..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 338 (2009)
Surface Tension Effects on the Growth and Collapse of Cavitation Bubbles near a Rigid Boundary
He Jie, Liu Xiumei, Lu Jian, and Ni Xiaowu
The growth and collapse of a cavitation bubble near a rigid boundary in liquids with different surface tensions was investigated by two sensitive fiber-optic sensors based on optical beam deflection. The experimental results show that the surface-tension forces slow down bubble growth progress, but speed up bubble collThe growth and collapse of a cavitation bubble near a rigid boundary in liquids with different surface tensions was investigated by two sensitive fiber-optic sensors based on optical beam deflection. The experimental results show that the surface-tension forces slow down bubble growth progress, but speed up bubble collapse process. The influence of the surface tension on bubble expansion is stronger than that on collapse. Increasing surface-tension decreases the maximum and the minimum bubble radii and shortens the oscillation times. Furthermore, the larger the surface tension is, the stronger impact of the high pressure liquid jet will be. That is to say, cavitation erosion is reduced as decreasing the surface tension. These results help to better understand the cavitation erosion and optimize laser parameters in the fields of laser ophthalmology and underwater laser processing..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 342 (2009)
Lasing Characteristic of Soft X-Ray Spike Pumped by Capillary Discharge at Fast Z-Pinch
Zhao Yongpeng, Liu Tao, Xie Yao, Cheng Yuanli, and Wang Qi
Laser spike of soft X-ray pumped by capillary discharge is measured at 25 Pa pressure and 27 ns rise time of the current pulse with X-ray diode (XRD) coated with a gold layer. The characteristic of this laser is studied. The low pressure and the short rise time of the current pulse lead to a fast compression of the plaLaser spike of soft X-ray pumped by capillary discharge is measured at 25 Pa pressure and 27 ns rise time of the current pulse with X-ray diode (XRD) coated with a gold layer. The characteristic of this laser is studied. The low pressure and the short rise time of the current pulse lead to a fast compression of the plasma. In this condition, the laser spike with the duration of 1.6 ns near the peak of the ground light is obtained. The angle of divergence and gain coefficient of the spike at fast Z-pinch are measured. The angle of divergence measured by shifting the pinhole is 5.3 mrad. By changing the length of gain medium, the gain coefficient is measured as 0.45 cm-1 and gain-length product as 8.28. In addition, a monochromator is used and the laser spike about 46.9 nm is observed..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 347 (2009)
Study of Coherent Population Trapping State with a Four-Level System
Li Qiang, Yun Enxue, and Gu Sihong
In order to investigate the characteristics of dichromatic laser in preparing coherence population trapping (CPT) states in CPT atomic clock and CPT magnetometer, thermal 87Rb atoms are sealed with buffer gas in a glass bulb are prepared into CPT states with dichromatic coherent radiation field. We attribute all statesIn order to investigate the characteristics of dichromatic laser in preparing coherence population trapping (CPT) states in CPT atomic clock and CPT magnetometer, thermal 87Rb atoms are sealed with buffer gas in a glass bulb are prepared into CPT states with dichromatic coherent radiation field. We attribute all states without direct interaction with bi-chromatic coherent radiation field as a “leaky trap state”, and describe the system with a simple four-level system. Through solving optical Bloch equations of the four-level system, we have theoretically studied the preparation of CPT states, especially the de-coherent effects by thermal collision on the two ground states of the Λ structure. The results reveal that this de-coherent collision not only decides the rate of prepared CPT states, but also causes the maximal coherence deviating from the equal intensities of bi-chromatic components. A simple expression is given for roughly estimating the influences of de-coherent collision and laser intensity..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 351 (2009)
Parallel Computer Simulation of Photochemical Reactions
Li Hongjian, Dou Yusheng, Tang Hong, and Sun Shixin
The interreaction between laser pulses and molecules is the key point of researching photochemical reactions, it is also an important issue of laser control of chemical reactions. A model for realistic parallel simulations of photochemical reactions induced by an ultrashort laser pulses is developed. In this model, theThe interreaction between laser pulses and molecules is the key point of researching photochemical reactions, it is also an important issue of laser control of chemical reactions. A model for realistic parallel simulations of photochemical reactions induced by an ultrashort laser pulses is developed. In this model, the electrons are coupled to the vector potential of the radiation field through the time-dependent Peierls substitution. The interaction between laser pulses and molecules is unambiguously. The simulation program is realized. It is proved that the simulation program can repeat the experiments of photochemical reactions and provides many details that could not be observed experimentally by comparing the simulations with the experimental results of photodissociation of cyclobutane and C60. The efficiency of the program is improved by parallel design， and tested on super computer system, the result shows that the parallel program can simulate the photochemical reactions high-efficiently and provide information for controlling the photochemical reactions..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 356 (2009)
Theoretical Investigation of Nozzle with Helium Film Injection at the Converge Section in CW DF/HF Chemical Laser
Li Lan, Hua Weihong, Yuan Shengfu, and Jiang Zongfu
About 20% fluorine atoms recombine to fluorine molecules in continuous wave(CW )DF/HF chemical laser’s nozzle, and it is one of the most important factors influencing the bumping efficiency and lasing intensity of lasers. The fluorine atoms loss is caused mainly by wall recombination. Nozzle contour design does not havAbout 20% fluorine atoms recombine to fluorine molecules in continuous wave(CW )DF/HF chemical laser’s nozzle, and it is one of the most important factors influencing the bumping efficiency and lasing intensity of lasers. The fluorine atoms loss is caused mainly by wall recombination. Nozzle contour design does not have an obvious effect on reducing it. Combining the gaseous film cooling used in aerospace realm, a new kind of nozzle is designed by injecting helium film from nozzle’s converge section. The film is estimated to be a separating layer between the main stream and nozzle wall which can reduce fluorine atoms loss, protect the wall, and throat region from ablation. The numerical results show that the protection and frozen efficient are obvious. The helium film occupies part of the stream channel, which influences the main stream’s transportation. The absolute mass flow rate of fluorine atom falls at nozzle exit plane(NEP) if the main stream’s property keep constant. Several methods are presented to improve the design’s inherent shortage..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 362 (2009)
Chemical Kinetics Simulation for H+NCl3+HI Chemical Laser System
Li Liucheng, Duo Liping, and Yang Bailing
In order to optimize the H+NCl3+HI chemical laser system, a Matlab code for chemical kinetics simulations was developed and the process of 生NCl(a1Δ)-I energy transfer chemical laser of the system was simulated using a one-dimensional premixed model. The influences of H, NCl3 and HI initial number densities and their raIn order to optimize the H+NCl3+HI chemical laser system, a Matlab code for chemical kinetics simulations was developed and the process of 生NCl(a1Δ)-I energy transfer chemical laser of the system was simulated using a one-dimensional premixed model. The influences of H, NCl3 and HI initial number densities and their ratios on small signal gain at different temperatures are examined. The optimum NCl3/H and HI/H ratios are determined by scanning computations when the temperature and H number density are fixed. Finally, the influence of H, NCl3 and HI ratios on maximum small signal gain coefficients and gain durations are discussed. It is shown that when temperature is assumed 400 K, initial H number densities are assumed 1×1015 cm-3, 1×1016 cm-3, 1×1017 cm-3, the maximum small signal gain coefficients can reach 2.6×10-4 cm-1, 2.6×10-3 cm-1 and 2.6×10-2 cm-1 respectively. The optimum NCl3/H and HI/H ratios to achieve maximum small signal gain are 45% and 11%, respectively. It is also shown that the optimum NCl3/H and HI/H ratios increase with the temperature, as well as the maximum small signal gain coefficients..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 367 (2009)
Materials and Thin Films
Luminescent Properties of Eu3+ in Nano-Matrix of SiO2
Jiang Dong, Hu Xiaoyun, Miao Zhonghai, Wang Yongqiang, Pan Jing, and Liu Guojing
Eu3+-doped SiO2 matrix materials were prepared by sol-gel technique. The samples were characterized by the modern analysis techniques such as the fluorescence spectrum, atomic force microscope (AFM) and scanning electron microscope (SEM) and so on. The influences of annealing temperature and doping concentration on theEu3+-doped SiO2 matrix materials were prepared by sol-gel technique. The samples were characterized by the modern analysis techniques such as the fluorescence spectrum, atomic force microscope (AFM) and scanning electron microscope (SEM) and so on. The influences of annealing temperature and doping concentration on the luminescent properties were studied systematically, and the luminescence mechanism was investigated. When the films were excited at 258 nm, double peak at 620 nm and 667 nm were observed, which was rarely seen, and at 620 nm the emission intensity reached the strongest，which suggested Eu3+ ions lay in the coordination environment of the lower symmetry. The annealing temperature made great effect on the emission spectroscopy, the luminescence intensity of the film annealed at 900 ℃ was the strongest. With the variations of doping concentration，the distance between Eu3+ and O2- was changed. At the same UV excitation, the outer electron of O2- migrated to the 4f orbit of Eu3+ caused the energy changed，and the spectrum position removed..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 449 (2009)
Characterization of Optical Waveguide in ZnO Crystal Formed by MeV Helium Ion Implantation
Ming Xianbing, Lu Fei, Liu Hanping, Wang Lei, Hou Dongchao, Liu Xiangzhi, and Zhang Ruifeng
The waveguide has been fabricated in z-cut ZnO crystal by 2.0 MeV He+ ion implantation at doses of 2×1016 ion/cm2 at room temperature. The dark modes of the waveguide were measured by the prism-coupling method with the wavelength 633 nm before and after annealing in air. It is found that there is no dark mode afteThe waveguide has been fabricated in z-cut ZnO crystal by 2.0 MeV He+ ion implantation at doses of 2×1016 ion/cm2 at room temperature. The dark modes of the waveguide were measured by the prism-coupling method with the wavelength 633 nm before and after annealing in air. It is found that there is no dark mode after annealing in air，which means that the lattice damage is considerably reduced, and a completely recovery of lattice structure can be expected by further annealing treatment. TRIM ′2003 code was used to simulate the damage profile in ZnO crystal by 2.0 MeV He+ ion implantation, and profile of lattice damage versus depth was obtained. The refractive index profiles of the waveguide were reconstructed using reflectivity calculation method，It is found that a positive change of refractive index happens in the guiding region, and an optical “barrier” of low refractive index is formed at the end of the ion track，and also found that the shape of the refractive-index profile are quite similar to that of the damage distribution, which provides a vivid proof that the lattice damage produced by nuclear collisions should be most responsible for fabricating of waveguide..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 453 (2009)
Properties of Epsilon-Near-Zero Materials and its Potential Application
Wu Zhongyuan, Huang Ming, Yang Jingjing, Yu Jiang, and Peng Jinhui
The interaction of epsilon-near-zero (ENZ) materials with two dimensional parallel-plate waveguide has been analyzed. Electromagnetic wave energy squeezing and supercoupling effects are verified using the full wave simulations. Lower-frequency resonant peak, characteristic peak, higher-frequency resonant peak was obserThe interaction of epsilon-near-zero (ENZ) materials with two dimensional parallel-plate waveguide has been analyzed. Electromagnetic wave energy squeezing and supercoupling effects are verified using the full wave simulations. Lower-frequency resonant peak, characteristic peak, higher-frequency resonant peak was observed by varying the shape of the waveguide filled with ENZ materials. It is shown that the position of lower-frequency resonant peak is dependent on ENZ materials, and the position of higher-frequency resonant peak is dependent on Fabry-Pérot resonances. Red shift of the resonant peak is observed by selective tuning the permittivity of the materials in the supercoupling region, and lower-frequency resonant peak is on the left-hand side of characteristic peak. Based on the properties of ENZ materials, two potential applications for optical sensor and optical power divider are suggested and numerically studied. In the wavelength range of 1.2～2 μm, sensitivity of the optical sensor is Δλ/Δε=100 nm; Insertion loss of the optical power divider is 0 dB at 1.3 μm. Simulating results show that ENZ materials with intriguing electromagnetic properties are favorable for the tailoring optical sensor and power divider, and may have interesting potential applications in optical communication and optoelectronics devices..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 458 (2009)
Photoisomerization and Nonlinear Optical Property of Polyimide Attached with Azobenzene Chromophore Side-Chain
Sun Jianping, and Wu Hongcai
The nonlinear optical polyimide (NLOPI) attached with azobenzene chromophore side-chain is synthesized by diazo coupling reaction of 4-nitrobenzenediazonium tetrafloroborate to poly(amic acid) in 1-methyl-2-pyrrolidone and imidization reaction at 250 ℃ for 2 h. The photoisomerization property of the NLOPI is investigatThe nonlinear optical polyimide (NLOPI) attached with azobenzene chromophore side-chain is synthesized by diazo coupling reaction of 4-nitrobenzenediazonium tetrafloroborate to poly(amic acid) in 1-methyl-2-pyrrolidone and imidization reaction at 250 ℃ for 2 h. The photoisomerization property of the NLOPI is investigated. The effects of the laser reaction time and laser power on the photoisomerization property of NLOPI film are studied. When the NLOPI film is irradiated by the 532 nm YAG laser, the absorption peak of NLOPI at 500 nm decreases with rising the laser power and extending laser reaction time, while the absorption at 360 nm increases steadily. The third-order nonlinear optical property of the nonlinear optical polyimide attached with azobenzene chromophore side-chain was studied by Z-scan technology. On the effect of 532 nm laser, the nonlinear refractive index and nonlinear absorption properties of the NLOPI are all negative, which shows that the NLOPI is self-scattering media. The nonlinear refractive index (n2), nonlinear refractive coefficient (γ), nonlinear absorption coefficient (β) and the third-order nonlinear susceptibility (χ(3)) of the NLOPI are -1.62×10-7 esu, -4.04×10-14 m2/W, 3.98×10-8 m/W and 3.41×10-18 m2/W, respectively..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 462 (2009)
Sensitivity Comparison for Absorption Measurement of Optical Coatings between SurfaceThermal Lens and Photothermal Detuning Techniques
Hao Honggang, Li Bincheng, and Liu Mingqiang
Based on the theoretical configuration optimization, surface thermal lens(STL) and photothermal detuning(PTDT) experiments with a continuous-wave modulated laser beam excitation are performed with highly reflective films coated on BK7 and fused silica substrates. The amplitudes of STL and PTDT signals as a function of Based on the theoretical configuration optimization, surface thermal lens(STL) and photothermal detuning(PTDT) experiments with a continuous-wave modulated laser beam excitation are performed with highly reflective films coated on BK7 and fused silica substrates. The amplitudes of STL and PTDT signals as a function of the modulation frequency are experimentally measured. The sensitivities of STL and PTDT in measuring the weak absorptance of optical coatings are compared. Compared with STL technique, the PTDT technique is experimentally simple and has a higher spatial resolution for absorption mapping of optical coatings, while maintaining the high measurement sensitivity. The experimental results show that for samples with a large temperature coefficient of reflectivity, the PTDT technique can obtain high measurement sensitivity. Agreement is obtained between the experimental results and the theoretical predictions..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 467 (2009)
Preparation and Characterization of ZrO2 Thin Film by Sol-Gel Method
Li Haiyuan, Tang Yongxing, and Hu Lili
ZrO2 sol was prepared by sol-gel process from a solution containing zirconium n-propoxide as precursor, hydrochloric acid, PVP and acetylacetone as complexing agent in ethanol. The characterization of ZrO2 sol and films was analyzed by viscosity, infrared (IR) spectroscopy, refractive index, differential scanning calorZrO2 sol was prepared by sol-gel process from a solution containing zirconium n-propoxide as precursor, hydrochloric acid, PVP and acetylacetone as complexing agent in ethanol. The characterization of ZrO2 sol and films was analyzed by viscosity, infrared (IR) spectroscopy, refractive index, differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The results show that the ZrO2 sol has a good viscosity stability. The influence of PVP on sol-gel stability is little. The refractive index of coatings treated at 500 ℃ is 1.91. The morphology of coatings surface is smooth. The laser induced damage threshold (LIDT) of coating is improved by adding PVP from 19.6 J/cm2 (1064 nm, 1 ns) to 23.3 J/cm2 (1064 nm, 1 ns)..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 472 (2009)
Influences of the Substrate Stress on Element Surface Figure in Vacuum Evaporating Deposition
Zhu Pei, and Zhu Jianqiang
In vacuum evaporating deposition, the surface deformation of the optical elements was primarily affected by the substrate stress redistribution including the gravitational stress and the residual stress before and after deposition. A model was built to analyze the effects of substrate stress, the results proved that anIn vacuum evaporating deposition, the surface deformation of the optical elements was primarily affected by the substrate stress redistribution including the gravitational stress and the residual stress before and after deposition. A model was built to analyze the effects of substrate stress, the results proved that an interaction stress in the substrate-film interface induced by the gravitational stress in the substrate in the vacuum evaporating deposition produced very little deformation of the substrate. Therefore, the irregular deformation of the optical element induced in vacuum evaporating deposition was determined by the residual stress of the substrate mostly. The experimental results show that the irregular deformation of the substrate caused by the residual stress can be eliminated by fine annealing the substrate before being polished..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 476 (2009)
Measurement and Metrology
Application of Mellin Transform in Opto-Electronic Hybrid Target Detection Technology
Chen Yu, Miao Hua, Lang Qi, Zou Xin, and Wang Wensheng
Opto-electronic hybrid joint transform correlator is developed successfully utilizing the Fourier transform feature of lens and adopting key devices such as electrical addressed liquid crystal device (EALCD), which can realize quasi-real-time detection and precise location of targets with cluttered background. ComparedOpto-electronic hybrid joint transform correlator is developed successfully utilizing the Fourier transform feature of lens and adopting key devices such as electrical addressed liquid crystal device (EALCD), which can realize quasi-real-time detection and precise location of targets with cluttered background. Compared to 4f system, it has the advantages of high identification accuracy, fast recognition speed and so on. However, the image information of moving targets collected form image sensor contains various forms of distortion (such as displacement, rotation and scale, etc.), which makes it difficult to realize automatic real-time recognition and tracking of moving targets. In this paper, the method of Mellin transform is proposed. The theory and algorithm of Mellin transform are studied deeply and computer simulation experiments and optical experiments are also conducted with good results. This solved the problem of scale invariable. As an example, the experiment results of aerial images taken at high altitudet are given. The size of target is 150% of the template. Brighter correlation peaks are obtained after Mellin transform. The algorithm has strong pratical application significance in the field of opto-electronic hybrid target detection..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 421 (2009)
Measurement Accuracy Analysis of Thermal Diffusivities Determined by the Photoacoustic Piezoelectric Technique
Gao Chunming, Bi Yanfang, Sun Qiming, Zhou Ying, and Wang Zhanping
Influence of the length and the diffusivities of the samples on measured results and the applicability of the photoacoustic piezoelectric (PAPE) technique have been studied according to a simplified thermoelastic theory of the PAPE method. The PAPE technique based on a simplified thermoelastic theory was proposed. The Influence of the length and the diffusivities of the samples on measured results and the applicability of the photoacoustic piezoelectric (PAPE) technique have been studied according to a simplified thermoelastic theory of the PAPE method. The PAPE technique based on a simplified thermoelastic theory was proposed. The relationship between the amplitude and phase of the PAPE signal and the frequency modulation were confirmed. Simulations were performed to investigate the measurement accuracy of the different materials with the same thickness and the identical materials with different thicknesses. For proving theoretic results the experimental system was developed to research for thermal diffusivities of red copper, aluminum, brass, iron and steel (C: 0.5%) whose thicknesses of is 2 mm. In addition, the thermal diffusivities of aluminum and brass with different thicknesses were also investigated by the experimental system. It shows that the PAPE technique can be employed for the accuracy measurement of the samples of the better heat conductivity properties and the thicker length..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 426 (2009)
An Adaptive Detecting Centroid Method for Hartmann-Shack Wavefront Sensor
Liang Chun, Liao Wenhe, Shen Jianxin, and Zhou Yu
A new adaptive method is given in this paper to detect the centroid of images caught by Hartmann-Shack (H-S) wavefront sensor after analyzing the reason of causing error. This method is based on the self-square arithmetic, Otsu arithmetic, light spots template matching and special threshold method in different sub-areaA new adaptive method is given in this paper to detect the centroid of images caught by Hartmann-Shack (H-S) wavefront sensor after analyzing the reason of causing error. This method is based on the self-square arithmetic, Otsu arithmetic, light spots template matching and special threshold method in different sub-area. It is more accurate and adaptive than general methods. The experimental results show that more available information of light spots are kept through this way, which improves the accuracy of centroid detection and extends the applicability of H-S wavefront sensor..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 430 (2009)
Optical Three-dimensional Profilometry Based on Modulation Ratio
Shao Shuangyun, and Xu Nan
It is difficult to measure a complex object with a deep hole quickly by traditional three-dimensional (3D) profilometry, such as phase measurement profilometry or Fourier transform profilometry. A new 3D profilometry based on fringe modulation ratio is presented and a coaxial measurement system is designed. It is proveIt is difficult to measure a complex object with a deep hole quickly by traditional three-dimensional (3D) profilometry, such as phase measurement profilometry or Fourier transform profilometry. A new 3D profilometry based on fringe modulation ratio is presented and a coaxial measurement system is designed. It is proved that the fringe modulation ration instead of phase can be used to determine the height distribution of the object because the height of a point of the object is proportional to the log value of modulation ratio of the point. A look-up table of height and modulation ratio is established through system calibration. To obtain the height map of the object, a sinusoidal grating pattern is projected onto the surface of a testing object. Two fringe images of the object are captured by CCD at two different positions. Modulation ratio is computed by Fourier analysis and the height of the point can be obtained by look-up table. The proposed 3D measurement technique can perform 3D shape measurement fast without suffering shading problem. The relative error of the measurement of a step with 79.51 mm height is 0.86%. Experimental results demonstrate that the proposed scheme can be useful for 3D shape measurement..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 435 (2009)
Influence of Metal-Coated Mirrors on Measurement Accuracy in Heterodyne Interferometric Ellipsometry
Deng Yuanlong, Li Yuezhi, Wu Yubin, and Xu Gang
A transmission ellipsometer with the configuration of heterodyne interferometer and two acousto-optical modulators was investigated. A single layer of indium tin oxide on a glass substrate was measured, and the measurement errors of the sample thickness and refractive index range up to 8 nm and 7%, respectively. The inA transmission ellipsometer with the configuration of heterodyne interferometer and two acousto-optical modulators was investigated. A single layer of indium tin oxide on a glass substrate was measured, and the measurement errors of the sample thickness and refractive index range up to 8 nm and 7%, respectively. The influence of the elliptic polarization due to metal-coated mirrors on measurement accuracy was analyzed with Jones vector method. The error only produced by the depolarization effect of metal-coated mirrors can be eliminated just by removing the sample out of the configuration. However, the calibration does not work to the error resulted from the misorientation and the depolarization effect. The calculation shows the error of sample thickness measurement is 4 nm, and the error is approximately linear with the orientation error and independent of the film parameters..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 439 (2009)
Normalization of Autocorrelation Function for Multiple-tau Photon Correlator
Cheng Yanting, Shen Jin, Liu Wei, Sun Xianming, and Yang Yan
A reduced symmetric normalization procedure was presented to reduce the requirement for hardware channels, which needs only one monitor channel in each linearity module. Theory analysis proves that the standard deviation of the reduced symmetric normalization approximates to that of the symmetric normalization and far A reduced symmetric normalization procedure was presented to reduce the requirement for hardware channels, which needs only one monitor channel in each linearity module. Theory analysis proves that the standard deviation of the reduced symmetric normalization approximates to that of the symmetric normalization and far smaller than that of the standard normalization at large delay time. Measurements with polystyrene particles of 90 nm, 1000 nm and 90 nm mixed with 1000 nm show superiority of both symmetric and reduced symmetric normalization over standard normalization. Calculated average standard deviation of standard normalization estimator is 2.5 to 3.5 times larger than that of the symmetric and reduced symmetric ones while the maximum deviation is 4.5 to 8.5 times. Reduced symmetric normalization achieves high statistical accuracy at the expense of obviously reduced additional monitor channels compared with symmetric normalization in multi-tau photon correlator..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 444 (2009)
Reviews
Research on Key Issues of Laser Welding of Dissimilar Metal
Yu Gang, Zhao Shusen, Zhang Yongjie, He Xiuli, and Pang Ming
Advanced engineering structures require dissimilar metal jointing. Laser welding has such merits as high energy density, high depth-to-width ratio, narrow heat-affected zone and limited shape-deformation. Therefore, it becomes one of the effective approaches for jointing dissimilar metal combination. The procedure of lAdvanced engineering structures require dissimilar metal jointing. Laser welding has such merits as high energy density, high depth-to-width ratio, narrow heat-affected zone and limited shape-deformation. Therefore, it becomes one of the effective approaches for jointing dissimilar metal combination. The procedure of laser welding for dissimilar metal is very complex.There are some key issues about laser welding mechanism, for instance, thermal-physical material properties, melt pool dynamics, melt-condensation mechanism, formation of welding defects and residual stress. The progress and present research of experimental and numerical simulation about these issues are discussed. On this basis, some problems of laser welding of dissimilar metal materials are put forward..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 261 (2009)
Research and Progress of Silicon Luminescence
Zhang Rongjun, Chen Yiming, Zheng Yuxiang, and Chen Liangyao
The bottle-neck of microelectronics and the demand of the development of information technology have accelerated the research on optical information processing and optoelectronic integration on Si-based material. The success of high-quality Si-based light sources will make a great impact on optoelectronic and informatiThe bottle-neck of microelectronics and the demand of the development of information technology have accelerated the research on optical information processing and optoelectronic integration on Si-based material. The success of high-quality Si-based light sources will make a great impact on optoelectronic and information industry. Limited by indirect band structure, nature silicon has very low light-emission efficiency, which slows down the application of Si-based light sources. Several approaches have been proposed to obtain silicon luminescence, including porous silicon, silicon nanocrystals, Er3+-doped silicon nanocrystals and stimulated Raman scattering. Various approaches of silicon luminescence research in recent years are reviewed and the characteristic and achievement of different approaches are introduced. It is believed that breakthrough in Si-based light sources will be made and new technology revolution will be started in the near future by the development of device manufacture and the improvement of light-emission efficiency of silicon..
Chinese Journal of Lasers
- Publication Date: Mar. 31, 2020
- Vol. 36, Issue 2, 269 (2009)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20