Journals >Laser & Optoelectronics Progress
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2012
Volume: 49 Issue 10
29 Article(s)
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Atmospheric Optics and Oceanic Optics
Tropospheric Aerosol Measurements by Lidar in Northern Suburbs of Nanjing
Shi Jianzhong, and Cao Nianwen
The Raman-Rayleigh-Mie lidar (RRML) system in the Nanjing Comprehensive Observation Base of China Meteorological Administration is introduced. In order to get accurate aerosol data, we use the lidar signal from Mie channel of the lidar system to measure the aerosol in the northern suburbs of Nanjing. The extinction proThe Raman-Rayleigh-Mie lidar (RRML) system in the Nanjing Comprehensive Observation Base of China Meteorological Administration is introduced. In order to get accurate aerosol data, we use the lidar signal from Mie channel of the lidar system to measure the aerosol in the northern suburbs of Nanjing. The extinction profiles at different weather conditions (sunny and cloudy) are obtained. The variation of aerosol with time and wind direction is analyzed. The stratus base height and extinction structure are observed. According to experiments in real time, the aerosol loading changes with time in the windy case. The measurement results indicate that lidar can be finely used in dectecting aerosol. Tropospheric aerosol loading varies with wind direction due to the geographic location of Nanjing. The aerosol optical depth in the whole year of 2011 first increased and then decreased and the maximum value occurred in September. The extinction structure in stratus could be symmetric or asymmetric. Aerosol at the boundary layer diffuses downward, at the same time the altitude of boundary layer keeps stable and extinction of aerosol at low-altitude increases. In this process, the optical depth of aerosol from ground to boundary layer remains unchanged..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 100101 (2012)
Development of a New Open-Path Gas Analyzer for Eddy Covariance System
Tian Yongzhi, Liu Jianguo, Kan Ruifeng, and Yao Lu
The fluxes of heat, water and other trace gases are measured directly using eddy covariance method. For eddy covariance measurements, a new calibration-free open-path trace gas analyzer, based on tunable diode laser absorption spectroscopy (TDLAS), is developed and applied for trace gas fluxes in the atmospheric surfacThe fluxes of heat, water and other trace gases are measured directly using eddy covariance method. For eddy covariance measurements, a new calibration-free open-path trace gas analyzer, based on tunable diode laser absorption spectroscopy (TDLAS), is developed and applied for trace gas fluxes in the atmospheric surface layer. By selecting different absorption lines, different trace gases are detected. Carbon diode absorption line (near 4990 cm-1) is taken as an example. The output bandwidth of the new gas analyzer is more than 10 Hz. A comparative experiment is conducted between a reliable commercial analyzer (Li-7500) using non-dispersive infrared (NDIR) gas sensor and our new trace gas analyzer. The collected data demonstrate an excellent qualitative agreement and show that the sensitivity of our gas sensor is about 5×10-7. It is indicated that the fast sampling and high sensitivity meet the requirements of the eddy covariance method. This TDLAS trace gas analyzer is a suitable technique for determining the fluxes of trace gases using eddy covariance method..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2012
- Vol. 49, Issue 10, 100102 (2012)
A New Method for Atmospheric CO2 Balloonsonde Measurement
Feng Lin, Hu Shunxing, Huang Jian, Yuan Ke′e, Shao Shisheng, Xu Zhihai, Cao Kaifa, Meng Xiangqian, Lü Weiyu, Yu Haili, and Zhang Shiguo
A new method is presented for atmospheric CO2 balloonsonde measurement. Based on Beer-Bouguer-Lambert law and non-dispersed infrared (NDIR) technique, an experimental device is designed and developed. A infrared LED is used to produce suitable light source, and infrared LED detectors and a proper electronic circuit desA new method is presented for atmospheric CO2 balloonsonde measurement. Based on Beer-Bouguer-Lambert law and non-dispersed infrared (NDIR) technique, an experimental device is designed and developed. A infrared LED is used to produce suitable light source, and infrared LED detectors and a proper electronic circuit designed are used to transform light intensity into electrical signals in the experimental device. Calibration method for CO2 measurement is also presented. A comparison experiment is carried out for continuous 24 h on ground with EC9820 analyzer. Result shows that measurement error ranges from -10×10-6 to 10×10-6, and standard deviation is 3.76×10-6, which basically satisfies the precision demand for atmospheric CO2 measurement. The feasibility of CO2 measurement has been validated..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 100103 (2012)
Fiber Optics and Optical Communications
Short Cavity Single Frequency Fiber Laser at 1080 nm Based on Highly Yb3+-Doped Phosphate Fiber
Zhang Weinan, Li Can, Feng Zhouming, Yang Changsheng, Xu Shanhui, and Yang Zhongmin
A 1080 nm single frequency fiber laser with a short distributed Bragg reflector (DBR) structure based on a 1.4 cm highly Yb3+-doped phosphate glass fiber is reported. The maximum output power of 90 mW and the slope efficiency of 36.6% are obtained. The output power instability in one hour is less than 0.05%. The side mA 1080 nm single frequency fiber laser with a short distributed Bragg reflector (DBR) structure based on a 1.4 cm highly Yb3+-doped phosphate glass fiber is reported. The maximum output power of 90 mW and the slope efficiency of 36.6% are obtained. The output power instability in one hour is less than 0.05%. The side mode suppression ratio (SMSR) is higher than 69 dB and the measured linewidth is less than 10 kHz. The relative intensity noise is less than -120 dB/Hz for frequencies over 2 MHz..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 100601 (2012)
Research on Remote Gain Unit of Ultra-Long Span Unrepeatered Optical Transmission System
Xu Jian, Fu Chengpeng, Bu Qinlian, Yu Chunping, Jiang Yi, and Huang Liyan
Remote optically pumped amplification technology is widely used in ultra-long span optical transmission system. Based on designed scheme of remote pump technology of the ultra-long span optical transmission system, the relation between gain and noise figure with optical signal-to-noise ratio (OSNR) of system is obtaineRemote optically pumped amplification technology is widely used in ultra-long span optical transmission system. Based on designed scheme of remote pump technology of the ultra-long span optical transmission system, the relation between gain and noise figure with optical signal-to-noise ratio (OSNR) of system is obtained, the structure design of remote gain unit (RGU)from the choice of erbium-doped optical fiber, mirror used, isolator position design is theoretically analyzed and experimentally researched, comparing gain and noise figure of remote gain unit at different schemes. Through the optimization of optical design, the optimal optical structure of remote gain unit is proposed under the conditions of different pump powers and the signal powers. The results show that using low-concentration HE980 erbium-doped fiber, high-reflectivity and low-insertion loss mirror and suitable isolator position, the gain and noise figure of remote gain unit can be obviously improved..
Laser & Optoelectronics Progress
- Publication Date: Aug. 28, 2012
- Vol. 49, Issue 10, 100602 (2012)
Lasers and Laser Optics
Analysis of Chaos Synchronization in New Three-Laser Scheme
Shen Cuili, Ye Huiying, Wei Fupeng, and Li Yong
A new closed-loop dual-directionally chaotic system with three lasers for private message transmission is proposed. A pair of twin semiconductor lasers as responses are routed into chaos by delayed optical feedback, and chaos synchronization to each other is realized by means of optical injection of a common chaotic-drA new closed-loop dual-directionally chaotic system with three lasers for private message transmission is proposed. A pair of twin semiconductor lasers as responses are routed into chaos by delayed optical feedback, and chaos synchronization to each other is realized by means of optical injection of a common chaotic-driving signal generated by a drive laser subject to delayed optical feedback. Appropriate model is built. We investigate the bifurcation and synchronization performance and the effect of internal parameter mismatch, and the results are compared with those of the open-loop system in which the response lasers are not subject to local feedback. The theoretical simulations show thatthe maximum value of cross correlation coefficient between two responses approximates to 1, however, the maximum value of cross correlation coefficient for response and driver is very low. Compared with the open-loop system, the bandwidth of the designed system is widened by about 1.99 GHz, and this system becomes more sensitive to parameter mismatch. So the closed-loop scheme offers a better privacy level..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 101401 (2012)
Mutual Injection Phase Locking of Solid-State Lasers with Corner-Cube Cavity
Yang Zhuo, Cheng Yong, Lu Changyong, Liu Bingqi, and Zhu Mengzhen
Coherent combination of laser arrays is an effective way to achieve high-brightness laser beam. Mutual injection phase locking is a passive way of coherent combination. Theoretical analysis and simulation of the coherent properties of the corner cube are done. The scheme to coherently combine beams from pulsed solid stCoherent combination of laser arrays is an effective way to achieve high-brightness laser beam. Mutual injection phase locking is a passive way of coherent combination. Theoretical analysis and simulation of the coherent properties of the corner cube are done. The scheme to coherently combine beams from pulsed solid state lasers with corner cube cavity is proposed. The experiments to coherently combine two and six beams from pulsed solid state lasers are performed. The output energy is more than 255 mJ with the power combination efficiency of approximately 80% and visibility of about 0.5. The simple structure is efficient to achieve coherent combination of laser beams..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2012
- Vol. 49, Issue 10, 101402 (2012)
LBO Crystal Length on the Efficiency of All Solid-State 473 nm Blue Laser
Li Yeqiu, Liu Yanjuan, Li Yong, and Dai Qin
A compact and stable 473 nm continuous all-solid-state blue laser is reported. Simulation analysis of the relationship between the LBO crystal length and the laser output efficiency is done. An optimal length of 10 mm type Ⅰ phase-matching LBO crystal is chosen. Under the pump power of 3 W, 210 mW of the blue laser at A compact and stable 473 nm continuous all-solid-state blue laser is reported. Simulation analysis of the relationship between the LBO crystal length and the laser output efficiency is done. An optimal length of 10 mm type Ⅰ phase-matching LBO crystal is chosen. Under the pump power of 3 W, 210 mW of the blue laser at 473 nm is obtained. The optical-to-optical conversion efficiency is up to 7%. The fluctuation of laser output power is less than 3%..
Laser & Optoelectronics Progress
- Publication Date: Aug. 30, 2012
- Vol. 49, Issue 10, 101403 (2012)
Measurement of Gas-Liquid Mass Transfer in Microchannel using Microscopic Laser Holographic Interferometry
Ji Xiyan
In order to understand further the gas-liquid two-phase mass transfer process mechanism in microchannel, by using the relationship between stripes and fluid refractive index and that between refractive index and the fluid concentration, the microscopic laser holographic interferometry is used to study the concentrationIn order to understand further the gas-liquid two-phase mass transfer process mechanism in microchannel, by using the relationship between stripes and fluid refractive index and that between refractive index and the fluid concentration, the microscopic laser holographic interferometry is used to study the concentration distributions on the liquid side during the formation of Taylor bubble at the inlet of microchannel. The dimension of microchannel is 100 μm in depth, 2000 μm in width, and 4 cm in length. CO2 is used as gas phase and ethanol is used as liquid phase. The shift of the interference stripes during the absorption is recorded by image acquisition system, and the images are treated by a self-designed digital image processing system. Experimental results show that there is obvious mass transfer during the generation processes of Taylor bubbles, and both the liquid side concentration near the interface and the thickness of concentration boundary layer decrease with the increment of liquid and gas velocities. The results show that, for real-time determination of gas-liquid mass transfer process, microscopic laser holographic interferometry testing system can obtain clear images and satisfactory results in the micro scale channels..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 101404 (2012)
Continuously Tunable and Frequency-Stabilized Laser
Liu Qiang, Zhang Junhai, Zeng Xianjin, Huang Zongjun, and Sun Weimin
The paper proves that dichroic atomic vapor laser lock (DAVLL) can ensure that the laser frequency be locked nonresonantly and adjusted continuously, because cesium magnetometer needs a detecting laser to be locked off-resonantly. The ordinary DAVLL theory is introduced and it is pointed out the simple stabilizing freqThe paper proves that dichroic atomic vapor laser lock (DAVLL) can ensure that the laser frequency be locked nonresonantly and adjusted continuously, because cesium magnetometer needs a detecting laser to be locked off-resonantly. The ordinary DAVLL theory is introduced and it is pointed out the simple stabilizing frequency method is not appropriate due to cesium complicated energy level construction of hyperfine transition. It′s found out that the zero point of frequency discrimination is relative to the intensity of magnetic field. The dependence of zero crossing on the magnetic intensity experimentally measured by the saturated absorption spectrum. The results show that the laser frequency can be locked and adjusted continuously centered at red-detuning 105 MHz relative to the Fg=4→Fe=5 transition with a range of 50 MHz. The frequency stability is about 3 MHz..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 101405 (2012)
Analysis of the Pb Element in Gan Nannavel Orange Based on Laser-Induced Breakdown Spectroscopy
Chen Tianbing, Yao Mingyin, Liu Muhua, Zhou Huamao, and Lin Yongzeng
In the experiments, laser induced breakdown spectra produced by infrared radiation of NdYAG nanosecond laser, are measured by fiber optic spectrometer for navel orange. The characteristic spectral line of PbI 405.78 nm is selected as the analysis of line. By measuring the intensities of the characteristic spectral lineIn the experiments, laser induced breakdown spectra produced by infrared radiation of NdYAG nanosecond laser, are measured by fiber optic spectrometer for navel orange. The characteristic spectral line of PbI 405.78 nm is selected as the analysis of line. By measuring the intensities of the characteristic spectral line with different Pb concentrations. According to relation between the spectral line intensity and concentration the calibration curves are established. The experimental results show that the spectral line intensity increases linearly with the concentration of Pb under the condition of low concentration,and increases nonlinearly with the concentration of Pb under the condition of high concentration in Gannan navel oranges, of which minimal fitting degree (R2) are 0.95 and 0.98, respectively. The experimental results also show that, LIBS can quickly analyse the relative content of the heavy metal element in the fruit sample, and can be applied in the field related to foodstuff safety..
Laser & Optoelectronics Progress
- Publication Date: Aug. 28, 2012
- Vol. 49, Issue 10, 101406 (2012)
Study of Ce:Nd:YAG-KTP OPO Eye-Safe Laser Based on Langasite Electro-Optic Q-Switch
Han Wenjie, Li Hejun, Zhang Wenping, Wu Shuangyang, Dou Feifei, and Hu Yongzhao
A flash lamp pumped Ce3+-Nd3+ double doped YAG crystal water cool laser is devised, in which the La3Ga5SiO14, a novel electro-optic crystal activized by a field effect transistor (FET) fast switch circuit, is used as Q-switch. Based on above fact, steady 1.064 μm laser pulse eradiated at a repetition rate of 20 Hz is rA flash lamp pumped Ce3+-Nd3+ double doped YAG crystal water cool laser is devised, in which the La3Ga5SiO14, a novel electro-optic crystal activized by a field effect transistor (FET) fast switch circuit, is used as Q-switch. Based on above fact, steady 1.064 μm laser pulse eradiated at a repetition rate of 20 Hz is realized. An optical parametric oscillator (OPO) is designed outside the 1.064 μm laser resonant cavity, KTP crystal is employed to actualize optical parametric conversion, based on class Ⅱ non-critical phase matching 1.57 μm eye-safe laser is accomplished. Investigation and test is carried out about the influence of fixing stress of YAG rod to the output of 1.57 μm laser, a concernful phenomenon that double refraction induced by stress can depress the OPO conversion efficiency enormously, is discovered, the reason of efficiency fall is analyzed, the relation curve of equivalent stress and OPO conversion efficiency is presented. The highest OPO conversion efficiency is obtained at the pulse repetition rate of 20 Hz, when 1.064 μm laser pulse energy is 220 mJ, 1.57 μm laser pulse energy is 109.3 mJ, pulse duration is 4.3 ns, beam divergence angle is 8.1 mrad, OPO conversion efficiency reaches 50% nearly, corresponding electro-optic efficiency is 0.96% with an electric injection of 11.3 J, OPO efficiency falls slowly when 1.064 μm laser pulse energy increases much more. The energy stability of the OPO laser is excelled 5% with a smart configuration, environmental applicability including temperature, oscillation, impact etc is tested, engineering application of the OPO laser is realized..
Laser & Optoelectronics Progress
- Publication Date: Aug. 28, 2012
- Vol. 49, Issue 10, 101407 (2012)
Nonlinear Optics
Intensity and Polarization Modulation on Cascaded Frequency Doubling and Electro-Optic Coupling in Periodically Poled Lithium Niobate
Kong Yan, Zhang Xiumei, Su Zhouping, and Gao Shumei
The cascade process of frequency doubling and electro-optic (EO) coupling in a single periodically poled niobate (PPLN) crystal is studied. The original coupling process is disturbed by the introduction of another optical wave (control light). Numerical results indicate that magnitude of three waves and the polarizatioThe cascade process of frequency doubling and electro-optic (EO) coupling in a single periodically poled niobate (PPLN) crystal is studied. The original coupling process is disturbed by the introduction of another optical wave (control light). Numerical results indicate that magnitude of three waves and the polarization of the second harmonic (SH) can be both modulated by adjusting the intensity of control light. This result would be useful when simultaneous frequency doubling and signal tuning are desired..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 101901 (2012)
Optical Design and Fabrication
Structure Optimization of Radiation-Shaped Heat Sink for High Power LED
Li Zhong, Li Yong, Tang Yingge, and Lin Qiaojian
We investigate a radiation-shaped heat sink (RHS) using equivalent thermal resistance model, working temperature measurement and software simulation. The thermal resistance model is based on principles of heat transfer. Two digital thermometers and the Icepak software are utilized to conduct temperature measurement andWe investigate a radiation-shaped heat sink (RHS) using equivalent thermal resistance model, working temperature measurement and software simulation. The thermal resistance model is based on principles of heat transfer. Two digital thermometers and the Icepak software are utilized to conduct temperature measurement and thermal simulation, respectively. The results of the measurement and simulation agree with each other, proving the feasibility and reliability of using Icepak to carry out thermal analysis. In order to decrease the working temperature of the heat sink, controlling variable method is adopted to optimize the number of its fins and the aluminium plate′s diameter and thickness by Icepak, which can serve as a reference for the structure optimization of the RHS..
Laser & Optoelectronics Progress
- Publication Date: Aug. 03, 2012
- Vol. 49, Issue 10, 102201 (2012)
Modeling of LED Reflector Cup Based on Compound Parabolic Concentrator
Wang Le, Zhang Shusheng, and Zhai Jing
The compound parabolic concentrator (CPC) cannot be directly modeled in the TracePro software. According to the characteristics of the TracePro software, the CPC key parameters are analyzed through the mathematical model and the geometric relations among the key parameters are derived. The formulas of CPC parameters inThe compound parabolic concentrator (CPC) cannot be directly modeled in the TracePro software. According to the characteristics of the TracePro software, the CPC key parameters are analyzed through the mathematical model and the geometric relations among the key parameters are derived. The formulas of CPC parameters in TracePro modeling are obtained. Designing CPC as the reflector cup of LED luminaire is convenient for optical simulation and analysis, with which the product development cycle and development costs are reduced. The formula of theoretical calculation is also given, which makes modeling possible in TracePro software. The result shows that LED reflector cup based on the CPC designed by this method can greatly improve the optical efficiency of luminaires, contributing to the development of the LED lighting industry..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 102202 (2012)
Optical Devices
Optimization and Analysis for Submicrometermeter-Scale Silicon Waveguide Optical Phase Modulator
Dong Zhengfang, Zhou Zhen, Wang Kunbo, and Feng Lishuang
The theoretical model of a carrier-injection-PIN-based submicrometer-scale silicon waveguide optical phase modulator is built. The optical and electrical properties of the modulator are analyzed theoretically, and the conditions of single-polarization and single-mode for the submicrometer-scale waveguide are determinedThe theoretical model of a carrier-injection-PIN-based submicrometer-scale silicon waveguide optical phase modulator is built. The optical and electrical properties of the modulator are analyzed theoretically, and the conditions of single-polarization and single-mode for the submicrometer-scale waveguide are determined based on the theoretical model. The effects of structure dimensions and doping conditions on modulation efficiency are discussed emphatically under the single-polarization and single-mode conditions. The analysis shows that modulation efficiency can be improved effectively by reducing slab height, increasing doping concentration, increasing doping depth and reducing distance between the doped regions and the rib edge. The optimized device scheme is presented based on the analysis results. The excellent optical mode overlap with the refractive index change region, together with the submicrometer-scale waveguide, enables the modulation efficiency of 19 rad·V-1·mm-1, the modulation bandwidth beyond 1 GHz, and the advantages of compactness, low voltage and ease of integration..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2012
- Vol. 49, Issue 10, 102301 (2012)
Failure Mechanism of Phosphor Layer for High-Power GaN-Based White-LED
Wu Yanyan, Feng Shiwei, Zhou Zhou, and Wei Guanghua
The appearance of black zone on the surface of white light-emitting diode (LED) with phosphor layer has greatly affected light conversion and extraction. Using micro-area analytical tools such as cutting section, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), the acceleration stress test fThe appearance of black zone on the surface of white light-emitting diode (LED) with phosphor layer has greatly affected light conversion and extraction. Using micro-area analytical tools such as cutting section, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS), the acceleration stress test for current and temperature is carried out and the blacking phenomenon for part of the chip aging surfaces is analyzed. The experimental results show atomic number ratio of C to Si in blackened LED is 13.21, higher than that of the unchanged (8.45). There is a main cause about LED encapsulation failure that organic materials can degrade and carbonize in high temperature and lighting conditions, which is verified. And therefore, lighting effect cannot be ignored. But the chip has nothing to do with the failure. Interface stress induced by the mismatch of the expansion coefficient of the chip and packaging materials, photo-degradation and optic-thermal coupling resulted from long time blue-light illumination make the devices disastrously invalid..
Laser & Optoelectronics Progress
- Publication Date: Aug. 28, 2012
- Vol. 49, Issue 10, 102302 (2012)
Physical Optics
Two-Valley Effect on GaAs Photoconductive Antenna′s Carrier Transport
Zhang Liwei, Shang Liping, Tang Jinlong, Xia Zuxue, and Deng Hu
Photo-carrier transport has great influence on photoconductive antenna (PCA) terahertz electromagnetic wave. In this paper, involved with GaAs material′s two-valley effect, the Drude-Lorentz model is updated, and to some extent, the carrier transport conditions is obtained and compared with the simulation result of claPhoto-carrier transport has great influence on photoconductive antenna (PCA) terahertz electromagnetic wave. In this paper, involved with GaAs material′s two-valley effect, the Drude-Lorentz model is updated, and to some extent, the carrier transport conditions is obtained and compared with the simulation result of classical Diffusion-Drift model. Carrier density is coupled with the finite difference time domain (FDTD) method to simulate terahertz radiation′s time domain waveform which then be compared with THz-TDS′s measurement of the time-domain waveform. The results show that Drude-Lorentz model′s simulation time-domain waveform updated by two-valley effect is more similar with THz-TDS′s measurement waveform. When 14 μm and 34 μm aperture photoconductive antenna irradiated by titanium gem femtosecond laser, with its wavelength of 800 nm, pulse half width of 30 fs, pulse repetition frequency of 75 MHz, average power of 327 mW, the carrier′s transport changes caused by GaAs substrate′s two-valley play a key role in THz radiation..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 102601 (2012)
Numerical Simulation Research on Time Domain Coherent Terahertz Sources Space Power Synthesis
Zhang Yang, Wang Junbo, Deng Hu, and Shang Liping
To get ultra-wideband and large power terahertz waves, ultra-wideband terahertz sources space power synthesis fundamental based on time domain waveform is put forward. Space power synthesis simulated experiment based on multi-channel latency and waveform transform is carried out with standard data, and related data of To get ultra-wideband and large power terahertz waves, ultra-wideband terahertz sources space power synthesis fundamental based on time domain waveform is put forward. Space power synthesis simulated experiment based on multi-channel latency and waveform transform is carried out with standard data, and related data of terahertz wave space power synthesis is obtained. The simulated experiment indicates in physical experiment of ultra-wideband terahertz sources space power synthesis there can be a certain delay from femtosecond laser to leading edge of every photoconductive antenna unit. During optimization design and the fabrication processing of photoconductive antenna, special attention should be paid to decrease the error of rising edge of terahertz..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 102602 (2012)
Reviews
Research Progress of Large-Mode Area Photonic Crystal Fibers
Yi Changshen, Zhang Peiqing, Dai Shixun, Wang Xunsi, Xu Yinsheng, Xu Tiefeng, and Nie Qiuhua
Large mode area (LMA) photonic crystal fibers have characteristis of endlessly single mode and large mode area. These characteristics overcome the limit of high power systems caused by nonlinearity due to the high power density, especially the ultrafast pulse systems. The excellent characteristis of the LMA photonic crLarge mode area (LMA) photonic crystal fibers have characteristis of endlessly single mode and large mode area. These characteristics overcome the limit of high power systems caused by nonlinearity due to the high power density, especially the ultrafast pulse systems. The excellent characteristis of the LMA photonic crystal fibers make them have a subject of enormous interest in areas such as high-power fiber laser, fiber amplifier, high-power energy transmission, and high sensitivity sensor. The research of LMA photonic crystal fiber is reviewed in terms of the characteristic parameters, design methods, applications, and so on. Their development prospects are also discussed..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2012
- Vol. 49, Issue 10, 100001 (2012)
Beam Shaping Technologies for High Efficiency Laser Fabrication
Xia Guocai, Sun Xiaoyan, and Duan Ji′an
Laser has been widely used in the fabrication field due to its special features of high penetrability and intensity. However, certain modifications in space and time domain should be made to meet the high standards in the efficiency and precision of fabrication with laser. Spatial shaping technology is based on the dipLaser has been widely used in the fabrication field due to its special features of high penetrability and intensity. However, certain modifications in space and time domain should be made to meet the high standards in the efficiency and precision of fabrication with laser. Spatial shaping technology is based on the dipodic principle, the diffraction principle and the polarization principle of light. Temporal shaping technology includes the pulse compression technique and the pulse train control technique..
Laser & Optoelectronics Progress
- Publication Date: Jul. 12, 2012
- Vol. 49, Issue 10, 100002 (2012)
Research Progress in Transparent Conducting Films
Liu Xiaofei, Wang Xiaoping, Wang Lijun, Yang Can, and Wang Zifeng
The properties, preparing technique, research status and recent development of the transparent conducting films including metal film, transparent conducting oxide (TCO) film (doped with In2O3, SnO2, ZnO or TiO2), p-type materials and multilayer films are reviewed in detail. Some special transparent conducting film mateThe properties, preparing technique, research status and recent development of the transparent conducting films including metal film, transparent conducting oxide (TCO) film (doped with In2O3, SnO2, ZnO or TiO2), p-type materials and multilayer films are reviewed in detail. Some special transparent conducting film materials are also introduced. Finally, the research direction and application prospect of the transparent conducting films are discussed..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2012
- Vol. 49, Issue 10, 100003 (2012)
Micro-Holographic Data Storage Technology and Its Research Progress
Wan Yuhong, and Tao Shiquan
Micro-holographic data storage is a bit-based volume holographic data storage technology. Localized micro-holograms are recorded at the focus of two counter-propagating beams, and each hologram represents a single bit that is subsequently read out by monitoring the reflectance of a single focused beam. The capacity canMicro-holographic data storage is a bit-based volume holographic data storage technology. Localized micro-holograms are recorded at the focus of two counter-propagating beams, and each hologram represents a single bit that is subsequently read out by monitoring the reflectance of a single focused beam. The capacity can be 1 TB in a CD size disc using micro-holographic data storage technology together with hybrid multiplexing methods. It is easy to develop the compatibility of micro-holographic data storage system with the optical disc storage owing to their similar system structure. The basic concept and theoretical model of micro-holographic data storage are firstly illustrated, and then the research progress is reviewed mainly from the aspects including recording media, multiplexing technology and driving system, its future development is also pointed out..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2012
- Vol. 49, Issue 10, 100004 (2012)
Advances in Ablation Optics of Hard Dental Tissue
Zhan Zhenlin, Zhang Xianzeng, Guo Wenqing, Liu Haishan, and Xie Shusen
The development course of "laser drill" is retrospected, the optical properties of hard dental tissue and the laser-tissue interaction manner and mechanism are summarized. The research advances in the application of laser on hard dental tissues, such as enamel, dentin, calculus and alveolar bone are reviewed.The development course of "laser drill" is retrospected, the optical properties of hard dental tissue and the laser-tissue interaction manner and mechanism are summarized. The research advances in the application of laser on hard dental tissues, such as enamel, dentin, calculus and alveolar bone are reviewed. The fundamental issues of hard dental tissue ablation and its development in the future are described. Hard biotissue ablation with pulsed lasers is widely promising for the applications in dentistry..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 100005 (2012)
Recent Progress on Rare Earth Doped Femtosecond Fiber Lasers
Wang Junli, Lü Zhiguo, and Bo Xiangbao
Generally fiber lasers are classified as two types according to their principles. One is based on nonlinear effect of silica fiber, and the other is based on the simulated emission of rare earth ions which are doped in the optical fiber. the rare earth elements doped in the fiber are always lanthanide series. The develGenerally fiber lasers are classified as two types according to their principles. One is based on nonlinear effect of silica fiber, and the other is based on the simulated emission of rare earth ions which are doped in the optical fiber. the rare earth elements doped in the fiber are always lanthanide series. The development of femtosecond fiber laser is analyzed and the characterstics of several femtosecond fiber lasers are demonstrated. The idea to resolve the present problems of the femtosecond fiber lasers is gave..
Laser & Optoelectronics Progress
- Publication Date: Aug. 28, 2012
- Vol. 49, Issue 10, 100006 (2012)
Brillouin Dynamic Grating and its Applications in Distributed Sensing
Zhu Jing, Tu Xiaobo, Yao Qiong, and Meng Zhou
Brillouin dynamic grating (BDG) based on stimulated Brillouin scattering is a new technology proposed in recent years. It is one of the hot topics in the area of fiber optic commutations and sensing due to its superiorities in separating writing and reading beams, tunability of location and spectra, and high speed recoBrillouin dynamic grating (BDG) based on stimulated Brillouin scattering is a new technology proposed in recent years. It is one of the hot topics in the area of fiber optic commutations and sensing due to its superiorities in separating writing and reading beams, tunability of location and spectra, and high speed reconfiguration over traditional fiber grating technique. It gains much more interest in distributed optical fiber sensing area since it overcomes the limitation of spatial resolution induced by the phonon′s lifetime and it can reach a much higher sensitivity. Current status and advances achieved in BDG are summarized along the technological developing trace. Technologies and applications of BDG based on distributed optical fiber sensing technologies are introduced. Existing problems and future trends are also discussed..
Laser & Optoelectronics Progress
- Publication Date: Sep. 10, 2012
- Vol. 49, Issue 10, 100007 (2012)
Applications of Photoacoustic Spectroscopy in the Field of Modern Biomedicine
Li Li, Xie Wenming, and Li Hui
Photoacoustic spectroscopy technology (PAST) is a new technology for researching material absorption spectra; it has become an important branch in the molecular spectroscopy. As a powerful tool for analysis in the field of modern biomedical, Photoacoustic spectroscopy technology overcomes the influence of the biologic Photoacoustic spectroscopy technology (PAST) is a new technology for researching material absorption spectra; it has become an important branch in the molecular spectroscopy. As a powerful tool for analysis in the field of modern biomedical, Photoacoustic spectroscopy technology overcomes the influence of the biologic tissue′s scatter characteristics, providing an effective and noninvasive way for biomedical materials research, being highly sensitive and without sample pretreatment. The basic principle of photoacoustic spectroscopy technology and the experimental devices are described and the applications of photoacoustic spectroscopy technology in the modern biomedicine are introduced..
Laser & Optoelectronics Progress
- Publication Date: Aug. 20, 2012
- Vol. 49, Issue 10, 100008 (2012)
Scattering
Scattering Property of a Spheric Target Irradiated by Near Field of a Current Element
Li Yingle, Li Jin, Wang Mingjun, and Dong Qunfeng
The expression of near field of a current element in the target coordinate system is obtained and its validity is tested. Then we expand the near field and the scattering field with the spherical vector wave functions. The expanding coefficients are acquired by using the orthogonality among those functions. Their simulThe expression of near field of a current element in the target coordinate system is obtained and its validity is tested. Then we expand the near field and the scattering field with the spherical vector wave functions. The expanding coefficients are acquired by using the orthogonality among those functions. Their simulations and the physical analysis are presented. When the target in this near filed, its scattering field is obtained. Simulations of the obtained results are given. The correctness of the results is demonstrated by the method of moment. It is concluded that when the target exists in the near field, there are respectively the TE wave and the longitudinal wave, and the longitudinal wave is the major one in scattering. The measuring angle θ has a great effect on hte scattering field. This method can be used to research scattering by other antennas such as phase array one as well as the electromagnetic interactions among targets, etc..
Laser & Optoelectronics Progress
- Publication Date: Jul. 20, 2012
- Vol. 49, Issue 10, 102901 (2012)
Ultrafast Optics
Carrier-Envelope Phase Dependence of Ultrafast Multiphoton Processes in Asymmetrical Media
Yang Weifeng, and Song Xiaohong
The carrier-envelope phase (CEP) dependent ultrafast multiphoton processes in polar molecule media is investigated. The conversion efficiency of four-wave mixing can be controlled by the CEP of ultrashort pulses is found. Moreover, the initial CEP of the incident ultrashort pulse propagating in a polar molecule medium The carrier-envelope phase (CEP) dependent ultrafast multiphoton processes in polar molecule media is investigated. The conversion efficiency of four-wave mixing can be controlled by the CEP of ultrashort pulses is found. Moreover, the initial CEP of the incident ultrashort pulse propagating in a polar molecule medium can be "remembered" by the subsequent generated soliton pulse, which provides a new method to measure the CEP of non-amplified few-cycle ultrashort pulse. Furthermore, the physics mechanism of carrier-wave Rabi flopping in asymmetric semiparabolic quantum well (QW) is studied..
Laser & Optoelectronics Progress
- Publication Date: Aug. 28, 2012
- Vol. 49, Issue 10, 103201 (2012)
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