Contents
2004
Volume: 24 Issue 7
32 Article(s)
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Research Article
Fiber Optics and Optical Communications
Non-Zero Dispersion-Shifted Optical Fibers with Low Nonlinearity for Large Capacity and Long-Haul Transmission SystemJiang
Xiaoqiang, and Wang Ruichun
A non-zero dispersion-shifted fiber with core-depressed profile for large capacity and high bit rate backbone network and metropolitan area network is designed and fabricated by plasma chemical vapor deposition (PCVD) process. The designed fiber has the effective-core-area of more than 95 μm2 and the dispersion of abouA non-zero dispersion-shifted fiber with core-depressed profile for large capacity and high bit rate backbone network and metropolitan area network is designed and fabricated by plasma chemical vapor deposition (PCVD) process. The designed fiber has the effective-core-area of more than 95 μm2 and the dispersion of about 9 ps/(nm·km) at 1550 nm, which can suppress the nonlinearity on the transmission system effectively. Meanwhile, the attenuation at 1550 nm is reduced to around 0.21 dB/km, and the splice loss with conventional single mode fiber is less than 0.11 dB while keeping the good bending performance (bending loss is less than 0.02 dB/km on the wavelength range from 1460 nm to 1625 nm with 60 mm bending diameter and 100 turns). The fiber also has a low dispersion slope of less than 0.065 ps/(nm2·km) and a low polarization mode dispersion (PMD) of less than 0.05 ps·km-1/2. Furthermore, the fiber can be used on the S-band (1460～1530 nm), C-band (1530～1565 nm) and L-band (1565～1625 nm) for wavelength division multiplexing (WDM) system because the zero-dispersion wavelength is shifted to lower than 1430 nm..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 893 (2004)
Research on the Characteristics of Long-Period Fiber Grating Ultraviolet-Written by Amplitude Mask
Zheng Kai, Pei Li, and Jian Shuisheng
The refractive-index distribution function of long-period fiber grating (LPG), which is ultraviolet-written by amplitude mask, is a rectangular wave in the core region. The theoretical method is presented to analyze the characteristics of LPG with the rectangular-index modulation. Here, the weakly guiding scalar approxThe refractive-index distribution function of long-period fiber grating (LPG), which is ultraviolet-written by amplitude mask, is a rectangular wave in the core region. The theoretical method is presented to analyze the characteristics of LPG with the rectangular-index modulation. Here, the weakly guiding scalar approximation and coupled-mode theory based on the three-layer step-index optical fiber are used. The approximate numerical method to deal with the coupled-mode equations is presented in detail and the rationality of the method is given. The transmission spectra of LPG are numerically calculated by using the mathematical software, Matlab. It's found that the transmission spectra of LPG with the rectangular-index modulation are not the linear superposition of its cosine gratings' spectra. The effect of the structural parameters of gratings, such as ambient refraction index, the radii of fiber cladding and the duty cycle of fiber grating, on the transmission spectra of LPG with the rectangular-index modulation is analyzed. Furthermore, the response of double-resonant peak position of a single cladding mode to the parameters of gratings is studied..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 902 (2004)
Study on a Temperature-Insensitive Arrayed Waveguide Grating
Zhu Daqing, and Xu Zhen'e
A new type of temperature-insensitive arrayed waveguide grating (AWG) was studied. Hybrid material waveguide structure in which polymer material was spun on the silica core was adapted in this temperature-insensitive arrayed waveguide grating to change the characteristic of the waveguide and then reduce the sensitivityA new type of temperature-insensitive arrayed waveguide grating (AWG) was studied. Hybrid material waveguide structure in which polymer material was spun on the silica core was adapted in this temperature-insensitive arrayed waveguide grating to change the characteristic of the waveguide and then reduce the sensitivity of the arrayed waveguide grating. Two kinds of structure that were the three-layer structure and the four-layer structure were studied by theoretical and finite difference methods. The temperature characteristics of this arrayed waveguide grating were calculated. The simulation results showed that when temperature change was 0～50 ℃, the maximum wavelength shift of the temperature-insensitive arrayed waveguide grating was less than 0.03 nm, which was less than 4% of that of the ordinary arrayed waveguide grating..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 907 (2004)
Propagation Constant Solution for Large Core and High Numerical Aperture Step-Index Multimode Optical Fiber
Yang Chun, and Xia Zhichao
Overflow of Bessel functions in numerical solution of characteristic equation with double-precision for large-core and high numerical aperture optical fibers is circumvented by evaluating the ratio of the nth order to the (n-1)th order modified Bessel functions of the second kind using a small argument approximation anOverflow of Bessel functions in numerical solution of characteristic equation with double-precision for large-core and high numerical aperture optical fibers is circumvented by evaluating the ratio of the nth order to the (n-1)th order modified Bessel functions of the second kind using a small argument approximation and by evaluating the ratio of nth order to the (n-1)th order Bessel function of the first kind using Lentz-Thompson method. The evaluation error of the two methods is not larger than the minimum value of the floating-point system used. Characteristic equations of multimode silica optical fiber and large core polymer optical fiber are solved using this algorithm and compared with commercial optical software (IFO-Grating) from Optiwave Corp. The results for the silica optical fiber are good agreement with the commercial software. Authors' algorithm has solved all guided modes for the large core optical fiber and results for the guided modes with angular mode number smaller than 70 are same to that of IFO-Grating, but IFO-Grating failed to solve the eigenvalue for guided modes with angular mode number larger than 70..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 957 (2004)
The Study of Time/Frequency Encoding Optical Code Division Multi-Access Communication with Bragg Gragting Arrays
Fu Xiaomei, Yu Jinlong, Li EnbangZ, hu Depeng, Li Yanan, Dai Jufeng, and Yang Enze
Optical code-division multiple-access system, usually known as OCDMA, can provide very attractive features, such as asynchronous access, privacy and security in transmission, ability to support variable bit rate and scalability of the network. A time/frequency encoding/decoding OCDMA system with high quality Bragg gratOptical code-division multiple-access system, usually known as OCDMA, can provide very attractive features, such as asynchronous access, privacy and security in transmission, ability to support variable bit rate and scalability of the network. A time/frequency encoding/decoding OCDMA system with high quality Bragg grating arrays is developed, and transmission rates up to 1.4 Gb/s per user can be achieved. The effects of data rate on the performance of the system are studied theoretically and experimentally. It is proved that even if the data rate is beyond the critical value determined by the distance between Bragg gratings essential for the prevention of code overlapping, the performance of the system can still be satisfying，when the user number is lower than (3/2) times of Ps (pulse number of time in a code) or the code length is larger than 289, the system's error rate will not increase obviously as the data rate exceeds the critical value..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 961 (2004)
Instrumentation, Measurement and Metrology
Novel Connection Method Based on Virtual Cylinder for Three-Dimensional Surface Measurement
He Haitao, Guo Hongwei, Yu Yingjie, and Chen Mingyi
The multi-view (i.e. multi-aperture) overlapping scanning connection technique in cylindrical coordinates is mainly used in connecting measured surface of quasi-rotating objects. It comes into difficulty in surface measurement of object with non-single revolving axis, or whose quasi-revolving axis is comparatively far The multi-view (i.e. multi-aperture) overlapping scanning connection technique in cylindrical coordinates is mainly used in connecting measured surface of quasi-rotating objects. It comes into difficulty in surface measurement of object with non-single revolving axis, or whose quasi-revolving axis is comparatively far from the coordinates axis. A novel connection method is presented on the basis of the principle of the virtual cylinders to solve this problem. This extended connection method on the basis of the virtual cylinders for three-dimensional shape measurement is described, the algorithms how to calculate the approximative radius of the virtual cylinders and the coordinates of its revolving axis are given, and the coordinates translation formula is deduced based on the virtual cylinders. The accuracy of this method has been theoretically verified by computer simulation. And the experimental measurement result of an automobile headlamp reflector reassures experimentally that the method is effective and feasible for three-dimensional complex shape connection, especially to obtain the connected surface tested from different views..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 978 (2004)
Lasers and Laser Optics
The Steady-State Mean Normalized Intensity Fluctuation in a Single-Mode Laser
Cheng Qinghua, Cao Li, Wu Dajin, and Wang Jun
Using the linear approximation method, the steady-state mean normalized intensity fluctuation is calculated after input signal in a single-mode laser system driven by pump noise and quantum noise with cross-correlation between the real and imaginary parts. The influences on the steady-state mean normalized intensity flUsing the linear approximation method, the steady-state mean normalized intensity fluctuation is calculated after input signal in a single-mode laser system driven by pump noise and quantum noise with cross-correlation between the real and imaginary parts. The influences on the steady-state mean normalized intensity fluctuation are analyzed by quantum noise with cross-correlation coefficient between the real and imaginary parts, the intensities of the quantum and pump noise, the amplitude and frequency of input signal and the net gain. It is found that the statistic fluctuation of laser field is smaller in the case of the weaker quantum noise cross-correlation between the real and imaginary parts, smaller noises, far from threshold, smaller amplitude and higher frequency of the signal..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 912 (2004)
Compensation of Medium Dispersion by the Spatially Induced Group Velocity Dispersion
Yang Zhenjun, Lu Guangshan, and Hu Wei
The propagation characteristic of ultrashort pulsed Bessel light beam in dispersive medium is studied. The spatially induced group velocity dispersion (SIGVD) can be used to compensate the dispersion of medium. Diffraction-free and quasi-dispersion-free pulsed beams, similar to a spatiotemproal soliton, can be producedThe propagation characteristic of ultrashort pulsed Bessel light beam in dispersive medium is studied. The spatially induced group velocity dispersion (SIGVD) can be used to compensate the dispersion of medium. Diffraction-free and quasi-dispersion-free pulsed beams, similar to a spatiotemproal soliton, can be produced in a dispersion medium. The numerical simulation results have confirmed the existence of this soliton-like electromagnetic wave. After considering the finite aperture of Bessel beam and the high-order dispersion, the diffraction-free and dispersion-free propagation can only be achieved in a finite distance. The effect of high-order dispersions would become weaker if the longer light pulses are selected. Within the distance shorter than the diffraction distance, the SIGVD describes accurately the dispersive compensation and evolvement of the pulsed beam..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 916 (2004)
Study on a Fiber Ring Laser with Unidirectional Operation without Isolator
Sun Guoyong, Qu Ronghui, Fang Zujie, and Wang Xiangzhao
An erbium-doped fiber ring laser with unidirectional operation without optical isolator has been investigated theoretically and experimentally. The fiber ring laser cavity is only composed of two couplers and built in such a way that it offers a higher counterclockwise over clockwise circulating gain ratio, which is stAn erbium-doped fiber ring laser with unidirectional operation without optical isolator has been investigated theoretically and experimentally. The fiber ring laser cavity is only composed of two couplers and built in such a way that it offers a higher counterclockwise over clockwise circulating gain ratio, which is strongly dependent on coupling coefficients of the two couplers. The optical fields propagating in the two directions suffer from different losses. As a consequence, the laser oscillation appears in a quasi-unidirectional form without isolators. So, the structure of the fiber ring laser is simplified, eliminating the insertion loss arising from the isolator and decreasing the cost. Two 3 dB couplers are used in the experiment, in which the result shows that on and above the threshold of pump power, there is a difference in the output power of 17 dBm between two contrary directions, basically realizing the unidirectional operation of the fiber laser..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 922 (2004)
104 W Laser Diode-Pumped Intracavity Frequency-Doubled Nd∶YAG Green Light Laser
Xu Degang, Yao Jianquan, Guo Li, Zhou Rui, Zhang Baigang, Ding Xin, Wen Wuqi, and Wang Peng
An average 104 W green beam operation by intracavity frequency doubling of Nd:YAG laser, which is pumped by eighty 20 W high-power laser diodes is reported. A type Ⅱ phase matched KTP crystal (=23.6°,θ=90° under the condition of 27 ℃，its size is 7 mm×7 mm×10 mm) is applied for frequency doubling ofAn average 104 W green beam operation by intracavity frequency doubling of Nd:YAG laser, which is pumped by eighty 20 W high-power laser diodes is reported. A type Ⅱ phase matched KTP crystal (=23.6°,θ=90° under the condition of 27 ℃，its size is 7 mm×7 mm×10 mm) is applied for frequency doubling of Nd∶YAG laser. The length of resonator is 530 mm. The KTP crystal is placed in the special cooling device. Under the pumping current of 18.3 A, KTP crystal is cooled to 4.5 ℃. A maximum green power of 104 W was generated at 20.7 kHz repetition rate and 132 ns pulse width when pumping current of laser diodes is 18.3 A, leading to 10.2% of optical-optical conversion efficiency..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 925 (2004)
A Novel Structure L-Band Erbium-Doped Fiber Laser
Zhang Hao, Yu Ling, Yang Shiquan, Liu Yange, Liu Lihui, Xiao Chunxian, Xiong Lingyun, Yuan Shuzhong, and Dong Xiaoyi
A novel structure L-band erbium-doped fiber ring laser is demonstrated. The ring cavity is constituted by erbium-doped fiber (EDF) as the gain medium, a 980 nm laser diode as the co-pumping source, a polarizer and a polarization controller as the L-band wavelength selective device. To be recycled, the backward amplifieA novel structure L-band erbium-doped fiber ring laser is demonstrated. The ring cavity is constituted by erbium-doped fiber (EDF) as the gain medium, a 980 nm laser diode as the co-pumping source, a polarizer and a polarization controller as the L-band wavelength selective device. To be recycled, the backward amplified spontaneous emission (ASE) was routed to the input of EDF by an optical circulator. The lasing threshold is approximately 23.87 mW, the output laser power reaches 6.34 mW and the slope efficiency comes up to about 8.05% when pumping power is set to 103 mW. Compared with the laser without utilizing backward ASE, it is apparent that the performance of L-band fiber ring laser has been much improved. When inapposite length EDF was used, no laser output was obtained without utilizing backward ASE; whereas laser with the threshold power of about 88 mW has been achieved with backward ASE compensation. Thus the above conclusion is well proved..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 929 (2004)
Materials
A Study of Voltage-Dependent Electric-Control Birefringence of Liquid Crystal
Wang Wei, Li Guohua, and Xue Dong
The peculiarity of nematic liquid crystal (LCBL-009) electric-control birefringence is studied. The simple and precise polarized light interference method is employed to measure the birefringence of liquid crystal. When wavelength of the incident light is 630 nm, transmissivity curve of LC is measured as the functions The peculiarity of nematic liquid crystal (LCBL-009) electric-control birefringence is studied. The simple and precise polarized light interference method is employed to measure the birefringence of liquid crystal. When wavelength of the incident light is 630 nm, transmissivity curve of LC is measured as the functions of the effective value and frequency of AC voltage by using Shimadzu UV-3101 PC spectrometer. After analysing the experimental result, electric-control birefringence of LC was obtained. The electriccontrol birefringence of LC is single order exponential falling with the increase of effective value of voltage and linear falling with the increase of frequency of voltage in definitive domain. The obtained result is usefull for the design and manufacturing, application of LC device..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 970 (2004)
Effect of Alkaline-Earth Metal Ions on Removing OH Groups from Erbium-Doped Phosphate Glasses
Yang Gangfeng, Deng Zaide, Feng Zhouming, Yin Bing, Ying Tingzhao, and Jiang Zhonghong
The effects of the type and concentration of alkaline-earth metal ions are systemically investigated on removing OH groups of erbium-doped phosphate glasses, by using fluoresent lifetime of erbium-doped phosphate glasses varying with OH concentration. The experimental results indicate that bubbling dry O2 and CCl4 gaseThe effects of the type and concentration of alkaline-earth metal ions are systemically investigated on removing OH groups of erbium-doped phosphate glasses, by using fluoresent lifetime of erbium-doped phosphate glasses varying with OH concentration. The experimental results indicate that bubbling dry O2 and CCl4 gases into glasses could effectively reduce OH groups. The OH groups were removed rapidly at the beginning, then slowed down with increasing bubbling time, and finally, the removing and absorbing of OH groups of erbium-doped phosphate glasses reached equilibrium. It should be mentioned here that the fluorescence lifetimes at the same bubbling time decrease with increasing alkali-earth ions radius in the order of Ca>Sr>Ba. The erbium-doped phosphate glasses which have a high alkaline-earth metal ions concentration, exhibit a short fluorescence lifetime and a strong reabsorbing ability of OH- groups after stopping bubbling gas..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 973 (2004)
Medical Optics and Biotechnology
Monitoring Osmotical Agents Induced the Change in Optical Properties of Mouse Skin
Cen JianZhu Dan, Luo Qingming, and Zeng Shaoqun
A double integrating sphere system was developed to investigate the effect of the osmotic agent of glycerol on the optical properties change of mouse skin. The results showed that the reduced scattering coefficient of mouse skin reduced, and the absorption coefficient increased when rate skin was immerged during the inA double integrating sphere system was developed to investigate the effect of the osmotic agent of glycerol on the optical properties change of mouse skin. The results showed that the reduced scattering coefficient of mouse skin reduced, and the absorption coefficient increased when rate skin was immerged during the initial 25 min, and then the optical properties of rat skin approached to constants. The changes in absorption and scattering parameters resulted in reduce of the effective attenuation coefficient. This study provides a new method to investigate the control of optical properties of tissu. It is important for optical imaging of tissue..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 873 (2004)
Scattering Phase Function of Biological Tissue and the Properties of Second-Order Optical Parameter
Liu Ying, Zhang Xiaojuan, and Hu Youzhou
Biological tissue is a complex medium, only anisotropic factor g is not enough to describe its scattering properties in many situations. The scattering properties of tissues can be characterized with parameters g and γ, where γ is a quantity that relates to second-order moment g2 of phase function, and shows the relatiBiological tissue is a complex medium, only anisotropic factor g is not enough to describe its scattering properties in many situations. The scattering properties of tissues can be characterized with parameters g and γ, where γ is a quantity that relates to second-order moment g2 of phase function, and shows the relationship between g2 and first-order moment g1. Some phase functions used to characterize the tissues at present and their second order parameter γ are studied, and the influence of phase function choice on γ measuement is discussed. The results demonstrate that γ is a measurable tissue quantity. These researches have teoretical significame and are practically valuable to consummate diffuse scattering theory and measure high-order parameter γ of tissues and other optical parameters..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 877 (2004)
Nonlinear Optics
Optical Voltage Sensing Based on Periodically Poled LiNbO3 by Second Harmonic Generation
Chen Hongyun, Sang Minghuang, Chen Yuping, Chen Xianfeng, and Zou Daowen
A novel method of optical voltage sensing based on second harmonic generation in periodically poled LiNbO3 (PPLN)is proposed. The influences of length and duty ratio of PPLN on the performance of optical voltage sensor are discussed. The simulated results show that when the length is fixed, the highest sensitivity can A novel method of optical voltage sensing based on second harmonic generation in periodically poled LiNbO3 (PPLN)is proposed. The influences of length and duty ratio of PPLN on the performance of optical voltage sensor are discussed. The simulated results show that when the length is fixed, the highest sensitivity can be obtained when the duty ratio is equal to 0.3 or 0.7; and voltage measurement range reaches maximum as the duty ratio approaches 0.5; the sensitivity increases and the sensing voltage measurement range decreases when the length of PPLN increases. These results provide another way to fabricate well-working optical voltage sensor..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 932 (2004)
Optimum Parameters for Focusing of Optical Beams in Three-Dimensional Self-Defocusing Nonlinear Media
Li Huagang, and Guo Qi
A discussion is given about the focusing of optical beams due to the cross-phase modulation in three-dimensional self-defocusing nonlinear media. The effect on the focusing of the probe beams for the three initial parameters is discussed: the amplitude of the pump beam, the separation between the pump and the probe beaA discussion is given about the focusing of optical beams due to the cross-phase modulation in three-dimensional self-defocusing nonlinear media. The effect on the focusing of the probe beams for the three initial parameters is discussed: the amplitude of the pump beam, the separation between the pump and the probe beam centers and the wavelength ratio of the pump and the probe beams. The coupled amplitude equations are optimized based on the fact that the probe beam is much less intense than the pump beam, and cut the time of operating the programs much too. Our numerical results show that, the greater the amplitude of the pump beam and the wavelength ratio of the pump to signal beam are the better the probe focuses; the initial separation between the pump and the probe beams has an optimum values. The results can be used to design experiments in order to obtain the best effect of the focusing..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 937 (2004)
Effect of Microcosmic Optical Parameters of Doubly Doped LiNbO3 on Diffraction Efficiency
Ren Liyong, Liu Liren, and Liu Dean
By jointly solving the two-center material equations and the coupled-wave equations, a dynamic model to study the nonvolatile hologram realized by the two-color recording scheme (UV-light for sensitizing and He-Ne laser for recording) in doubly doped LiNbO3 crystals is set up. The aim is to study the effects of the micBy jointly solving the two-center material equations and the coupled-wave equations, a dynamic model to study the nonvolatile hologram realized by the two-color recording scheme (UV-light for sensitizing and He-Ne laser for recording) in doubly doped LiNbO3 crystals is set up. The aim is to study the effects of the microscopic optical parameters of the deep and shallow doping centers on the saturation and fixed diffraction efficiencies. These parameters include the photo-excitation coefficients of deep and shallow centers for sensitizing-light, the photo-excitation coefficient of shallow center for recording light, and the electron recombination coefficients of deep and shallow centers. Numerical solutions show that, for the nonvolatile holographic storage in doubly doped LiNbO3 crystals, in order to obtain high fixed diffraction efficiency, one should select the shallow center with large electron recombination coefficient, with high photo-excitation coefficient for recording light and with low photo-excitation coefficient for sensitizing-light; and select the deep center with high photo-excitation coefficient for sensitizing-light and with optimal electron recombination coefficient..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 941 (2004)
Photorefractive Holographic Storage Properties in Ce∶Fe-Doped LiNbO3 Crystals
Xu Xinguang, Xu Guibao, Hu Dawei, Wang Zhengping, Yang Xudong, Shao Zongshu, Xu Wusheng, and Xu Yuheng
Photorefractive holographic storage and optical transmission spectra properties were studied in a series of Ce∶Fe-doped LiNbO3 crystals including different dopants, different concentrations of dopants, and different post-proposed samples (as-grown or reduced or oxidized). The experimental results show that the top-qualPhotorefractive holographic storage and optical transmission spectra properties were studied in a series of Ce∶Fe-doped LiNbO3 crystals including different dopants, different concentrations of dopants, and different post-proposed samples (as-grown or reduced or oxidized). The experimental results show that the top-quality photorefractive holographic storage, the wide range of optical transmission spectra and the relatively small gain of two-wave coupling can be found in Ce-doped LiNbO3 crystal. The optical transmission spectra range and the gain of two-wave mixing is small in the high concentrations Fe-doped LiNbO3 crystals. Post-disposed (reduced or oxidized) samples had influence on the photorefractive property. The high gain of photorefractive two-wave coupling can be found in Ce∶Fe-doped reduced LiNbO3 crystal. The wider optical transmission spectra range can be obtained in the oxidized samples. And the greater gain of photorefractive two-wave coupling can be obtained in reduced samples. It is difficult to obtain the high gain of photorefractive two-wave coupling and the image storage quality simultaneously..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 947 (2004)
Identification of Chaotic Optical System Based on Support Vector Machine
Ye Meiying, and Wang Xiaodong
A support vector machine-based approach is presented for the identification of chaotic optical systems. The feasibility of this approach was demonstrated with the computer simulation through identifying a Bragg acoustooptic bistable chaotic system using a least squares support vector machine (LS-SVM). The proposed idenA support vector machine-based approach is presented for the identification of chaotic optical systems. The feasibility of this approach was demonstrated with the computer simulation through identifying a Bragg acoustooptic bistable chaotic system using a least squares support vector machine (LS-SVM). The proposed identification method was compared with the feed-forward neural network trained using back-propagation algorithm for the system identification. The LS-SVM possesses prominent advantages: over fitting is unlikely to occur by employing structural risk minimization criterion, the global optimal solution can be uniquely obtained owing to that its training is performed through the solution of a set of linear equations. Also, the LS-SVM needs not determine its topology in advance, which can be automatically obtained when training process ends. Thus its identifying accuracy and speed were found to be better than that of a conventional feed-forward neural network trained using back-propagation algorithm. This method is robust with respect to noise, and it constitutes another powerful tool for the identification of chaotic optical systems..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 953 (2004)
Optical Design and Fabrication
Design of the Primary Structure of the Birefringent Lens with the Concept of Pseudo-Chromatic Aberration and the PW Method
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The dual-focus interference microscope is applied in various areas because of its characteristics of high stability and resolution. The birefringent lens, consisting of a piece of birefringent crystal and a piece of optical glass, is a key component in the dual-focus interference microscope. In order to design the bireThe dual-focus interference microscope is applied in various areas because of its characteristics of high stability and resolution. The birefringent lens, consisting of a piece of birefringent crystal and a piece of optical glass, is a key component in the dual-focus interference microscope. In order to design the birefringent lens easily and promptly, not only the concept of “pseudo-chromatic aberration” introduced but also “the reciprocal of pseudo-chromatic dispersion” is defined. Thereby, with the use of the primary aberration theory and the PW method, a useful table of the primary structure of the birefringent lens is given, with the couple of three kinds of birefringent crystals and optical glasses, according to different demands; the calculation of aberration and optimum design are carried out by OSLO, an optical software, and the desired result is obtained. For the sake of evaluating the specific structure, the compact factor γ is defined as a criteria. As a concrete example, calcite and ZF1 are used as materials, the compact factor γ is 0.25..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 965 (2004)
Physical Optics
Optical Performance of Extreme-Ultraviolet Lithography for 50 nm Generation
Li Yanqiu
Extreme-ultraviolet lithography (EUVL) is one of the promising technologies for the fabrication of critical dimension of 100～32 nm. The optical performance of projection optics is most important to realize the fabrication of high resolution pattern. The design of 6-mirror projection optics of extremes-ultraviolet lithoExtreme-ultraviolet lithography (EUVL) is one of the promising technologies for the fabrication of critical dimension of 100～32 nm. The optical performance of projection optics is most important to realize the fabrication of high resolution pattern. The design of 6-mirror projection optics of extremes-ultraviolet lithography is presented and the optical performance is analyted by using optical design softwave CODE V. The resolution can reach 50 nm and the exposure area is 26 mm×1 mm. The performance of optics depends on the field points of the exposure area. The optical evaluation of optics is completed at full exposure area. The maximum distortion of 3.77 nm and the maximum wavefront error of 0.031λ (root-mean-square) can be reached. This projection optics can fully meet the requirements of EUVL for next generation..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 865 (2004)
The Developing Threshold Method for Precise Profile Control of Microlens Array with High Numerical Aperture
Dong Xiaochun, and Du Chunlei
A new method for precisely control of microlens profile is presented. First, the exposure dose distribution on the surface of photoresist is designed. According to the developing threshold characteristics of the photoresist, precise lens profile is obtained when the developing velocity reaches zero. The influence of deA new method for precisely control of microlens profile is presented. First, the exposure dose distribution on the surface of photoresist is designed. According to the developing threshold characteristics of the photoresist, precise lens profile is obtained when the developing velocity reaches zero. The influence of developing characteristics of graphic materials to microlens is decreased in this procedure. At last, microlens array with rise with of 114 μm is fabricated in the experiment. By using of this method, the manufacturing of micro-optical elements with high numerical aperture, deep relief depth and aspherical profile is possible..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 869 (2004)
Quantum Optics
Entropy Squeezing for a Two-Level Atom in Motion Interacting with a Quantized Field
Liao Xiangping, and Fang Maofa
The entropy squeezing of a two-level atom in motion interacting with a quantized field is investigated using quantum information entropy. The influences of the atomic motion and the field-mode structure on the atomic entropy squeezing are discussed. The numerical results obtained from the uncertainty relation of quantuThe entropy squeezing of a two-level atom in motion interacting with a quantized field is investigated using quantum information entropy. The influences of the atomic motion and the field-mode structure on the atomic entropy squeezing are discussed. The numerical results obtained from the uncertainty relation of quantum information entropy are compared to those obtained from the uncertainty relation of Heisenberg. It is shown that the atomic motion leads to the periodic evolution of the entropy squeezing; an increase in field-mode structure parameter results in not only shortening of the evolution period of the entropy squeezing but also prolonging of the squeezing time; the moving atom may exhibit long time entropy squeezing effect for some choisen system parameters; the definition of variance squeezing based on the uncertainty relation of Heisenberg is trivial when atomic inversion is zero and the information entropy squeezing is a high sensitive measure for the squeezing effect of the atom..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 983 (2004)
A Proposal for the Measurement of Quadrupole Field of Magneto-Optical Trap with Nonlinear Magneto-Optical Rotation
He Lingxiang, and Wang Yuzhu
In order to make sure the magnetic field distribution around the magneto-optical trap cold atoms, the weak variation and distribution around the zero-point magnet field can be analyzed. A theoretical analysis is based on the interaction between cold atoms and right-hand circular probe beams. For different transition prIn order to make sure the magnetic field distribution around the magneto-optical trap cold atoms, the weak variation and distribution around the zero-point magnet field can be analyzed. A theoretical analysis is based on the interaction between cold atoms and right-hand circular probe beams. For different transition probability of left and right-hand circularly polarized probe beam before and after zero-point magnetic field, nonlinear magnetic optical rotation (NMOR) induced by cold atoms is computed around the zero-point of 87Rb magneto-optical trap. Using such NMOR effects, rotation angle variation with the magnetic field can be got, even up to an order of magnitude 10-13 T. In the mean time, with such effect a two-peak-dispersionlike structure is developed, which is different from the results mentioned in other papers..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 989 (2004)
The Tavis-Cummings Model Entropy Property in a Phase Damping Cavity
Zhang Lihui, Gan Zhongwei, and Li Gaoxiang
The time evolution of the linear entropies for the atom-field coupling system, the atom and the field in Tavis-Cummings model in the presence of phase damping of field is investigated. The effects of the initial field states, different value of decay constant and the initial atomic states on all the entropies are discuThe time evolution of the linear entropies for the atom-field coupling system, the atom and the field in Tavis-Cummings model in the presence of phase damping of field is investigated. The effects of the initial field states, different value of decay constant and the initial atomic states on all the entropies are discussed.The results show that the different properties of the initial field prepared in the cavity can change the characters of all the linear entropies significatly.The evolution of the linear entropy of the system is independent of initial atomic preparation,but the linear entropy of the atom depends on the initial atomic state and independent of the cavity phase damping..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 993 (2004)
Spectroscopy
Neural Network Analysis and Application of Nonlinear Fluorescence Spectra
Shen Jinyuan, Han Yingzhe, Chang Shengjiang, Zhang Yanxin, Luo Qi, and Chin S L
Nonlinear fluorescence with distinguishable molecular spectra is emitted when fs laser pulses are launched in air due to the nonlinear effects between fs laser pulse and gases. Since every molecule has its particular feature in the fluorescence spectra, these fluorescence spectra can be used to analyze the components oNonlinear fluorescence with distinguishable molecular spectra is emitted when fs laser pulses are launched in air due to the nonlinear effects between fs laser pulse and gases. Since every molecule has its particular feature in the fluorescence spectra, these fluorescence spectra can be used to analyze the components of gases in the air. However, since the spectra created by different molecule overlap, it is hard to analyze the nonlinear spectra by the conventional spectroscopic analysis methods. A cascaded neural network model is proposed to analyze the nonlinear fluorescence spectra. To improve learning speed of the neural network and the recognition rate, some preprocessing has been done. 100% correct recognition rates are achieved for both training spectrum samples and test spectrum samples. The simulations show that the proposed algorithm is a new effective method for real-time recognizing the gas components without analytical sampling..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 1000 (2004)
Thin Films
Compression Effect of Angular Width for Polarization Beam Splitter Under Tilted Incidence
Xu Xueke, Tang Zhaosheng, Fan Zhengxiu, and Shao Jianda
Compression effect of angular width for polarizing beam splitter under tilted incidence is caclulated. The calculated result shows that the larger the tilted angle is, the more distinct the compression effect, difference of substrate refractive index has little influence on the compression effect. The conclusion is tesCompression effect of angular width for polarizing beam splitter under tilted incidence is caclulated. The calculated result shows that the larger the tilted angle is, the more distinct the compression effect, difference of substrate refractive index has little influence on the compression effect. The conclusion is testfied by the designing of thin fim coatings ulteriorly. In practical use when the direction of incident light is kept invariable the compression effect of angular acceptance width can be realized by changing the shape of the PBS prism. The result has a great help to design polarizing beam splitter with a wide augluar acceptance and spectrum bandwidth in practice..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 881 (2004)
A New Method for Determination of the Optical Constants and Thickness of Thin Film
Shen Weidong, Liu Xu, Ye Hui, and Gu Peifu
Based on the dispersion equations，“Downhill Simplex” method is utilized to measure the thickness and optical constants of thin film by fitting the curve of measured transmission spectrum. TiO2, Si3N4 thin films deposited by electron gun evaporation and reactive magnetron sputtering respectively are measured with CauthyBased on the dispersion equations，“Downhill Simplex” method is utilized to measure the thickness and optical constants of thin film by fitting the curve of measured transmission spectrum. TiO2, Si3N4 thin films deposited by electron gun evaporation and reactive magnetron sputtering respectively are measured with Cauthy formula and ITO film deposited by electron gun evaporation with Drude formula. Experiments show that the results got by this method and by α-step apparatus agree well. No initial input is necessary for this simple method to realize the global optimization. With various dispersion formula, it is also suitable for many kinds of films with thinner thickness, which will be useful in thin film optics, microelectronic and micro-optical electro-mechanical system (MOEMS)..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 885 (2004)
Structure Analysis and Optical Properties of Heat-Induced Crystalline High Reflection SbOx Films
Fang Ming, Li Qinghui, and Gan Fuxi
SbOx thin films were prepared by the method of reactive dc magnetron sputtering; the optical properties and structural changes of the films were studied by using X-ray diffraction analysis and spectrometer respectively. By using the differential scanning calorimeter data of the amorphous film powder, measuring the peakSbOx thin films were prepared by the method of reactive dc magnetron sputtering; the optical properties and structural changes of the films were studied by using X-ray diffraction analysis and spectrometer respectively. By using the differential scanning calorimeter data of the amorphous film powder, measuring the peak temperature of crystallization at different heating rates, the crystallization kinetics of the thin films were studied.The results indicated that the as-deposited films were amorphous and there were two stages during the heat-induced crystallization. The first stage was the nanocrystallization of a primary phase antimony; the second stage was related to the formation of cubic Sb2O3 phase at higher temperatures. The Sb and Sb2O3 existed in crystalline films after annealed and there were much more Sb2O3 in 300 ℃ annealed films. The reflectivity of crystalline films was higher than that of the as-deposited films. The reflectivity of 200 ℃ annealed film was the highest in all crystalline films..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 890 (2004)
X-Ray Optics
Influence of Incident Energy on Reconstructed Atomic Images in X-Ray Fluorescence Holography
Xie Honglan, Chen Jianwen, Gao Hongyi, Xiong Shisheng, Li Ruxin, and Xu Zhizhan
X-ray fluorescence holography is a novel microscopic imaging method, which can provide the information of three-dimensional atomic arrangement in a single crystal. However, obvious twin images apperar on the cetomic images dotained by this method. Therefore, the method called “multiple-energy X-ray hologrophy” that imaX-ray fluorescence holography is a novel microscopic imaging method, which can provide the information of three-dimensional atomic arrangement in a single crystal. However, obvious twin images apperar on the cetomic images dotained by this method. Therefore, the method called “multiple-energy X-ray hologrophy” that images reconstructed from holograms recorded at several incident energies are combined properly is used to remove the twin images. In this work, a single Fe atom and multi Fe atoms as model respectively, holograms recorded in a complete 4π solid angle with different range and magnitude of incident energies are calculated. Compared reconstructed atomic images from these holograms, it is found that the wider range of incident energies, the better effect of removing twin images is. Moreover, the difference between simulated peak positions and actual atomic positions decreases and the resolution of reconstructed atomic images increases with increasing incident energy..
Acta Optica Sinica
- Publication Date: Aug. 15, 2021
- Vol. 24, Issue 7, 1004 (2004)
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