Contents
2008
Volume: 28 Issue 2
36 Article(s)
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Atmospheric Optics and Oceanic Optics
Experimental Demonstration of Stochastic Parallel Gradient Descent Control Algorithm for Adaptive Optics System
Yang Huizhen, Chen Bo, Li Xinyang, and Jiang Wenhan
The stochastic parallel gradient descent algorithm (SPGD) is a promising control algorithm for adaptive-optics (AO) system, which is independent of wave-front sensor and can optimize the system performance directly. Based on SPGD, an adaptive-optics test-bed was built with a 32-element deformable mirror and a CCD. The The stochastic parallel gradient descent algorithm (SPGD) is a promising control algorithm for adaptive-optics (AO) system, which is independent of wave-front sensor and can optimize the system performance directly. Based on SPGD, an adaptive-optics test-bed was built with a 32-element deformable mirror and a CCD. The principle of SPGD control algorithm was demonstrated through examining the effects of gain and perturbation amplitude on correction capability and convergence rate. Experimental results show SPGD can correct static distorted wave-front successfully when the gain and the perturbation amplitude were appropriate for distorted wave-front. The main effects on correction speed were discussed through analyzing experimental results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 205 (2008)
Atomic and Molecular Physics
A Novel Controllable Four-Well Optical Trap for Cold Atoms or Molecules and Its Two-Dimensional Optical Lattices
Lu Junfa, Ji Xianming, Zhou Qi, and Yin Jianping
Atomic optical lattices offer a method for manipulating neutral atoms accurately and study on several basic problems in physics. We propose a novel scheme to form a controllable four-well optical trap for cold atoms or molecules by using an optical system composed of an amplitude cosine grating and a lens illuminated bAtomic optical lattices offer a method for manipulating neutral atoms accurately and study on several basic problems in physics. We propose a novel scheme to form a controllable four-well optical trap for cold atoms or molecules by using an optical system composed of an amplitude cosine grating and a lens illuminated by a plane light wave. We calculate the intensity distribution of the four-well optical trap, discuss the evolution process of the optical trap from four wells to double wells or single well, and derive the analytical relations between the characteristic parameters of the four-well trap (including geometric parameters, intensity distribution, intensity gradients and their curvatures) and the parameters of the optical lens system. The study shows that this four-well trap can continuously evolve into a double-well or single-well one by changing space frequency of the cosine grating, and the dependence of the distance between the trapping centers of the four wells or two ones on the grating space frequency is obtained..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 211 (2008)
Fiber Optics and Optical Communications
Dual-Peak Resonance and Transmission Spectrum in Coated Long-Period Fiber Grating
Gu Zhengtian, Xu Yanping, and Deng Chuanlu
By resolving the characteristic equation of coated long-period fiber grating (LPFG), the dual peak resonant wavelengths is determined based on rigorous coupled-mode theory. The relationship between the dual-peak resonant wavelengths and grating period, the mode order is studied. The results show that the dual resonanceBy resolving the characteristic equation of coated long-period fiber grating (LPFG), the dual peak resonant wavelengths is determined based on rigorous coupled-mode theory. The relationship between the dual-peak resonant wavelengths and grating period, the mode order is studied. The results show that the dual resonance appears in higher cladding mode. The higher the cladding mode order is, the smaller the related grating period required to couple with core mode is. Furthermore, the influence of film optical parameters and grating structure parameters on the intervals of dual-peak resonant wavelengths, as well as the attenuation peak of transmission spectra, are analyzed. The results are coincident with the non-coated long-period fiber grating experiment made by X. W. Shu. The research provides theoretical foundation for the structural optimization of dual-peak resonance film sensors with high sensitivity..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 219 (2008)
Analysis of Polarization Mode Dispersion Compensation Performance for Different Modulation Formats
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The generation of different modulation formats and their polarization dispersion compensation (PMD) performance have been studied. Firstly, the eye diagrams and spectrum of different modulation formats through experiment have been obtained, and then the dynamic combination of their mitigation and compensation in PMD haThe generation of different modulation formats and their polarization dispersion compensation (PMD) performance have been studied. Firstly, the eye diagrams and spectrum of different modulation formats through experiment have been obtained, and then the dynamic combination of their mitigation and compensation in PMD have been accomplished. Secondly, the PMD compensation performance with degree of bolarization (DOP) as feedback signal of the mentioned modulation formats has been studied via simulation. It shows that DOP responsibility and PMD compensation performance of differential phase-shift key (DPSK) are better than that of on-off keying (OOK). CSRZDPSK combines the carrier-suppressed characteristic of CSRZ formats and specific spectrum characteristic of DPSK formats, therefore it has the best PMD compensation performance..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 226 (2008)
The Moving Characteristics of Directional Driving Motor in Space Tracking System
Zhang Honglei, Yang Yan, Hu Shanjiang, Zang Huaguo, Chen Weibiao, and Lu Yutian
An experimental device of laser scanning, acquisition and tracking in deep-space non-cooperative target was designed, and the courses of scanning and tracking between two satellites at the same orbit were simulated, the smallest acceleration of laser directional driving motor in the scanning and tracking device and itsAn experimental device of laser scanning, acquisition and tracking in deep-space non-cooperative target was designed, and the courses of scanning and tracking between two satellites at the same orbit were simulated, the smallest acceleration of laser directional driving motor in the scanning and tracking device and its moving characteristics during scanning and tracking were calculated theoretically. Theoretical analysis and simulation shows that the direction driving motor accelerates first, and then decelerates to compensate for the eccentricity when the satellite is deviated from laser center with a certain distance, and reacquires the tracking satellite. The needed time from reacquisition to tracking is affected by motor acceleration, telescope′s detecting precision, and detector′s response and treatment time, and the effect of detector precision on the reacquisition and re-tracking time is greater, as a result, the detector response and treatment time is decreased to the least. In order to make the satellite within the scope of scanning laser spot during acquisition and tracking, the smallest angular acceleration of the driving motor of the theodolite is 25.5°/s2..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 233 (2008)
A Novel Scheme for Optical Millimeter-Wave Generation Based on Double-Sideband Modulation
Hu Liliang, Chen Lin, Yu Jianjun, and Wen Shuangchun
A novel scheme for optical millimeter-wave generation with double-sideband (DSB) modulation by external modulator in a radio-over-fiber (ROF) system was proposed. At the central station, a CW lightwave was intensity-modulated by the RF signal to generate DSB signal. After the pure optical carrier was filtered, an opticA novel scheme for optical millimeter-wave generation with double-sideband (DSB) modulation by external modulator in a radio-over-fiber (ROF) system was proposed. At the central station, a CW lightwave was intensity-modulated by the RF signal to generate DSB signal. After the pure optical carrier was filtered, an optical interleaver was employed to separate the spectrum of the upper sideband and the lower sideband of the generated DSB signal. After the lower sideband signal was modulated with a baseband data at 2.5 Gbit/s, it was recombined with the unmodulated signal to generate optical millimeter wave, and then transmitted to the base station over single-mode fiber (SMF). In the base station, the electrical millimeter wave signal was generated by O/E conversion. The dispersion performance of the generated mm-wave is theoretically analysed, it can immune the fading effect. The experimental results show that the downlink data signals can transmit over 50 km fiber without dispersion compensation, and the power penalty is less than 1 dBm. So the generated optical millimeter wave by proposed method can effectively reduce baseband signal degeneration caused by the time shift of the code edges because of fiber dispersion, it is suitable for long distance transmission..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 238 (2008)
Research on the Stress Zones and Birefringence of Circular-Core Side-Hole Fiber
Wei Yan, Chang Deyuan, Zheng Kai, and Jian Shuisheng
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 243 (2008)
Noninverted Wavelength Conversion for 40 Gb/s Return-to-Zero Signal Based on Semiconductor Optical Amplifier and Optical Bandpass Filter
Zhang Aixu, Yu Jinlong, Wang Yaotian, Chui Yue, Hu Hao, and Yang Enze
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 249 (2008)
Photonic Crystal Fiber Based Fabry-Pérot Sensor Fabricated by Using 157 nm Laser Micromachining
Deng Hongyou, Rao Yunjiang, Ran Zengling, Liao Xian, and Liu Weijun
A micro rectangle hole is ablated in a photonic crystal fiber by using 157 nm excimer laser pulses to form a fiber Fabry-Pérot cavity (PCF F-P), because the 157 nm excimer laser used in micromachining has high single-photon energy, high peak power, high absorption coefficient and high resolution. The PCF F-P cavitA micro rectangle hole is ablated in a photonic crystal fiber by using 157 nm excimer laser pulses to form a fiber Fabry-Pérot cavity (PCF F-P), because the 157 nm excimer laser used in micromachining has high single-photon energy, high peak power, high absorption coefficient and high resolution. The PCF F-P cavity with a length of ～45.6 μm has obtained a smooth interference fringe and an excellent fringe visibility of ～26 dB. An explanation for the formation of such a high quality cavity is presented based on the interaction mechanism between the laser and silica material. This PCF F-P is used for measurement of strain and a sensitivity of 0.32 nm/μm and a linearity of 0.9994 within a range of 550 μm are obtained. Furthermore, it is verified that the PCF F-P sensor is insensitive to temperature change as the cavity length only changes 20 nm for a temperature range of 800 ℃. Such a fiber Fabry-Pérot cavity is fabricated easily and formed straightforwardly with high efficiency and precision, leading to the possibility of mass production of high-quality PCF F-P cavities then extensive applications..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 255 (2008)
Instrumentation, Measurement and Metrology
A New Fast Phase Unwrapping Method
Gai Shaoyan, and Da Feipeng
A new fast and robust phase-codeing-unwrapping algorithm is proposed. By alternating the center area of fringes, the code information is added to the phase-shifting fringes, which include not only the primary phase information but also the code information for phase unwrapping. An alteration function is constructed to A new fast and robust phase-codeing-unwrapping algorithm is proposed. By alternating the center area of fringes, the code information is added to the phase-shifting fringes, which include not only the primary phase information but also the code information for phase unwrapping. An alteration function is constructed to catch the code information and then give the unwrapped phase. The error and noise of the alteration function is discussed, then a new filter method called directional filtering is proposed to remove the noise, and the mistakes of phase unwrapping are depressed by this method. The simulation and experimental results show the feasibility of the new algorithm. The speed and dependability of the new algorithm are much better than those of the traditional method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 259 (2008)
Experimental Investigation on Surface/Subsurface Damage of Nd-Doped Phosphate Glass
Zhang Wei, and Zhu Jianqiang
This paper investigated the influence of abrasive size, load and spindle speed in grinding process on surface/subsurface damage of Nd-doped phosphate glass experimentally. Results show that the surface roughness is affected little by spindle speed and load. Subsurface damage is much greater in low spindle speed or heavThis paper investigated the influence of abrasive size, load and spindle speed in grinding process on surface/subsurface damage of Nd-doped phosphate glass experimentally. Results show that the surface roughness is affected little by spindle speed and load. Subsurface damage is much greater in low spindle speed or heavier load. Both surface roughness and subsurface damage are linear to the maximum nominal abrasive size. When the load is doubled, the ratio of subsurface damage to surface roughness increases by 0.05. All the investigating results provide essential foundation for optimizing fabrication techniques of Nd-doped phosphate glass..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 268 (2008)
Photoelastic Phase-Shifting Technique
Ji Xinhua, Zhang Lina, Shi Lijun, Chen Jinlong, and Qin Yuwen
Taking the disk under diametral compression as an example, the whole-field isoclinic-angle phase of the model was analyzed according to elastic mechanics, and the principal-stress direction was put forward. Base on six-step phase shifting technique, the actual phase of whole-field isoclinic angle and whole-field isochrTaking the disk under diametral compression as an example, the whole-field isoclinic-angle phase of the model was analyzed according to elastic mechanics, and the principal-stress direction was put forward. Base on six-step phase shifting technique, the actual phase of whole-field isoclinic angle and whole-field isochromatic of a disk was extracted. Combining finite element software MARC with fitting of shape function, six-step phase shifting and isochromatic phase patterns of a ring under diametral compression were simulated. This method can be generalized to simulate the photoelastic experiment of stress model with complex analytic solution or without analytic solution. The feasibility of this method was proved by the experiments of a disk under diametral compression, and the information of whole-field isochromatic could be extracted automatically..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 273 (2008)
Analysis of Affecting Factors on Surface Roughness Measurement Based on Polychromatic Speckle Elongation
[in Chinese], and [in Chinese]
Speckle elongation phenomenon can be observed when rough surface is illuminated by a polychromatic laser beam. Based on this dependence the surface roughness can be determined, in which the influence of transverse characteristic of rough surface can be neglected when certain conditions are satisfied. Through numerical Speckle elongation phenomenon can be observed when rough surface is illuminated by a polychromatic laser beam. Based on this dependence the surface roughness can be determined, in which the influence of transverse characteristic of rough surface can be neglected when certain conditions are satisfied. Through numerical simulation of polychromatic speckle pattern of random rough surface, by application of the local autocorrelation function of polychromatic speckle pattern using spatial average, the dependence of average speckle elongation ratio 〈χ〉 on root-mean-square σh of surface profile amplitude is studied, and the influences of experimental factors are investigated, such as the wavelength combination of laser beams, the cell size and the resolution depth of image acquisition device on measure result. The results show that describing the polychromatic speckle elongation effect by autocorrelation function using spatial average instead of ensemble average is effective, and to obtain enough precision of surface roughness measurement, appropriate wavelength combination of laser beams and appropriate cell size of image acquisition device should be chosen..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 279 (2008)
Integrated Optics
Optimized Design for Tunable Optical Waveguide Ring Resonator Integrated with Thermo-Optic Mach-Zehnder Interferometer
Zhang Xiaoyang, Zhang Tong, Ji Chunling, Chu Feng, Wang Tong, and Cui Yiping
The transmission characteristics of optical waveguide ring resonator with tunable Mach-Zehnder interferometer (MZI) are analyzed. The formulas of the intensity and phase transfer functions are deduced according to the coupled-mode theory. It shows that the resonant frequencies shift range and the modulation power of MaThe transmission characteristics of optical waveguide ring resonator with tunable Mach-Zehnder interferometer (MZI) are analyzed. The formulas of the intensity and phase transfer functions are deduced according to the coupled-mode theory. It shows that the resonant frequencies shift range and the modulation power of Mach-Zehnder interferometer are heavily dependent on the parameters of Mach-Zehnder interferometer. An optimized design for ring resonator is demonstrated, the numerical ring modeling with the radius of 2 cm and the propagation loss of 0.08 dB/cm is performed around the central wavelength of 1550 nm, the resonant frequencies shift range is lower than 0.027 GHz, and the maximum notch depth is obtained, it means that the frequency modulator with small bandwidth can be used for the ring resonator and the finesse can be tuned with lower power..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 285 (2008)
Lasers and Laser Optics
Study of Polarized Bidirectional Reflectance Distribution Function Model for Painted Surfaces
Feng Weiwei, Wei Qingnong, Wang Shimei, Wu Yunzhi, Liu Shisheng, Wu Dexia, Liu Zengdong, and Wang Dongfang
In order to represent optical scattering properties of the complex painted surfaces, based on microfacet theory for polarized bidirectional reflectance distribution function (BRDF), genetic algorithm is used to get the key parameters in the model. Numerical simulation is done using C++ language and the impact of the moIn order to represent optical scattering properties of the complex painted surfaces, based on microfacet theory for polarized bidirectional reflectance distribution function (BRDF), genetic algorithm is used to get the key parameters in the model. Numerical simulation is done using C++ language and the impact of the model parameters is analyzed. The comparison between numerical simulation results and experimental data indicate: this model has the higher precision for simulation, and can be used as a reference for target feature extraction and recognition in the future..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 290 (2008)
Investigation of Conversion Efficiency of Widely Tunable Continuous-Wave Mid-IR Difference Frequency Generation Fiber-type Laser
Jiang Jian, Li Xiaoqin, Feng Sujuan, Wang Zhishan, Mao Qinghe, and Liu Wenqing
The conversion efficiency properties of a widely tunable continuous wave Mid-IR fiber-type laser source based on difference frequency generation (DFG) process in a periodically poled MgO-doped LiNbO3 (PPMgLN) crystal, which uses a ytterbium-doped fiber laser (YDFL) as the pump and an erbium-doped fiber laser (EDFL) casThe conversion efficiency properties of a widely tunable continuous wave Mid-IR fiber-type laser source based on difference frequency generation (DFG) process in a periodically poled MgO-doped LiNbO3 (PPMgLN) crystal, which uses a ytterbium-doped fiber laser (YDFL) as the pump and an erbium-doped fiber laser (EDFL) cascaded by an erbium-doped fiber amplifier (EDFA) as the signal respectively, are investigated in this paper. Our results show that, the polarization states of pump and signal beams influence the conversion efficiency of the DFG process. By using polarization controllers (PCs), the polarization orientations of pump and signal beams may be respectively adjusted to be parallel to the principle optical axis of the crystal for obtaining high conversion efficiency. The beam quality of the pump and the signal not only influence on the conversion efficiency of the DFG process, but also determine the tolerance of the crystal position along the beams. For a focusing system formed by a fiber grin lens and a convex-plane lens with the focal length of 100mm, the conversion efficiency and the tolerance for the DFG source are 0.717 mW-2 and 44 mm, respectively. Moreover, the conversion efficiency of the DFG process changes very small when the idle light is tuned in the wavelength range between 3126.36 nm and 3529.6 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 295 (2008)
Choice of Operating Point for the Four-Mode Differential Laser Gyros
Wang Zhiguo, Long Xingwu, Wang Fei, Tan Zhongqi, and Xu Guangming
The four-mode differential laser gyros (FMDLGs) would have better performance when operating at the point with equal scale factors for left circularly polarized (LCP) and right circularly polarized (RCP) gyros. In order to find the optimal operating point, expressions for FMDLG beat frequency are analyzed. Theoretical The four-mode differential laser gyros (FMDLGs) would have better performance when operating at the point with equal scale factors for left circularly polarized (LCP) and right circularly polarized (RCP) gyros. In order to find the optimal operating point, expressions for FMDLG beat frequency are analyzed. Theoretical study shows that the sum frequency as a function of piezoelectric transducer (PZT) scanning voltage is quadratic and the scale factors of the LCP and RCP gyros are equal when the quadratic function is at its turning point. Therefore, theoretical optimal operating point can be obtained by recording beat frequency of the FMDLG while scanning the PZT voltage. And actual optimal operating point can be obtained by testing the FMDLG at different operating point. Experimental results give an approximate coincidence of theoretical and actual optimal operating point with maximum error of 2 Hz, which shows a reference method to choose optimal operating point for FMDLGs..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 301 (2008)
Materials
Spectral Properties of Tm3+-Doped SiO2-Al2O3-PbF2-AlF3 Glasses
Lin Qiongfei, Xia Haiping, Wang Jinhao, Zhang Yuepin, Yang Gangfeng, and Zhang Qinyuan
Glasses with the compositions of 0.3SiO2-0.1Al2O3-0.1AlF3-0.5PbF2 doped with different Tm3+ concentration (x=0.5 mol%,1.0 mol%,2.0 mol%,3.0 mol%) were fabricated by conventional melting method. According to the absorption spectra and the Judd-Ofelt theory, the J-O strength parameters (Ω2,Ω4,Ω6) of Tm3+ were calculated,Glasses with the compositions of 0.3SiO2-0.1Al2O3-0.1AlF3-0.5PbF2 doped with different Tm3+ concentration (x=0.5 mol%,1.0 mol%,2.0 mol%,3.0 mol%) were fabricated by conventional melting method. According to the absorption spectra and the Judd-Ofelt theory, the J-O strength parameters (Ω2,Ω4,Ω6) of Tm3+ were calculated, by which the radiative transition probabilities, fluorescence branching ratios and radiative lifetimes were obtained. The infrared emission spectra (with 808 nm laser diode excitation) at ～1.47 μm and ～1.8μm of various concentration Tm3+-doped glasses were studied. The emission intensity at 1.8 μm reaches to the maximum when the Tm3+-doping concentration is near to be 2.0 mol% and then decreases at higher concentration. The mechanism of the change of the fluorescence intensity was explained from the cross-relaxation effect and the concentration quenching effect of Tm3+. The absorption cross section of 3H6→3F4 transition and the stimulated emission cross section of 3F4→3H6 transition of Tm3+ have also been calculated according to McCumber theory..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 305 (2008)
Accurate Measurement of Quantum Yields for Visible Emission Transitions of Sm3+
Wang Xueying, Li Changmin, Yu Xiaobo, Yang Dianlai, Lin Hai, and Setsuhisa Tanabe
Quantum yields for multichannel transition emissions have been determined in Sm3+-doped heavy metal tellurite glass under the pumping of blue lighting emitting diode. To achieve this intention, the necessary fluorescence spectra were measured and calibrated in an integrating sphere with 25.4 cm diameter, which was connQuantum yields for multichannel transition emissions have been determined in Sm3+-doped heavy metal tellurite glass under the pumping of blue lighting emitting diode. To achieve this intention, the necessary fluorescence spectra were measured and calibrated in an integrating sphere with 25.4 cm diameter, which was connected to a CCD detector. Standard halogen lamp was used for calibrating the measurement system and auxiliary halogen lamp was applied to determine the changes in throughput at the different steps of the measurement. The spectral power distribution of the sample under the blue light emitting diode (LED) pumping was derived from the measured spectra firstly, and then the quantum yields for the visible emissions of Sm3+ were calculated based on the distribution and the total quantum yields in visible region is 7.55%..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 311 (2008)
Making and Spectra Property of the Composite Yb:Y3Al5O12/Y3Al5O12 Crystal
Wang Jingya, Wang Xiaodan, Zhao Zhiwei, Xu Jun, Gilbert Bourdet, and J.-C. Chanteloup
The composite Yb:Y3Al5O12/ Y3Al5O12 crystal was made by thermal bonding method, twelve pieces of composite crystals were made by different technological parameter in manufacturing process. The bonding interface of the composite crystals were observed by optical microscope, transmission spectra of the composite crystalsThe composite Yb:Y3Al5O12/ Y3Al5O12 crystal was made by thermal bonding method, twelve pieces of composite crystals were made by different technological parameter in manufacturing process. The bonding interface of the composite crystals were observed by optical microscope, transmission spectra of the composite crystals were studied. We get appropriate making technology of the composite crystals from above result. Bonding quality of composite crystals were characterized by the shape of transmission spectra and transmittance of Yb:YAG/YAG composite crystals. All experiments show that the composite YbYAG/ YAG crystal has good bonding quality and integration is feusible..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 316 (2008)
Triplet Energy Transfer in Porphyrin-Based Molecular Assembled System
Zhang Kun, Wang Zhiqiang, Wang Fangfang, Zhu Baohua, Gu Yuzong, and Guo Lijun
The photophysical properties of porphyrin-based assembled molecular system was investigated using steady-state fluorescence and transient absorption. The obtained results indicate the existence of energy transfer process from the triplet state of donor ZnP to the acceptor Fe(Cl)P, mediated by the bridge molecule. At roThe photophysical properties of porphyrin-based assembled molecular system was investigated using steady-state fluorescence and transient absorption. The obtained results indicate the existence of energy transfer process from the triplet state of donor ZnP to the acceptor Fe(Cl)P, mediated by the bridge molecule. At room temperature, the fluorescence of ZnP was quenched dramatically with the presence of acceptor Fe(Cl)P, implying the energy transfer between donor and acceptor. By comparison of the triplet state lifetime of ZnP in reference and assembled system, it was observed the excitation energy of donor's triplet state is quenched by a factor of 5, and the rate constant for energy transfer is around 7.2×105 s-1. The temperature dependence of energy transfer rate constant indicates the influence of conformation on the electronic coupling between donor and acceptor mediating by the bridge molecule. Considering the spatial distance between donor and accepter being upto 2.5 nm, it could be concluded that superexchange mechanism via bridge dominates the deactivation of excited triplet state of ZnP in the assembled porphyrin dimer..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 321 (2008)
Medical Optics and Biotechnology
Rapid Detection of the Quality Indicators in Glycerol Monolaurate Products Using Fourier Transform Infrared Spectroscopy
Feng Fengqin, Zhang Hui, Wang Li, and He Yong
Glycerol monolaurate (GML) is a food additive which is widely used. The products prepared by esterification of glycerol and lauric acid followed by molecular distillation have lauric acid, glycerol and other impurities. To detect the glycerol monolaurate, lauric acid and glycerol in the products is a very tedious proceGlycerol monolaurate (GML) is a food additive which is widely used. The products prepared by esterification of glycerol and lauric acid followed by molecular distillation have lauric acid, glycerol and other impurities. To detect the glycerol monolaurate, lauric acid and glycerol in the products is a very tedious process using traditional methods such as chemical titrimetry and gas chromatography. For fast quality detection of the products that has been analyzed on gas chromatography, Fourier transform infrared spectroscopy (FTIS) was used in this study. Principal component analysis (PCA) and back-propagation artificial neural networks (BP-PANN) were used to build the regression model. Then this model was used to detect the glycerol monolaurate, lauric acid and glycerol of samples in the validation set according to their spectra. Root mean square error prediction (RMSEP) and correlation coefficient (r) of prediction were used as the evaluation standards, the predicted results of GML was PRMSE＝3.6376, r＝0.9950, the predicted results of glycerol was PRMSE＝1.4764, r＝0.9795 and the predicted results of lauric acid was PRMSE＝1.2859, r＝0.9247. The results indicated that it was feasible to detect glycerol monolaurate, lauric acid and glycerol content using spectroscopic technique..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 326 (2008)
Construction of Individual Eye Model Considering the Orientation of Visual Axis
Liu Ming, Wang Zhaoqi, Wang Yan, and Zhao Kanxing
Individual eye model capturing more anatomy properties and structural features of human eye has important experimental and clinical value. Based on corneal topographical maps, the angles between visual axis and optical axis of 8 human eyes are identified. The horizontal average value is 4.23°±1.51°, and Individual eye model capturing more anatomy properties and structural features of human eye has important experimental and clinical value. Based on corneal topographical maps, the angles between visual axis and optical axis of 8 human eyes are identified. The horizontal average value is 4.23°±1.51°, and the vertical average value is -0.40°±1.27°. With the angle, corneal topographical data, eye's axial lengths data and wavefront aberrations, individual eye models considering the orientation of visual axis for eight normal eyes are constructed with the optical design software Zemax. Based on the constructed individual eye model, wavefront-optimized ablation depth is calculated, and the result is compared with the depth calculated from optical path difference (OPD) method. At the center of optical zone, the difference of the two depths is slight, and the average value is (0.09±0.04) μm; the difference increases with the increase of radius. In our eight examples, the greatest difference in the periphery of the optical zone is 0.59 μm. Individual eye model provides a useful tool for calculating wavefront-optimiaed ablation profiles to precompensate for the wavefront aberrations of human eye..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 331 (2008)
Optical Design and Fabrication
Optimization of Topside Antireflective Coatings for Hyper Numerical Aperture Lithography
Zhou Yuan, and Li Yanqiu
In hyper numerical aperture (NA) lithography, the incident angle of imaging rays varies in a wide range. Conventional topside antireflective coatings (TARC) optimization methods, minimize the reflectivity only for normal incident light, but are insufficient to suppress the reflectivity in the whole incident angles rangIn hyper numerical aperture (NA) lithography, the incident angle of imaging rays varies in a wide range. Conventional topside antireflective coatings (TARC) optimization methods, minimize the reflectivity only for normal incident light, but are insufficient to suppress the reflectivity in the whole incident angles range of the incoming imaging rays for hyper-NA lithography. A novel TARC optimization method is developed, and the average reflectivity at the resist/TARC/air (or immersion fluid) interface is calculated over the whole range of incident angles that NA determines. Optimal design of TARC structure is carried out to minimize the reflectivity. The results show that, with this method, the thin-film interference effects which cause remarkable line width fluctuation can be reduced, the swing curve effect is controlled, the transmittance of TARC and the ratio of transmittance of TE to that of TM waves are increased, so that the scanner throughput and image contrast, can be improved..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 337 (2008)
High Performance Complex Optical System Design for Sun Sensor
Jiang Jie, Wen Zhiming, Zhang Guangjun, and Fan Qiaoyun
Based on the Fraunhofer diffraction theory and a microlens, a high-performance complex optical system for a digital sun sensor is designed . The structure of this optical system is analyzed and the mathematic model is established. The focus, aperture and microlens parameters of the optical system are given and the numeBased on the Fraunhofer diffraction theory and a microlens, a high-performance complex optical system for a digital sun sensor is designed . The structure of this optical system is analyzed and the mathematic model is established. The focus, aperture and microlens parameters of the optical system are given and the numeric simulation is carried out. The simulative results show that the energy distribution of the spot formed by the novel complex optical system is concentrated compared with a masking optical system, so the high calculational accuracy of facular centroid is guaranteed. Meanwhile, the sensor with the novel optical system possesses a large field of view and high accuracy..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 344 (2008)
Optical Devices
A Soft-Lithography-Based Vertically Coupling Structure for Multilayered Optical Interconnection
Liu Yanting, Ni Wei, and Wu Xingkun
A novel vertical coupling structure is designed for multilayered optical interconnection, regarding as one of most promising approaches for high-speed communications in next-generation computer. The layer-to-layer coupling features a simple S-shaped structure with an insertion loss as low as 0.05 dB. For four cross secA novel vertical coupling structure is designed for multilayered optical interconnection, regarding as one of most promising approaches for high-speed communications in next-generation computer. The layer-to-layer coupling features a simple S-shaped structure with an insertion loss as low as 0.05 dB. For four cross sections of 30 μm×30 μm, 50 μm×50 μm,100 μm×100 μm, and 200 μm×200 μm calculations for cross-over of up to 6 layers were performed using Monte Carlo ray tracing simulation, it was found that a low-loss coupling (less than 1 dB) can be achieved as the ratio of cross-over height to traveling distance is about 0.128. Experimental prototypes were fabricated by using soft-lithography and measurement agrees with the calculated result in general..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 349 (2008)
Frequency-Varying Fringes Projector Based on Acoustic Grating
Zhao Huijie, Zeng Junyu, and Lei Yanzhang
A new acoustic grating fringe projector (AGFP) was developed for solving the problems of the low speed, complex structure and hard on-line integration of the traditional structure light illuminator in three-dimensional (3-D) measurement. An acousto-optic deflector (AOD) driven by a beat frequency signal generated two oA new acoustic grating fringe projector (AGFP) was developed for solving the problems of the low speed, complex structure and hard on-line integration of the traditional structure light illuminator in three-dimensional (3-D) measurement. An acousto-optic deflector (AOD) driven by a beat frequency signal generated two overlap gratings inside the acousto-optic (AO) crystal and diffracted the incident laser beam into two first-order beams. The two first-order beams were brought together by a projection lens and the fringe pattern was generated by the interference of them. We established the math model of the fringe pattern and proposed a new method called ‘phase freezing’ to explain the changes of the spatial period and phase of fringes. The acousto-optic technique for producing fringe patterns provided a number of significant benefits, such as completely solid state, small scale, electronically control without any mechanical moving part, high precision and dynamic programmable ability. We obtained a precise phase map of a plaster statue with the device. The projection system is of great engineering value in high-accuracy three-dimensional non-contact complicated profile measurement..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 355 (2008)
Aspherical Liquid Micro-Lens Manipulated by Electrostatic Forces
Zhan Zhenxian, He Jianhui, Yao Haitao, and Wang Keyi
A novel method of fabricating zoom aspherical liquid micro-lens from ultra-violet (UV) curable polymer with on-line measurement is proposed. Electrostatic forces are employed to manipulate the shape of liquid polymer lens. Surface profile distortions of the liquid lens result in its focus variability. UV light is emploA novel method of fabricating zoom aspherical liquid micro-lens from ultra-violet (UV) curable polymer with on-line measurement is proposed. Electrostatic forces are employed to manipulate the shape of liquid polymer lens. Surface profile distortions of the liquid lens result in its focus variability. UV light is employed to cure the liquid lens when its surface profile and focal spot are appropriate. Therefore, aspherical micro-lens with nice optical imaging and focusing abilities can be fabricated. An experimental system which can fabricate zoom aspherical liquid micro-lenses and on-line measure their surface profiles and focal spots is developed. Experimental results show the variations of the surface profiles and focal spots of liquid lens changing with the electrostatic forces, and realize its zoom focus successfully. Fine aspherical surface profiles and focal spots of the liquid lens demonstrate the feasibility of fabricating aspherical micro-lens by using this method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 361 (2008)
Integrated Optical N×N Crossbar Network and Its Control Algorithm
Hou Peipei, Song Zhe, Li Xudong, Zhang Juan, and Liu Liren
An integrated n×n crossbar network is designed, which consists of 2×2 switches and crossbar interconnections. Considering both the phenomena of double refraction and internal double reflection, and the electro-optic effect in a crystal, all elements of n×n crossbar network are integrated in one birefringAn integrated n×n crossbar network is designed, which consists of 2×2 switches and crossbar interconnections. Considering both the phenomena of double refraction and internal double reflection, and the electro-optic effect in a crystal, all elements of n×n crossbar network are integrated in one birefringent crystal slab with electro-optic property. A control algorithm of the crossbar network is discussed, which may control the non-blocking interconnection between any input-output pair. The integrated crossbar network with low energy loss, non-blocking, is easy to assemble, insensitive to environment, well suited for use in optical networks..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 365 (2008)
Physical Optics
Description of Bottle Beam and Reconstruction of Bessel Beam Based on Diffraction Integral Theory
Liu Lan, and Wu Fengtie
The propagation formula and the intensity distribution of a bottle beam are deduced by Huygens-Fresnel diffraction integral theory. The evolution of the bottle beam is analyzed in detail and its fine structure is displayed. The influence of the focal length in focal lens on the bottle radius and bottle length is discusThe propagation formula and the intensity distribution of a bottle beam are deduced by Huygens-Fresnel diffraction integral theory. The evolution of the bottle beam is analyzed in detail and its fine structure is displayed. The influence of the focal length in focal lens on the bottle radius and bottle length is discussed. The results show that the bottle radius and bottle length increase with the increase of the focal length in focal lens. The bottle beam is generated using the system of an axicon and a focal lens in the experiment. The profiles of the transverse intensity of the bottle beam in different propagation distance are captured using the optical system of microscope and CCD camera. The results show that not only the evolution of bottle beam is depicted accurately, but the adverse factor which effects the application is also pointed out using Huygens-Fresnel diffraction integral theory. Furthermore, the self-reconstruction of Bessel beam is displayed accurately. The diffraction theory used have makes up geometric theory and interferential theory..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 370 (2008)
Quantum Optics
The Atomic Absorption in N-Type Four-Level System
Du Yingjie, and Ge Guoku
In the low-saturation limit, the property of atomic absorption resulted from the interaction between coherent light and N-type four-level system is investigated. With the numerical method, the influences of the offset of stronger light, probe-field strength and branching ratio coefficient of spontaneous decay from exciIn the low-saturation limit, the property of atomic absorption resulted from the interaction between coherent light and N-type four-level system is investigated. With the numerical method, the influences of the offset of stronger light, probe-field strength and branching ratio coefficient of spontaneous decay from excited level to lower levels to atomic absorption are discussed. The results exhibit that the coupling offset makes the atomic absorption modified in transverse orientation, and the signal offset in vertical orientation; the probe-field strength modifies the nonlinear absorption which modifies the atomic absorption, it is found that when the strength of the probe-field is far less than that of the coupling and signal field the atomic absorption is the same as the linear absorption, and it shows the characteristic of electromagnetically induced transparency; when the probe field strength continues to increase the gain emerges in the nonlinear absorption, and the atomic absorption begins to change from the transparency window to the gain one; as is known, an excited level in the system decays to two lower levels. When the branching ratio coefficient corresponding to the probe channel is near to zero, a rapid variety emerges in the atomic absorption, and when the branching ratio coefficient is equal to zero, the gain in the atomic absorption becomes infinite on the resonance of the probe field..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 375 (2008)
Quantum Mechanical Analysis of Aberration in Cr Atom Lens Generated by a Laser Standing Wave
Zhao Min, Wang Zhanshan, Ma Bin, and Li Fosheng
A grating nanostructure generated by focusing Cr atoms with nearly resonant laser standing wave (SW) atom lens was numerically simulated using the quantum-mechanical model. To improve the imaging quality of atom lens, theoretical analysis was performed to describe the aberration of atom lens, including diffractive aberA grating nanostructure generated by focusing Cr atoms with nearly resonant laser standing wave (SW) atom lens was numerically simulated using the quantum-mechanical model. To improve the imaging quality of atom lens, theoretical analysis was performed to describe the aberration of atom lens, including diffractive aberration, spherical aberration, chromatic aberration, the aberration caused by atom beam divergence angle, by magnetic sublevel structure and by isotopes. It was shown that quantum approach is more precise to describe atom focusing compared with particle-optics approach. The diffraction of atoms in laser standing wave (SW) field was explained with quantum approach. It was also shown in simulation results that aberration originates mainly from beam divergence, which is much larger than the diffractive aberration, the spherical aberration and the chromatic aberration. The aberration caused by magnetic sublevel structure and isotopes are small enough to be neglected. It is a useful method of collimating atomic beams with laser cooling to decrease the aberration caused by beam divergence. Chromatic aberration can be decreased by narrowing the statistical distribution of atomic velocity Vz..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 381 (2008)
Probabilistic Teleportation of an Arbitrary n-Particle Entangled State and Its Quantum Logic Circuit
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A scheme to probabilistically teleport an arbitrary n-particle entangled state using n pair non-maximally entangled state as the quantum channel via entanglement swapping is proposed. During the teleportation procedure, the sender Alice makes Bell-state measurements on her particle pairs and tells receiver Bob the measA scheme to probabilistically teleport an arbitrary n-particle entangled state using n pair non-maximally entangled state as the quantum channel via entanglement swapping is proposed. During the teleportation procedure, the sender Alice makes Bell-state measurements on her particle pairs and tells receiver Bob the measurement result through classical communication. According to the classical message, Bob makes corresponding unitary transformation on his own particles to reconstruct the original state. In this scheme, all particles are divided into n groups (i,ix,iy,ai,i=1～n). The advantage is that the complex unitary transformation for n+1 particles in 2n+1-dimentional Hilbert space is avaided. In each repeat operation, only simple unitary transformation for 2 particles in 4-dimentional Hilbert space is made, which considerably reduces difficulty in experiment. Then quantum logic circuit is shown for probabilistic teleportation of n-particle state and logic circuit for the particle group (i,ix,iy,ai) is given as well. Result shows that the total probability of successful teleportation is 2n∏ni=1ci2..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 387 (2008)
Spectroscopy
Influence of Covalence Effect on the Optical Spectra of d2,8 Electron Systems
Xie Linhua, and Zhu Shifu
In the investigation of optical and magnetic properties of semimagnetic semi-conductors containing transition-metal ions, one electronic d-orbital should not be treated as a pure d-orbit, instead of a mixed orbit t2g or eg because of strong covalence. In consequently, two covalent factors Nt and Ne should be introducedIn the investigation of optical and magnetic properties of semimagnetic semi-conductors containing transition-metal ions, one electronic d-orbital should not be treated as a pure d-orbit, instead of a mixed orbit t2g or eg because of strong covalence. In consequently, two covalent factors Nt and Ne should be introduced according to it. The energy matrix constructed on the mixed wave functions and including the covalent factors is called generalized energy matrix. We constructed the generalized energy matrices (45×45) for the d2/d8 electron systems. In the generalized forms, Racah electrostatic parameter A is no longer an additive constant, and d8 electron system is not identical to d2 hole system because their energy matrices are different. Furthermore, though Nt and Ne are the two different covalent factors belonging to different wave functions, their difference in numerical values should be small, because Racah electrostatic parameter A plays a great role in the calculation of energy levels when the covalence effect is considered. It means that the conventional BCΔ scheme is a good approximation. These conclusions are then extended to the application of the d-d transitions of ZnS:Ni2+, the calculated results agree well with the experimental values..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 392 (2008)
Thin Films
Calculations on Optical Properties of Cubic TiBN
Niu Jiangang, Zhao Wuzhou, Gao Wei, Wang Cuibiao, and Sun Weilian
The optical properties of cubic TiBN is important for understanding optical properties of TiBN films, monitoring and controlling the growth of TiBN films. Optical properties of cubic TiBN were investigated by using plane-wave ultrasoft pseudopotential method based on density functional theory. Electronic states densityThe optical properties of cubic TiBN is important for understanding optical properties of TiBN films, monitoring and controlling the growth of TiBN films. Optical properties of cubic TiBN were investigated by using plane-wave ultrasoft pseudopotential method based on density functional theory. Electronic states density, dielectric function, absorption coefficient, reflectance, refractive index, and extinction coefficient of cubic TiBN were calculated and analysed. density of states results demonstrates that there are peaks that attributed to the 2p states of B, which is considered to have a substantial effect on the optical absorption properties of cubic TiBN. Meanwhile, the colorimetric coordinates of cubic TiBN were calculated, based on which the corelations between colorimetric coordinates of TiBN films and technological parameters were analysed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 398 (2008)
Study on Ellipsometric Spectra of ITO Film
Sun Zhaoqi, Cao Chunbin, Song Xueping, and Cai Qi
Indium tin oxide (ITO) film with thickness of 140 nm was grown on Si substrate by sputtering method. X-ray diffraction (XRD) analysis shows that the film has the polycrystal structrue. The film was studied with reflecting spectroscopic ellipsometry in the energy range 1.5～4.5 eV. Parameterized analyses, based on LorenzIndium tin oxide (ITO) film with thickness of 140 nm was grown on Si substrate by sputtering method. X-ray diffraction (XRD) analysis shows that the film has the polycrystal structrue. The film was studied with reflecting spectroscopic ellipsometry in the energy range 1.5～4.5 eV. Parameterized analyses, based on Lorenz oscillators combined with Drude model, Graded model associated with Bruggeman effective-medium approximation model, were used to determine the optical constants and the thickness of the thin film. The results show that the indices of refraction of ITO film are in the range of 1.8～2.6 and the extinction coefficients are close to zero in the visible range and increase sharply near the wavelength of 350 nm. The optical band gap of the ITO film was estimated. A set of applicable and valuable data of dielectric coefficients and optical constants of the film were listed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 28, Issue 2, 403 (2008)
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