Journals >Acta Photonica Sinica
Contents
2012
Volume: 41 Issue 8
23 Article(s)
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Research Article
On-line Monitoring Technology for Chemical Oxygen Demand Based on Full-spectrum Analysis
FENG Wei-wei, LI Ling-wei, LI Wei-ran, SUN Xi-yan, FU Long-wen, ZHAO Guang-li, LV Ying, ZHANG Wei, and CHEN Ling-xin
A on-line monitoring system was developed for the determination of chemical oxygen demand in water based on full-spectrum analysis. In this system, least-square method was used to obtain the transmission equation between absorbance and chemical oxygen demand(COD) value by measuring absorption spectra of water with knowA on-line monitoring system was developed for the determination of chemical oxygen demand in water based on full-spectrum analysis. In this system, least-square method was used to obtain the transmission equation between absorbance and chemical oxygen demand(COD) value by measuring absorption spectra of water with known COD value, and then the established equation could inverse the COD values of the unknown water samples. For the COD determination of simulated complicated water samples, the instrumental reliability was well validated by comparing the measurement values of the analyzer with that of laboratory results. The monitoring system provided advantages of simplicity, rapidity, high precision, low consumption and environmental benignity, and was demonstrated an ideal alternative to real-time and on-line monitoring of COD in water..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 883 (2012)
Terahertz Wave Transmission in Subwavelength Metal Stripe
KONG Hui, LI Gao-fang, MA Guo-hong, HU Shu-hong, and DAI Ning
Terahertz wave transmission through the subwavelength metallic stripe arrays is investigated by terahertz time domain spectroscopy. A number of factors, including the shape of the metal structures and the periodicity of the arrays, are found to influence terahertz transmission properties. The numerical simulations baseTerahertz wave transmission through the subwavelength metallic stripe arrays is investigated by terahertz time domain spectroscopy. A number of factors, including the shape of the metal structures and the periodicity of the arrays, are found to influence terahertz transmission properties. The numerical simulations based on FDTD method show a good agreement with experimental results. The physical origin of impacting transmission is analyzed. The obtained results provide a useful reference for the fabrication of THz band-stop filters..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 888 (2012)
Free Radical and X-ray Photoelectron Spectroscopy of Moso Bamboo After UV-B Irradiation
ZHANG Wen-hui, and CHEN Qiong
Changes of the free radical and chemical components and structures of the moso bamboo irradiated with UV-B are analyzed. Electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS) are used to measure the spectrum of the free radicals and the X-ray photoelectron spectroscopy of the UV-B-irradiated bamboo pChanges of the free radical and chemical components and structures of the moso bamboo irradiated with UV-B are analyzed. Electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS) are used to measure the spectrum of the free radicals and the X-ray photoelectron spectroscopy of the UV-B-irradiated bamboo powder. The testing results reveal that when the spectral splitting factor of the bamboo free radicals (g) is 2.003 3, the intensity of free radicals increases with the irradiation time according to the law: Y=1－e－biPt; after 60 mins of irradiation with UV-B, the O/C atomic ratio in the surface bamboo increases slightly; C-C and C-H contents increase; C-O and C=O contents decrease; -O-C=O contents increase to about 3 times than the original one, which indicate in the moso bamboo surface some oxygen-containing functional groups occurr and carbon oxidation state increased..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 893 (2012)
Biological Effects of Eat Soybean Oil Based on the Fluorescence Spectroscopy
WU Qiang, LIU Ying, and HAN Cai-qin
A comparative analysis of fluorescence spectra of whole blood solution in mice having soybean oil and that in normal mice is conducted through the FLS900 steady-state fluorescence spectrometer. The results show that when using 407 nm laser to stimulate whole blood solution, it will be issued the fluorescence with peaksA comparative analysis of fluorescence spectra of whole blood solution in mice having soybean oil and that in normal mice is conducted through the FLS900 steady-state fluorescence spectrometer. The results show that when using 407 nm laser to stimulate whole blood solution, it will be issued the fluorescence with peaks at 515 nm, 556 nm and 610 nm. The fluorescence intensity of having soybean oil blood less than that of normal blood. Fluorescence polarization is also less than normal polarization of blood. The analysis shows that long-term consumption of soybean oil leads to blood cell surface area smaller that light-emitting area smaller, causing the fluorescence intensity decreases. The volume becomes smaller and enhances the ability of molecular rotation. The ability of launch fluorescence memories′ incident light is decreased and remove polarization effect is obvious enhanced so that fluorescence polarization becomes smaller. The results of the study show that long-term having soybean oil can effectively make human body blood viscosity decrease and improve blood circulation, which provide a reference for people having edible oils correctly..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 898 (2012)
Sequence Image Mosaic Based on Approximate Scale Invariant Feature Transform Descriptors
CHEN Ai-hua, YANG Ben-quan, and ZHANG Shi-qing
Through analyzing SIFT process, an approximate SIFT algorithm was proposed which changes framework of SIFT algorithm and SIFT descriptors are regarded as a kind of special Harris corners to deal with. It reduces computation time and retains advantage of SIFT algorithm. In addition, in order to enhance the accuracy of mThrough analyzing SIFT process, an approximate SIFT algorithm was proposed which changes framework of SIFT algorithm and SIFT descriptors are regarded as a kind of special Harris corners to deal with. It reduces computation time and retains advantage of SIFT algorithm. In addition, in order to enhance the accuracy of matching, a new method to refine matching couples was proposed. Experiments show that the approximate SIFT algorithm reduces computation time greatly and it does not affect the accuracy of matching. After refining matching couples, the accuracy of matching enhances greatly. The final panoramic image transits gently and has no evidence boundaries in overlapped areas..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 903 (2012)
Three-dimensional Reconstruction of Shield Structure′s Particle Field Under Debris′ Hypervelocity Impact
GE Shuang-quan, XIAO Yong-hao, and ZHAO Shi-cao
To simulate the evolution of spraying/sputtering particle field in spacecraft shield structure material under debris′ hypervelocity impact and obtain its information, a study was made on exploring three-dimensional reconstruction technology of debris′ hypervelocity impact process based on laser holographic images. The To simulate the evolution of spraying/sputtering particle field in spacecraft shield structure material under debris′ hypervelocity impact and obtain its information, a study was made on exploring three-dimensional reconstruction technology of debris′ hypervelocity impact process based on laser holographic images. The holographic image was preprocessed to divide it into 300×300 sub-images and triangular mesh algorithm was applied in sub-images of the stacked area; then the contour of the particle was extracted with Sobel operator and projected into specific space to form three-dimensional shape; the particle field evolution steps were presented based on MAXScript language. The expermental results reveal the validity of this technology, and both static reconstruction results and particle field evolution agree with the expermental images quite well. The method provides a new idea to research the spacecraft shield structure damage effects caused by debries..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 909 (2012)
Moving Object Segmentation Based on Fusion-PCNN in Compressed Domain
WANG Hui-bin, SHEN Jun-lei, WANG Xin, and ZHANG Li-li
Aiming to solve problems of the weak ability on adaptation and noise resistance in object segmentation, a novel PCNN based moving object segmentation method is presented in H.264/AVC compressed domain. First, a spatial-temporal vector filtering is used as the preprocessor to reduce the target loss rate. Then, a forwardAiming to solve problems of the weak ability on adaptation and noise resistance in object segmentation, a novel PCNN based moving object segmentation method is presented in H.264/AVC compressed domain. First, a spatial-temporal vector filtering is used as the preprocessor to reduce the target loss rate. Then, a forward-backward vector cumulative method is proposed to enhance the reliability of motion vectors. Finally, a Fusion-PCNN model is designed to fuse the cumulative motion field and the macro-block coding mode, which enhances the ability of noise resistance in object segmentation and limits the complexity. Moreover, the minimum cross-entropy is used to determine the firing conditions for an optimal self-adaptive segmentation template. Experimental results show that the proposed algorithm is outperformance and has the ability of self-adaptation and noise resistance in object segmentation. More accurate results are presented by the surveillance video..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 914 (2012)
Structural, Optical and Electrical Properties of Chromium Thin Films Prepared by Magnetron Sputtering
LIN Jian-ping, LIN Li-mei, GUAN Gui-qing, WU Yang-wei, and LAI Fa-chun
Chromium (Cr) thin films with thickness ranging from 5 nm to 114 nm were deposited on quartz substrates by the direct current magnetron sputtering. X-ray diffraction and optical spectrophotometer were employed to characterize the crystal structure and optical properties, respectively. Based on the Drude optical dielectChromium (Cr) thin films with thickness ranging from 5 nm to 114 nm were deposited on quartz substrates by the direct current magnetron sputtering. X-ray diffraction and optical spectrophotometer were employed to characterize the crystal structure and optical properties, respectively. Based on the Drude optical dielectric model, optical constants and thicknesses of the films were calculated from the transmittance and reflectance data. The sheet resistance was measured by Van der Pauw method. The results show that the films have a body-centered cubic crystalline structure. The grain size of the film increases gradually and the crystalline performance enhances as film thickness increases. When film thickness is less than 32 nm, transmittance decreases sharply, reflectance and extinction coefficient increase rapidly as the increase of thickness. When thickness is larger than 32 nm, both refractive index and extinction coefficient decrease gradually until they become stable as the thickness increases. Resistivity is the first order exponential decay when thickness increases from 5 nm to 114 nm..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 922 (2012)
Effect of Hydrogen Dilution on the Crystallization Behavior of Nanocrystalline Silicon Films and Their Growth Mechanism
YU Wei, ZHAN Xiao-zhou, LI Bin, XU Yan-mei, LI Xiao-wei, and FU Guang-sheng
Nanocrystalline silicon films were prepared by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) technique with SiH4 and H2 precursors. The micro-structure and the bonding characteristics of deposited films with different hydrogen dilution ratios were studied by Raman scattering spectroscopy and FourNanocrystalline silicon films were prepared by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) technique with SiH4 and H2 precursors. The micro-structure and the bonding characteristics of deposited films with different hydrogen dilution ratios were studied by Raman scattering spectroscopy and Fourier transform infrared absorption (FTIR) spectroscopy. The results show that with the increase of hydrogen dilution ratios, the thin film crystallization rate obviously improves to a certain extent, however, with the further increase, the film crystallization rate shows a downward trend. The analysis of infrared absorption spectra shows there is a close relationship between the silicon-hydrogen bonding model and the crystallization characteristics. With the continuous improvement of the hydrogen dilution ratios, the SiH2 bond density and the total hydrogen content in the film reduce significantly. In conditions of high hydrogen dilution ratios, the intensification of dehydrogenation reaction lead to the SiH2 bond density and the total hydrogen of film increases, and lead to a decline in the rate of film crystallization..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 927 (2012)
Fluorescence Emission Properties of N-doped ZnO Films
WANG Jin-xiang, SHEN Hong-xue, PENG Xiao-bo, WANG Yun, and LIU Yin
Using N2 as a doped source to prepare ZnO films, the N-doped ZnO films with strong (002) preferred orientation were deposited on quartz glass substrate by RF magnetron sputtering through changing the ration of O2∶N2. The result shows that the films have a main peak at 402 nm; they have other peaks at 445 nm, 524 nm witUsing N2 as a doped source to prepare ZnO films, the N-doped ZnO films with strong (002) preferred orientation were deposited on quartz glass substrate by RF magnetron sputtering through changing the ration of O2∶N2. The result shows that the films have a main peak at 402 nm; they have other peaks at 445 nm, 524 nm with the different contents of N, and the intensity of the films are different too; the peak position also produced corresponding red shift or blue shift. When O2∶N2 is 10∶15, the N doping amount of the film is the largest, and the optical performance is the best. The proposed research provides an important reference for the type of ZnO film defect and conductive..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 932 (2012)
Evolution of Phase Singularities of Flat-topped Vortex Beam Diffracted by an Aperture
CHENG Ke, XIANG An-ping, and ZHONG Xian-qiong
The analytical expression for the propagation of flat-topped vortex beam through an aperture paraxial optical ABCD system is derived. Taking aperture lens and rectangular aperture as typical examples, evolution of phase singularities between flat-topped vortex beam and flat-topped beam is comparatively studied. The effThe analytical expression for the propagation of flat-topped vortex beam through an aperture paraxial optical ABCD system is derived. Taking aperture lens and rectangular aperture as typical examples, evolution of phase singularities between flat-topped vortex beam and flat-topped beam is comparatively studied. The effect of the aperture truncation, relative off-axis displacement and beam order on evolution of phase singularities is illustrated by numerical examples. The results show that there always exists phase singularities for flat-topped vortex beam through an aperture, and the phase singularities take place in the diffracted field even the vortex core is stopped by the aperture. However, numerical calculations show that edge dislocations appear for flat-topped beam through aperture lens, and the evolution and annihilation of the edge dislocations take place with increasing of truncation parameter, while the phase singularities are not found for flat-topped beam through rectangular aperture..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 936 (2012)
Optical Breakdown Threshold in Liquid
GAO Li-min, CAO Hui, HE Wen, HAN Hui-yun, XU Zhi-qiang, and SHI Rui-min
Based on the free electron density rate equation, a plasma ellipsoid model was proposed by considering the characteristic of shaping in the focal region. Theoretical breakdown thresholds calculated by plasma ellipsoid model with modifying the electron diffusion rate were presented under the condition of shorter laser pBased on the free electron density rate equation, a plasma ellipsoid model was proposed by considering the characteristic of shaping in the focal region. Theoretical breakdown thresholds calculated by plasma ellipsoid model with modifying the electron diffusion rate were presented under the condition of shorter laser pulses. The results show that the breakdown thresholds of water calculated by plasma elliptical model are better in agreement with experimental result than other models..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 946 (2012)
Characteristics of Schmidt Prism Under the Effect of Polarization and Diffraction of Ridge
LU Jin-jun, SUN Xue-ping, and LI Xiang-yang
The polarization effect of Schmidt prism caused the two different polarization states in one beam. The field intensity distribution of diffraction of the ridge with the effect of polarization can be obtained in the way of introducing the integral equation of diffraction of ridge. It is shown that the optical field distThe polarization effect of Schmidt prism caused the two different polarization states in one beam. The field intensity distribution of diffraction of the ridge with the effect of polarization can be obtained in the way of introducing the integral equation of diffraction of ridge. It is shown that the optical field distribution distorted severely under the effect of polarization and diffraction passing through the Schmidt prism. The influence discipline of the result of diffraction with the variational azimuth of the incidence light is analyzed in detail. In the experiment, the diffraction patterns of two peaks are splited by the diffraction of zero order with the light beam emitting from a He-Ne laser passing through the Schmidt prism. The polarization effect and the diffraction of ridge have destroyed severely the light transmit both in the analysis of experiment and the theory..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 949 (2012)
Novel Prism Generating Non-diffracting-like Linear Structured Beam
WU Zhi-wei
A novel optical element is presented for solving the problems that energy of non-diffracting-like linear structured beam generated by normal triangular-section prism is evenly distributed and not suitable to be used to three-dimensional surface measurement directly and energy efficiency of central spot is lower. This eA novel optical element is presented for solving the problems that energy of non-diffracting-like linear structured beam generated by normal triangular-section prism is evenly distributed and not suitable to be used to three-dimensional surface measurement directly and energy efficiency of central spot is lower. This element is designed by gluing a platform with isosceles trapezoid section on the bottom of triangular-section prism. The beam transformation property of this element is analyzed with geometrical optics theory, and the conclusion shows that its property is the same as the combination of two normal triangular-section prisms with different bottom corner. When a plane wave illuminates on the novel optical element, non-diffracting-like linear structured beam which has higher intensity in the central spot is formed. Finally the intensity distribution is simulated by diffraction and interference theory. The results show that the conclusion of diffraction and interference theory is consistent with the conclusion of geometrical optics theory, and a better non-diffracting-like linear structured beam is generated by this novel optical element. Parameters that the central spot size of beam, non-diffracting range and so on can be adjusted easily through changing the structural parameters of the prism..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 956 (2012)
Effect of Electron Rinse on Output SNR and Electron Gain of the Microchannel Plates
CUI Dong-xu, ZHENG Shao-cheng, QIU Ya-feng, QIAN Yun-sheng, and CHANG Ben-kang
The microchannel plate (MCP) is a core device of the image intensifier for the characteristic of the electron gain. The electron rinse is a common way in the flow of the microchannel plate produce but it also changed the other characteristics of the microchannel plate. To study the effect of the electron rinse on the oThe microchannel plate (MCP) is a core device of the image intensifier for the characteristic of the electron gain. The electron rinse is a common way in the flow of the microchannel plate produce but it also changed the other characteristics of the microchannel plate. To study the effect of the electron rinse on the output signal to noise ratio and the electron gain of the microchannel plate, the method of the output signal to noise ratio test and the electron gain test based on their definition are discussed. The microchannel plate parameters test system is designed and the microchannel plate is rinsed by electron in the microchannel plate parameters test system. The output signal to noise ratio and the electron gain of the microchannel plate are tested in the process of the electron rinse at different stages. The causation of the variation of the output signal to noise ratio and the electron gain is analyzed..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 962 (2012)
Design of a High-speed Data Acquisition System Based on FPGA for Laser Radar
XIN Wen-hui, LI Shi-chun, HUA Deng-xin, SONG Yue-hui, DI Hui-ge, and ZHOU Zhi-rong
A high-speed data acquisition and preprocessing system was proposed based on FPGA for echo signal sampling of laser radar. By use of embedded DRAM and synchronous finite state-machine, the designed system, triggered by a 1 kHz excitation signal, can sample the signal at the rate of 20 MHz, and the 4 096 sampled data caA high-speed data acquisition and preprocessing system was proposed based on FPGA for echo signal sampling of laser radar. By use of embedded DRAM and synchronous finite state-machine, the designed system, triggered by a 1 kHz excitation signal, can sample the signal at the rate of 20 MHz, and the 4 096 sampled data can be accumulated correspondingly more than 5 000 times for the purpose of filtering background noise. The completed system was applied in a Mie scattering laser radar, which can achieve the spatial and temporal resolution of 7.5 meter and the detection range of 30 km..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 967 (2012)
Impact of Buffer Interlayer on the Performance of Heterojunction Organic Photovoltaic Devices
LI Wei-min, GUO Jin-chuan, and ZHOU Bin
The CuPc/buffer interlayer/C60 heterojunction organic photovoltaic devices are fabricated by inserting a MoO3 or RB interlayer and investigated the impact of buffer interlayer on the performance of heterojunction organic photovoltaic devices. The results suggest that OPV with the buffer interlayer has higher open-circuThe CuPc/buffer interlayer/C60 heterojunction organic photovoltaic devices are fabricated by inserting a MoO3 or RB interlayer and investigated the impact of buffer interlayer on the performance of heterojunction organic photovoltaic devices. The results suggest that OPV with the buffer interlayer has higher open-circuit voltage and power conversion efficiency, lower short-circuit current density and fill factor. The open-circuit voltage increases from 0.39 V to 0.58 V and 0.55 V, respectively, and the power conversion efficiency reaches 0.44%, in comparison with a power conversion efficiency of 0.36% for OPV without interlayer. The short-circuit current density decreases from 1.92 mA/cm2 to 1.77 mA/cm2 and 1.81 mA/cm2, and from 0.48 to 0.43 and 0.44 in fill factor, respectively. Further research shows that the short-circuit current density strongly depends on the thickness of buffer layer. The short-circuit current density increases when the interlayer thickness is small, while it gradually decreases as the buffer layer thickness increasing. When the interlayer thickness is 10 nm, the short-circuit current density decreases to 0.35 mA/cm2. The open-circuit voltage enhances as the buffer layer thickness increasing, from 0.43 V with 1 nm interlayer to 0.63 V 10 nm interlayer. Open-circuit voltage enhancement and the short-circuit current density decrease are studied according to the integer charge transfer model and interfacial energy level theory, which provide a research foundation for the performance improvement of organic solar cells..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 972 (2012)
Far-field Characteristics of Silver Nanodisk Optical Antenna
LI Hong-guang
The near-field distribution of silver nanodisk optical antenna was calculated with Finite-Difference Time-Domain method. The influence to the far-field characteristics by different parameters such as the distance between nanodisk and dipole, thickness and radius of nanodisk, was discussed. The research demonstrated thaThe near-field distribution of silver nanodisk optical antenna was calculated with Finite-Difference Time-Domain method. The influence to the far-field characteristics by different parameters such as the distance between nanodisk and dipole, thickness and radius of nanodisk, was discussed. The research demonstrated that when the dipole was placed vertically beneath the nanodisk, the variation of thickness or radius could lead to new radiation mode in the far-field pattern and give rise to the enhancement of directivity gain. Through the observation and analysis to near-field, it could be obtained that the new radiation mode was caused by the high order localized surface plasmon(LSP) mode. The optimization results pointed out that as the background material was set as GaN, for the sake of producing high order LSP mode, the suitable distance between nanodisk and dipole was 40 nm. Furthermore, in order to effectively support the high order LSP mode, the thickness and radius of nanodisk were at least 30 nm and 100 nm respectively. These results provided a theoretical reference to master the characteristics of nanodisk optical antenna as well as the practical application in optical devices..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 977 (2012)
Design of High-drop Hole-type Photonic Crystal Ring Resonators
XU Xiao-fu, HAO Xiao-long, JIANG Jun-zhen, LI Hui, QIU Yi-shen, and QIANG Ze-xuan
A high-drop air-hole-type photonic crystal ring resonator (PCRR) was proposed based on two-dimensional square lattice configuration. The single mode operation can be realized by compressing the width of bus waveguide. The impact of number of rows of holes on the propagating field intensity distribution was also analyzeA high-drop air-hole-type photonic crystal ring resonator (PCRR) was proposed based on two-dimensional square lattice configuration. The single mode operation can be realized by compressing the width of bus waveguide. The impact of number of rows of holes on the propagating field intensity distribution was also analyzed. The physical parameters, such as dropping wavelength, dropping efficiency and spectral quality factor (Q) affected by changing the localized refractive index of inner ring and coupling strength between bus waveguide and PCRR, were numerically demonstrated based on two-dimensional (2D) finite-difference time-domain (FDTD) technique. It shows that 99% dropping efficiency and 379 Q can be obtained at 1 528.1 nm signal channel when the width of bus-waveguide and coupling strength are 0.7-periodicity and 0-periodicity, respectively. On the other hand, when the coupling strength increases to 1 periodicity, the Q can be improved by 1 397 with the decreased dropping efficiency by 89%. Besides, the dropping wavelength can be linearly increased with the increase of localized refractive index of inner ring..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 982 (2012)
Resonance Theory of the Total Reflection Tunnel Effect of Half Infinite Period Photonic Crystal
LIU Qi-neng
The resonance mechanism sets up a resonant cavity model of 1D half infinite period photonic crystal, and takes advantage of resonance conditions to infer the analytical formulas of the wavelength deduced by the total reflection tunnel effect. The physical mechanism of the total reflection tunnel effect of 1D half infinThe resonance mechanism sets up a resonant cavity model of 1D half infinite period photonic crystal, and takes advantage of resonance conditions to infer the analytical formulas of the wavelength deduced by the total reflection tunnel effect. The physical mechanism of the total reflection tunnel effect of 1D half infinite period photonic crystal is explained. By using the formulas, the wavelength changes related to order number, thickness of resonant cavity, as well as the incident angle, are analyzed and the change law of the total reflection tunnel effect is explained successfully. Resonance theory results and dispersion method results are compared and their results are the same..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 986 (2012)
Incoherently Coupled Spatial Soliton Pairs in Photorefractive Crystals Illuminated by E-polarized Incoherent Uniform Back-ground Irradiation with a Divider Resistance
JI Xuan-mang, JIANG Qi-chang, and LIU Jin-song
In order to study the universal theory of incoherently coupled spatial solitons pairs in photorefractive crystals, the theory of incoherently coupled soliton pairs based on the one-photon photorefractive effect is established in one-photon photovoltaic photorefractive crystals illuminated by e-polarized incoherent unifIn order to study the universal theory of incoherently coupled spatial solitons pairs in photorefractive crystals, the theory of incoherently coupled soliton pairs based on the one-photon photorefractive effect is established in one-photon photovoltaic photorefractive crystals illuminated by e-polarized incoherent uniform back-ground irradiation with a divider resistance under steady-state conditions. The numerical results show that these soliton pairs can be established by two carrier beams which share the same polarization, wavelength and are mutually incoherent. When these incoherent coupled soliton pairs propagate together, two components can propagate stably in photorefractive crystal. The 14 kinds of incoherently coupled spatial soliton pairs can be obtained from this theory by adjusting the value of the divider resistance, e-polarized back-ground irradiation, the biased electric field and photovoltaic electric field. The proposed studies have great significance to the photorefractive spatial soliton theory system..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 991 (2012)
Numerical Analysis for High Order Nonlinear Optical Pulse Progration on Slip-step Wavelet Method
ZHONG Ming-yu, LIU Dong-feng, and HU Chang-jun
Using wavelet transform to replace Fourier transform to solute higher-order nonlinear Schrodinger equation, provides it as another tool, it improves the operation speed.Analyzed the high-order nonlinear Schrodinger equation general solution form.By using Db10 wavelet, obtained the matrix corresponding to differential oUsing wavelet transform to replace Fourier transform to solute higher-order nonlinear Schrodinger equation, provides it as another tool, it improves the operation speed.Analyzed the high-order nonlinear Schrodinger equation general solution form.By using Db10 wavelet, obtained the matrix corresponding to differential operator and dispersive operator,also obtained the split-step wavelet method algorithm formula. Derivate the dispersion operator and the signal in wavelet domain multiplied by the approximate calculating formula, the split-step Fourier method need more complex multiplication times than the split-step wavelet method, at the same time that increase the speed of operation cost the computation precision. Finally take the split-step Fourier method as standard, analyzed the split-step wavelet method error, the results show that, for the first order soliton, between the split-step wavelet method and split-step Fourier method relative error fluctuate around 1.2%..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 999 (2012)
Self-similar Propagation of Linearly Chirped Pulses in Fibers with Longitudinal Gain Profile
REN Li-ping
Nonlinear Schrdinger Equation is a basic equation for investigating the propagation of optical pulses in fibers. By using the split-step Fourier method, self-similar propagation of linearly chirped pulses in fibers with longitudinal gain profile is studied. It is found that, because the self-phase modulation and groupNonlinear Schrdinger Equation is a basic equation for investigating the propagation of optical pulses in fibers. By using the split-step Fourier method, self-similar propagation of linearly chirped pulses in fibers with longitudinal gain profile is studied. It is found that, because the self-phase modulation and group velocity dispersion respectively play the main roles at different propagation distances when the signs of the group velocity dispersion coefficient and the chirp coefficient are the same, no matter what the shapes of the input pulses are, the pulses will be compressed during propagation, and with the further increasing of the propagation distance, the compressed pulses will be broadened again. The intensity distributions of the Hermite-Gaussain input pulse as well as the sine input pulse are symmetric, while that of the Laguerre-Gaussian input pulses deflect during propagation obviously because of energy exchange. When the signs of the group velocity dispersion coefficient and the chirp coefficient are different, group velocity dispersion plays the main role, and the pulse is always broadened during propagation. The results may provide a new theoretical foundation and a new method for the fabrication of pulse compressors, amplifers and the development of a new source for THz modulated beams..
Acta Photonica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 41, Issue 8, 1004 (2012)
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