Contents
2005
Volume: 25 Issue 8
28 Article(s)
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Atmospheric Optics and Oceanic Optics
Numerical Analysis of Intensity Fluctuation Scale Characteristics in Space Laser Communication
[in Chinese], [in Chinese], and [in Chinese]
The intensity fluctuation in space laser communication is analyzed quantitatively by using numerical simulation method, the relation of the intensity correlative scale with the atmospheric coherence length is obtained. And the referenced factors of ascertaining optimum receiving aperture are discussed. The optimum receThe intensity fluctuation in space laser communication is analyzed quantitatively by using numerical simulation method, the relation of the intensity correlative scale with the atmospheric coherence length is obtained. And the referenced factors of ascertaining optimum receiving aperture are discussed. The optimum receiving aperture is defined base on the ITU-T, and the relation of optimum receiving aperture with atmospheric coherent length is educed, the result shows that the optimum receiving aperture is greatly increasing as the atmospheric coherence distance decreasing. When focused laser beam is used in space laser communication, at the strong atmospheric turbulent effect, for example r0 about 4 cm, only the receiving aperture approaches 5 times diameter of Airy spot, the lowest ITU-T demand can be satisfied..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1009 (2005)
Finite-Element Analysis of Birefringence in Circular-Core Side-Hole Fiber
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The research results of the intrinsic birefringence of the circular-core side hole fiber are reported. On the basis of the study on the production mechanism and calculation principles of the intrinsic birefringence of the side hole fiber, the finite element method is used to analyze the interior stresses distribution aThe research results of the intrinsic birefringence of the circular-core side hole fiber are reported. On the basis of the study on the production mechanism and calculation principles of the intrinsic birefringence of the side hole fiber, the finite element method is used to analyze the interior stresses distribution and the birefringence values of the circular-core side hole fiber. The research results indicate that the geometrical birefringence of the circular-core side hole fiber can be neglected, and the birefringence mainly relies on the stress birefringence; the stresses distributions in the core and cladding field have changed greatly because of the presence of the side holes. The conclusion is put forword that the fast axis of the circular-core side hole fiber is parallel to the link line of the two holes. The influence of different physical dimensions of the holes on the intrinsic birefringence of the side hole fiber is also discussed and the results show that the intrinsic birefringence of the circular-core side hole fiber with round holes increases exponentially with the angle of side holes. The birefringence can be improved through increasing the radius of the side holes and reducing the distance between the core and the side hole..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1013 (2005)
Fiber Optics and Optical Communications
Spectral Characteristics of the Cascaded LongPeriod Gratings
[in Chinese], and [in Chinese]
The transmission spectra of cascaded longperiod grating (LPG) are analyzed using transfer matrix method. The effects of the length,position and loss coefficient of the fiber that connects the LPGs on the cascaded LPG spectral characteristics are discussed. Through numerical analysis, it is shown that the spectra of caThe transmission spectra of cascaded longperiod grating (LPG) are analyzed using transfer matrix method. The effects of the length,position and loss coefficient of the fiber that connects the LPGs on the cascaded LPG spectral characteristics are discussed. Through numerical analysis, it is shown that the spectra of cascaded LPG and phase shifted LPG have great consistency when the length of the cascading fiber is small or the cascading position is near the end of the cascaded LPG. If other losses are not considered, the amount of transmission loss keeps constant no matter how the length of the cascading fiber changes. The calculation and analysis results also show that if the loss coefficient of the cascading fiber's cladding mode is large enough, the spectra of cascaded LPG can be dealt as incoherent cascading of two LPG spectra, which provides an efficient way to the optimization and design of LPG gain equalizer..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1019 (2005)
Theoretical Study on Electrooptic Effect and Elasto-Optic Effect in Chirped Fiber Grating with Uniaxial Crystal Cladding
[in Chinese], and [in Chinese]
A new type of chirped fiber grating with cladding made of uniaxial crystal material whose optical axis is parallel to the axis of grating, i.e., z-axis, is proposed. Electrooptic effect and elasto-optic effect in this kind of fiber gratings are theoretically analyzed based on coupled-mode theory and transfer martrix. IA new type of chirped fiber grating with cladding made of uniaxial crystal material whose optical axis is parallel to the axis of grating, i.e., z-axis, is proposed. Electrooptic effect and elasto-optic effect in this kind of fiber gratings are theoretically analyzed based on coupled-mode theory and transfer martrix. It was found that Bragg wavelength λB and the reflective spectra of the chirped grating can be changed by the electric field and the strain applied to the fiber grating cladding along z-axis. The curves of Bragg wavelength λB as a function of an external electric field or the strain are obtained respectively for three kinds of uniaxial crystals as the grating cladding. The calculated results indicate that when the axial electric field applied to the grating cladding varies from 1×107 V/m to 8×107 V/m, λB has the decrease of 0.12 nm, and when the applied strain varies from 0 to 0.04, λB has the decrease of 0.45 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1025 (2005)
Imaging Systems
Study on Imaging of Dual Three Sub-Apertures Design
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A sparse-aperture design named dual three sub-apertures, which is composed of nine sub-apertures, is proposed. The pupil function, analytical formulas of its corresponding modulation transfer function (MTF) and three configuration models have been given. The comparisons among the MTFs of three models are made. The featA sparse-aperture design named dual three sub-apertures, which is composed of nine sub-apertures, is proposed. The pupil function, analytical formulas of its corresponding modulation transfer function (MTF) and three configuration models have been given. The comparisons among the MTFs of three models are made. The features of three kinds of configuration of dual three sub-apertures is illuminated. The maximum cut-off frequency and equivalent diameters under the different filling factors of dual three sub-apertures for model Ⅰ are given by calculating. The image quality is evaluated by two kinds of method. The image simulations, noisy image restorations and reconstructuring image show that the image spatial resolution of dual three sub-apertures approaches the resolution of encircled aperture, the image quality degrades with the decreasing of filling factor. The image quality can be improved using Wiener filtering. The sparse-aperture system of dual three sub-apertures has the advantages of flexible configuration and easy fabrication..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1030 (2005)
Triangle Orientation Discrimination Threshold Curve Prediction Based on Staring Thermal Imaging Simulation
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
For the effective performance evaluation of staring imaging system, the signal response model of staring imaging system is established according to the conversion mechanism of infrared radiometric signal in the imaging process. The transfer function of imaging system is modeled using the linear system theory and sampliFor the effective performance evaluation of staring imaging system, the signal response model of staring imaging system is established according to the conversion mechanism of infrared radiometric signal in the imaging process. The transfer function of imaging system is modeled using the linear system theory and sampling theory, and the noise is characterized with the three-dimensional noise model. Based on staring imaging system modeling, the triangle pattern simulation images with different differential temperatures and different sizes are generated. Triangle pattern simulation images with different stimulus intensities are observed, and the correct discrimination probability of the triangle pattern orientation is obtained utilizing the statistical method. The psychometric function-Weibull function is used to fit the probability data, and the triangle orientation discrimination (TOD) threshold prediction curve is achieved. The experimental results indicate that the triangle orientation discrimination threshold prediction curve is reasonable..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1036 (2005)
Size Effects of Sub-Aperture on Imaging of Linear Array of Optical Synthetic Aperture
[in Chinese]
Positions and diameters of sub-aperture in optical synthetic aperture array are two important factor for imaging. The characteristics of point spread function, optical transfer function and diffraction image of several different optimized linear array configuration of optical aperture synthesis with aberration-free arePositions and diameters of sub-aperture in optical synthetic aperture array are two important factor for imaging. The characteristics of point spread function, optical transfer function and diffraction image of several different optimized linear array configuration of optical aperture synthesis with aberration-free are discussed by using an approach based on ratio of diameter of sub-aperture to length of arrays. The results of simulated computation show that cover of spatial frequencies for optical transfer function are very different for different position of sub-aperture. The bigger the diameter of sub-aperture is, the more complete the spatial frequency covers. But when the ratio exceeds some extent, the spatial frequencies will be redundant and cost of system construction will increase. Besides, increase of sub-aperture can decrease the intensity of the ghost images and intensified the quality of imaging. The results show that the factors of diameter of sub-aperture and total length of arrays must be taken into account in the optimizations..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1042 (2005)
Instrumentation, Measurement and Metrology
The Radiation Exchange between the Space and the Absolute Radiometer Along with the Solar Observation on Spacecraft
[in Chinese], [in Chinese], and [in Chinese]
The radiation exchange between the cold space (4 K) and the absolute radiometer (300 K) with wide field of view mounted on satellite is analysed when the sun is observed. That is the radiometer export radiation to space. It is equal to “minus radiation” received the by radiometer. When the field of view is wide, the “mThe radiation exchange between the cold space (4 K) and the absolute radiometer (300 K) with wide field of view mounted on satellite is analysed when the sun is observed. That is the radiometer export radiation to space. It is equal to “minus radiation” received the by radiometer. When the field of view is wide, the “minus radiation” of absolute radiometer could not be ignored. The “minus radiation” which is full of its field of view is received, so the data measured are less than the pure solar irradiance, and the solar irradiance is the value that the “minus radiation” adding the original data. The three-step work flow chart of absolute radiometer that can measure the “minus radiation”, solar irradiance and electric compensation has been investigated. The absolute radiometer of solar constant monitor with wide field of veiw mounted on Shenzhou-3 spaceship measured solar constant in this work flow chart. The measured “minus radiation” value is equal to calculated value..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1048 (2005)
Brillouin Optical Time Domain Analysis Distributed Optic-Fiber Sensor Based on Microwave Electrooptic Modulation
[in Chinese], [in Chinese], and [in Chinese]
The technique of Brillouin optical time domain analysis distributed optical fiber sensing has been presented and demonstrated experimentally, which is based on electrooptic modulation. Microwave electrooptic modulation is adopted to produce frequency-adjustable probe light, which is interacted with pulsed pump light viThe technique of Brillouin optical time domain analysis distributed optical fiber sensing has been presented and demonstrated experimentally, which is based on electrooptic modulation. Microwave electrooptic modulation is adopted to produce frequency-adjustable probe light, which is interacted with pulsed pump light via stimulated Brillouin scattering, when the optical frequency difference between probe and pump light is near the fiber's Brillouin frequency shift. The detecting signal of probe light is processed by digital BOXCAR and computer, then the fiber's Brillouin frequency shift could be obtained, and the distributing temperature or stress of the fiber could be calculated. The experimental procedures and results are presented. A laboratory system of 25 km distributed Brillouin optical time domain analysis temperature sensor is achieved, with 3 ℃ in temperature resolution, and 5 m in spatial resolution..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1053 (2005)
Digital Shadow Moiré Method with Phase-Shifting Based on Liquid Crystal Display Projector
[in Chinese], [in Chinese], and [in Chinese]
Shadow moiré is one of the simple optical techniques for topography and out-of-plane displacement measurement. The sensitivity of this procedure is in the range of 1～100 μm in best cases. Introduction of a phase-shifting procedure may further give a better resolution. A new digital shadow moiré method with diShadow moiré is one of the simple optical techniques for topography and out-of-plane displacement measurement. The sensitivity of this procedure is in the range of 1～100 μm in best cases. Introduction of a phase-shifting procedure may further give a better resolution. A new digital shadow moiré method with digital phase-shifting based on liquid crystal display (LCD) projector is presented. One of four computer-generated phase-shifting fringe patterns, with using LCD projector, is projected on the surface of object to be tested while all fringe patterns are projected on a plate for generating phase-shifting moiré fringes. The projected fringe patterns are captured in real time by a charge coupled device (CCD) camera. This new method provides many advantages in performing topography and out-of-plane displacement measurement. First, the spatial line pitch and phase step are readily adjusted to suit the measurement precision. Second, the measuring speed is relatively fast and suit for dynamic testing because the digital phase shifting is no time-consuming comparing with other phase-shifting techniques. The experimental result on a cantilever beam well demonstrates the validity of the new method..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1057 (2005)
Frequency Domain Analysis of Surface Figure Fitting Based on Zernike Polynomials
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Obtaining the spectrum of Zernike polynomials is the key to fit the surface errors by Zernike polynomials correctly. The Fourier transform equation of Zernike polynomials is derived to analyze both the radial spectrum and the angular spectrum information of Zernike polynomials with different orders. The maximum radial Obtaining the spectrum of Zernike polynomials is the key to fit the surface errors by Zernike polynomials correctly. The Fourier transform equation of Zernike polynomials is derived to analyze both the radial spectrum and the angular spectrum information of Zernike polynomials with different orders. The maximum radial spatial frequency and angular spatial frequency of the surface errors that can be effectively generated by finite-term Zernike polynomials is obtained. Based on frequency domain theory, local errors with different apertures are fitted using Zernike polynomials and experiments on optical elements are made using Zygo interferometer. The results show that the fitting errors would increase drastically when the radial spatial frequency or the angular frequency of the error exceeds the spectrum range which could be described by Zernike polynomials..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1062 (2005)
Method of CCD Scan for Collimation Testing
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A new wavefront analysis method is proposed for collimation testing of laser beam. Based on the definition of wavefront rise wavefront analysis method of CCD scan is introduced. Wavefront rise is obtained by measuring the distance between the two same fiducial diffraction planes of the sampled wave. Therefore, the degrA new wavefront analysis method is proposed for collimation testing of laser beam. Based on the definition of wavefront rise wavefront analysis method of CCD scan is introduced. Wavefront rise is obtained by measuring the distance between the two same fiducial diffraction planes of the sampled wave. Therefore, the degree of collimation is determined. The principle of measurement and simulated fiducial diffraction patterns are given before experiment is made. The results demonstrated the feasibility of the method. The method holds a definite advantage in simplicity, and it is applicable for checking the degree of collimation of noncollimated wave..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1067 (2005)
Lasers and Laser Optics
Laser-Diode-Pumped Acoustooptic Q-Switched Tm,Ho∶YLF Laser
[in Chinese], [in Chinese], and [in Chinese]
A laser-diode pumped actively Q-switched Tm,Ho∶YLF laser is reported. The rate equation of Tm,Ho∶YLF Q-switched laser is given including the energy transfer upconversion effect and the analytical expression of initial number of reversion particles is obtained. The influence of energy transfer upconversion effect on theA laser-diode pumped actively Q-switched Tm,Ho∶YLF laser is reported. The rate equation of Tm,Ho∶YLF Q-switched laser is given including the energy transfer upconversion effect and the analytical expression of initial number of reversion particles is obtained. The influence of energy transfer upconversion effect on the number of upper level reversion particles is analyzed. At room temperature, 2 μm wavelength pulse output is realized. Average output power, single pulse energy and pulse width are measured at different pump power and different repetition rates. The average output power of 189 mW and a optical-optical efficiency of 6.8% are obtained at the repetition rate of 9 kHz and the pump power of 2.8 W. The maximum single pulse energy of 65 μJ and peak power of 0.17 kW are obtained at the repetition rate of 1 kHz..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1072 (2005)
Generation of Wavelength Tunable Optical Ultrashort Pulse with Simple Scheme and High-Quality
[in Chinese], [in Chinese], and [in Chinese]
Wavelength tunable optical ultrashort pulse generation by the use of a gain-switched Fabry-Pérot laser diode in a self-seeding simple scheme is presented. The laser external cavity consists of two fiber Bragg gratings (FBG) connected in series, an erbium-doped fiber amplifier (EDFA), an optical coupler and two cirWavelength tunable optical ultrashort pulse generation by the use of a gain-switched Fabry-Pérot laser diode in a self-seeding simple scheme is presented. The laser external cavity consists of two fiber Bragg gratings (FBG) connected in series, an erbium-doped fiber amplifier (EDFA), an optical coupler and two circulators, which provides a mode selective and intensity controllable feedback to the laser diode. The system is simple and efficient, and sidemode suppression ratio (SMSR) of the output pulses obtained is close to or larger than 40 dB within a relatively wide wavelength-tuning range of 24 nm. The whole operating wavelength region is about 28.2 nm, between 1521.8 nm and 1550.0 nm, the SMSR obtained is better than 35 dB. The full width at half maximum (FWHM) of the pulse width is about 140～260 ps, and the FWHM of spectrum at different wavelength for any pulses is about 0.1 nm..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1077 (2005)
Materials
Photoluminescence Studies of Nanometer Ce3+-Doped SiO2 Synthesized by Sol-Gel Method
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Nanometer Ce3+-doped SiO2 was prepared by sol-gel method, and it is photoluminescent property was studied. The structure of samples was found to be amorphous with powder size between 20 and 30 nm determined by X-ray diffraction (XRD) and transmission electron microscope (TEM) techniques. The photoluminescence spectrum Nanometer Ce3+-doped SiO2 was prepared by sol-gel method, and it is photoluminescent property was studied. The structure of samples was found to be amorphous with powder size between 20 and 30 nm determined by X-ray diffraction (XRD) and transmission electron microscope (TEM) techniques. The photoluminescence spectrum of the Ce3+-doped SiO2 annealed at 450 ℃ shows a very strong UV luminescence band at 346 nm under 230 nm excitation. A wide band with multipeaks was also observed under the excitation of 380 nm. Compared with the Cu2+-doped and undoped silica a conclusion can be drawn that the UV luminescence band at 346 nm is originated from the natural defect of silica but not the characteristic luminescence of d-f transition of Ce3+. Based on the relationship of 346 nm band emission intensity with the heat treatment temperature and the concentration of Ce3+ ions in SiO2, the structure model of the 346 nm band was discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1081 (2005)
Effects of ZnO on the Character and Optical Properties of Eu∶LiNbO3 Crystal
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The growth of LiNbO3 crystals co-doped with Zn2+, Eu3+ ions with different concentrations by Bridgman method was obtained by means of the feed materials with proper composition mole fraction [x(Li2O)=48.6%, x(Nb2O5)=51.4%]. The X-ray diffraction (XRD), excitation, emission and phonon side band spectra of the upper and The growth of LiNbO3 crystals co-doped with Zn2+, Eu3+ ions with different concentrations by Bridgman method was obtained by means of the feed materials with proper composition mole fraction [x(Li2O)=48.6%, x(Nb2O5)=51.4%]. The X-ray diffraction (XRD), excitation, emission and phonon side band spectra of the upper and lower parts of crystals were measured. The doping content of ZnO takes great effects on the distributing concentration of Eu3+ ion LiNbO3 crystal. When 3% of ZnO in mole fraction is doped, the Eu3+ ions are suppressed effectively to enter LiNbO3 crystal lattice, but in 6% mole fraction, the effect becomes weaker. The reasons for the concentration changes of Eu3+ ions can be interpreted by the suppressing effect of ZnO on the incorporation of Eu3+ ions and the change of distribution coefficient of Zn2+ as its incorporating content. In the meantime, the phonon sideband spectra of Zn-incorporated samples were recorded..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1087 (2005)
Experimental Research on Influence of Packing Materials of White LED on Its Luminous Decay
[in Chinese], and [in Chinese]
Some packing materials have been tested contrastively including different brackets, glues for fixing chips, fluorescent powder and glues for mixing fluorescent powder, in order to confirm their influence on luminous decay performance of white LED. It is found out from test that, the efficiency of white LED using copperSome packing materials have been tested contrastively including different brackets, glues for fixing chips, fluorescent powder and glues for mixing fluorescent powder, in order to confirm their influence on luminous decay performance of white LED. It is found out from test that, the efficiency of white LED using copper brackets is higher than iron brackets, moreover, the light decay is lower about 10%. The life of white LED using silver glues is longer than using epoxy resins, but initial luminous flux is much lower by 1/3. Different fluorescent powders have different influence on the luminous decay of white LED. The life of white LED using epoxy resins to mix fluorescent powder is shorter than silica gel, but initial luminous flux is higher about 25%. It can be concluded that, different glues for fixing chips and brackets make the thermal resistance from PN junction to bracket change, solidified temperature is distinct during packing when different glues for mixing fluorescent powder have been used, and fluorescent powders have the phenomenon of luminous decay, all of those affect the white LED' life time. Therefore, the materials should be selected synthesizing many factors during designing and packing, based on the importance of initial luminous flux, light decay and drift of color temperature..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1091 (2005)
The Study of Electrooptical Characteristics of Polymer Dispersed Liquid Crystal at 1550 nm
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Some experiments have been performed to research the electrooptical characteristics of polymer dispersed liquid crystal (PDLC) with different recipes and preparation techniques at 1550 nm. Results of the research show that the liquid crystal content and surfactant impact the electrooptical characteristics PDLC greatly,Some experiments have been performed to research the electrooptical characteristics of polymer dispersed liquid crystal (PDLC) with different recipes and preparation techniques at 1550 nm. Results of the research show that the liquid crystal content and surfactant impact the electrooptical characteristics PDLC greatly, and with about 50% LC content, relatively better electrooptical curves may be obtained at 1550 nm. Base on these experiments, some comparatively suitable recipes and preparation techniques are selected to manufacture PDLC tunable attenuator samples. As a result, recipe with the mass ratio as w(DHPA)∶w(E7)∶w(RB)∶w(NVP)∶w(NPG)＝100∶100∶3∶2∶1.5 is adopted and fabricated the PDLC optical tunable attenuator samples. The average insertion loss is 2.3 dB at the wavelength of 1550 nm with the output power 223 μW, and the attenuation range is about 13 dB, voltage linear working range of the device is from 20 V to 70 V..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1095 (2005)
Microscopy
Photon Scanning Tunneling Microscope Combined with Atomic Force Microscope
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The development course of Photon Scanning Tunneling Microscopy (PSTM) is introduced. There are two difficult problems in first generation (with single beam) PSTM, which are the spurious image and the mixture of optical image with topography of sample in PSTM imaging. With the method of π symmetry two beams lighting to The development course of Photon Scanning Tunneling Microscopy (PSTM) is introduced. There are two difficult problems in first generation (with single beam) PSTM, which are the spurious image and the mixture of optical image with topography of sample in PSTM imaging. With the method of π symmetry two beams lighting to eliminate the optical spurious image, and the method of AF/ PSTM separating image was used to separate the optical image from topography image of sample. The patent instrument named AF/PSTM (atomic force/photon scanning tunneling microscope) have been successfully developed, with which two AFM images (topography and phase images) and two PSTM images (transmissivity and refractive index images) of sample in once scanning are obtained. The AF/PSTM can limit the spurious effects due to non-isotropic illumination with single beam and can separate the refractive index image and transmissivity image from topography image..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1099 (2005)
Nonlinear Optics
Stimulated Raman and Brillouin Scattering in Oxygen Pumped by a Nd∶YAG Laser at 355 nm
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Experimental results of reported stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) in oxygen pumped by a pulsed Nd∶YAG laser at 355 nm in two different bandwidth cases are reported. In broad band (～1 cm-1) case, only forward SRS was measured while backward scattering was not observed. Maximum Experimental results of reported stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) in oxygen pumped by a pulsed Nd∶YAG laser at 355 nm in two different bandwidth cases are reported. In broad band (～1 cm-1) case, only forward SRS was measured while backward scattering was not observed. Maximum energy conversion efficiencies of 22% and 8%, respectively for the first and second Stokes, were obtained. In narrow band (～0.003 cm-1) case, both forward and backward SRS and SBS were observed, but most of input pump energy was converted to SBS with conversion efficiency of 67%. The pulse shapes of various scattering components were measured in these two cases. In narrow band case the pulse width for backward SRS and SBS were respectively narrowed to 1.5～2.3 ns, no more than 1/3 of input pump pulse width, so SBS peak power was much larger than that of pump laser. The competition among forward and backward SRS and SBS in oxygen was discussed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1105 (2005)
Study on One-Dimensional Gray Photovoltaic Spatial Solitons and Their Stability
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on the beam propagation dynamic equation with the photovoltaic effect of the uniform background illumination, it is theoretically demonstrated that gray photovoltaic spatial solitons can exist in photovoltaic media with positive refractive index perturbation. When the beam is gray, the transverse phase profile vaBased on the beam propagation dynamic equation with the photovoltaic effect of the uniform background illumination, it is theoretically demonstrated that gray photovoltaic spatial solitons can exist in photovoltaic media with positive refractive index perturbation. When the beam is gray, the transverse phase profile varies in the fashion of (s)=vη-∫η0y-2()d, where v is the transverse velocity, η is a dimensionless coordinate, and y(η) is a normalized optical field amplitude. The impact of the grayness parameter m, the normalized intensity at infinity, the ratio (R) of effective Glass constants of the background beam to that of the signal beam on the FWHM and transverse velocity of gray solitons are discussed. The analysis of stability properties of these solitons is also given. When the grayness m=0, these gray solitons degenerate to photovoltaic dark solitons automatically..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1111 (2005)
OPTOELECTRONICS
Growth and Microstructure Analysis of PMMA Photonic Crystal
[in Chinese], and [in Chinese]
Metal/semiconductor photonic crystals (PCs) will be applied in important national defense technology, the research focus of its growth is to how to assemble the PMMA microsphere into colloidal crystal. Based on the well-established vertical deposition method and isothermal evaporation processing, a controllable verticaMetal/semiconductor photonic crystals (PCs) will be applied in important national defense technology, the research focus of its growth is to how to assemble the PMMA microsphere into colloidal crystal. Based on the well-established vertical deposition method and isothermal evaporation processing, a controllable vertical deposition (CVD) method was developed to prepare the photonic crystal in the study. The highly monodisperse PMMA colloid particles with size of 294 nm and 345 nm were synthesized from the MMA and azo-initiator and assembled into photonic crystals by the technology; it was shown from the SEM observation of the sample that the bulk structure of the crystal has a high periodical array, the perfect order zone is above 20 μm; the surface structure of the crystal is completely flat and has only two defects in the 3 μm×5 μm order zone. It was concluded from the growth interface analysis that during the process of controllable vertical deposition, the crystals grow by continuous growth mechanism and the growing crystals have rough interface..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1117 (2005)
Research on Two-Photon Absorption Enhancement of CdS in One-Dimensional Photonic Band Gap Structures
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
One-dimensional photonic crystals (1D PC) with single CdS defect layer in TiO2/SiO2 dielectric thin films stack with different periods and structural parameters were fabricated by vacuum deposition. Two-photon absorption (TPA) of the CdS defect layer in the photonic crystals was investigated by pump-probe measurement. One-dimensional photonic crystals (1D PC) with single CdS defect layer in TiO2/SiO2 dielectric thin films stack with different periods and structural parameters were fabricated by vacuum deposition. Two-photon absorption (TPA) of the CdS defect layer in the photonic crystals was investigated by pump-probe measurement. Experimental results show a significant enhancement of TPA coefficient in the CdS defect layer in one-dimensional photonic crystal. Different magnitude of enhanced two-photon absorption coefficient of CdS defect layer in one-dimensional photonic crystal with different photonic band gap has been observed. The enhanced two-photon absorption effect results from the electric field enhancement due to the light localization in the CdS defect layer. The electric field enhancement in defect laser was determined by the structural parameters of one-dimensional photonic crystal such as period, the position and width of bandgap and defect mode. The highest electric field intensity at defect layer is obtained with the alternated quarter-wavelength dielectric thin films of high and low refractive indexes and a defect mode matched with incident light wavelength..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1121 (2005)
Physical Optics
Research of Magnetic Granular Film Faraday Rotation Angle
[in Chinese], and [in Chinese]
Under an applied magnetic field, the Faraday magnetic-optical effect of composite media is dependent on the calculation of dielectric tensor. It is rather complicated to evaluate the dielectric tensor of composite media. Using the inhomogeneous composite effective electric field equal to the average electrie field the Under an applied magnetic field, the Faraday magnetic-optical effect of composite media is dependent on the calculation of dielectric tensor. It is rather complicated to evaluate the dielectric tensor of composite media. Using the inhomogeneous composite effective electric field equal to the average electrie field the effective-medium approximation equations of the inhomogeneous composite are derived. By use of dielectric tensor εe equation and self-consistency condition, the grain films systematic formula of magnetic-optical Faraday rotation angle is calculated. Corresponding matrix, ion concentration and the shape of metallic granular in grain films with Cu as example, the influence for magnetic granular films Faraday rotation angle is discussed. The effective medium approximate calculation is consistent with experimental result..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1126 (2005)
Quantum Optics
Cavity-Field Spectrum of Two Nonidentical Atoms Interacting with Single-Mode Quantized Radiation Field
[in Chinese], [in Chinese], and [in Chinese]
The cavity field spectrum of a pair of two-level atoms interacting with single-mode field with different coupling constants is studied. The new properties of the spectrum structure are discussed when the fields are initially in various number states. It is found that the shifts of peak-positions are symmetrical with thThe cavity field spectrum of a pair of two-level atoms interacting with single-mode field with different coupling constants is studied. The new properties of the spectrum structure are discussed when the fields are initially in various number states. It is found that the shifts of peak-positions are symmetrical with the increase of R from 0 to 1. With the increase of R, the number of the Rabi peaks changes according to 2→6→4 when the field is vacuum initially; and the peak number changes according to 2→6→12→9→7 for weak initial fields; the peak number changes according to 2→8→11→5 for strong fields. The peak-height changes rapid when the increase of R is from 0 to 0.3 for vacuum field, from 0 to 0.5 for weak field, and from 0 to 0.1 for strong field. When the photon-number of the initial field is vary large, the peak number changes according to 3→5→3 with the increase of R. The total height of the peaks increases monotonously with R changing from 0 to 1. The cooperative effect of atoms was shown..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1131 (2005)
Quantum Fluctuation of the Nonlinear Degenerate Optical Parametric Amplification
[in Chinese], and [in Chinese]
When pump depletion is considered, the analytical solution of Fokker-Planck equation of the nonlinear time-dependent degenerate optical parametric amplification (DOPA) in the P representation for generation of squeezed light is calculated. And then, the quantum fluctuation near or far away from threshold is evaluated. When pump depletion is considered, the analytical solution of Fokker-Planck equation of the nonlinear time-dependent degenerate optical parametric amplification (DOPA) in the P representation for generation of squeezed light is calculated. And then, the quantum fluctuation near or far away from threshold is evaluated. If the term (∝η) is neglected, the ordinary solution transits to the previous obtained linear approximate solution naturally. When considering the term (∝η), the solution and the perturbation series expansion theory of Drummond et al.. near threshold are coincided and adapted, while the perturbation series expansion theory far away from threshold is not adapted. The solution can apply to the whole region near or far away from threshold. When μ→0, quantum fluctuation is close to vacuum fluctuation; while μ1, the squeezing is near to the linear theory 1/1+μ..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1136 (2005)
Thin Films
Theoretical Research of Effect of Crystal Membranous Layer on Light Transmission of Polarizing Prism
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
For meeting rigor demands of modern light communication technology on each technic target of polarizer, a mathematically analytical expression of polarizing prism is deduced by means of theory of membranous layer when incident light is vertical to the crystal plane. Each physical parameter of affecting polarizing prismFor meeting rigor demands of modern light communication technology on each technic target of polarizer, a mathematically analytical expression of polarizing prism is deduced by means of theory of membranous layer when incident light is vertical to the crystal plane. Each physical parameter of affecting polarizing prism transmission technic target is analysed quantitatively. Computer simulations show that influential range of crystal thickness on transmission of polarizing prism associates with transmission of air inter layer. When parameters, such as crystal refractive index etc. are endowed with given values, for thickness of air inter layer h=26.2 μm and 27.4 μm, influential ranges of crystal thickness on transmission of Glan-Taylor prism are 5.934% and 7.034% respectively, and influential ranges of crystal thickness on transmission of Glan-Foucaul prism are 1.24% and 8.893%. Transmission of polarizing prism is affected by crystal thickness, air inter layer thickness and configuration angle. This theoretical research overcomes the shortcoming of previously transmission formulas of polarizing prism. They cannot analyse influence of crystal thickness on light transmission of polarizing prism quantitatively. The theory has importantly applied worthiness to polarimeter' design..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1143 (2005)
X-Ray Optics
A Point Spread Function Model for X-Ray Imaging
[in Chinese], [in Chinese], and [in Chinese]
The functioning of an X-ray imaging system is well characterized by its point spread function (PSF). The point spread function consists of prime point spread function and scatter point spread function. A point spread function model is developed for X-ray imaging system. Parameters in the model include part thickness, sThe functioning of an X-ray imaging system is well characterized by its point spread function (PSF). The point spread function consists of prime point spread function and scatter point spread function. A point spread function model is developed for X-ray imaging system. Parameters in the model include part thickness, source to detector distance and geometric parameters. Based on the model, an analytical expression for the scatter fraction is derived and it is a function of part thickness and source to detector distance. Experiment result proves correctness of the model by comparing calculated scatter fraction and the one measured from experiment. The model gives an estimation of scatter and geometric blur for their removal and is an effective model for X-ray imaging..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 25, Issue 8, 1148 (2005)
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