Contents
2002
Volume: 22 Issue 1
27 Article(s)
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Research Article
Soft X-Ray Contact Microscopy by an Atomic Force Microscope
Jiang Shiping, Zhang Yuxuan, Gao Hongyi, Chen Jianwen, Zhang Xinyi, and Xu Zhizhan
The instruments for reading relief in the photoresist related with the resolutions of soft X-ray contact microimaging are described. Comparing the micrographs made by an atomic force microscope with that by optical microscopes experimentally, the conclusion can be drawn that the atomic force microscope is a very good mThe instruments for reading relief in the photoresist related with the resolutions of soft X-ray contact microimaging are described. Comparing the micrographs made by an atomic force microscope with that by optical microscopes experimentally, the conclusion can be drawn that the atomic force microscope is a very good method for amplifying the images in the resists..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 118 (2002)
Atmospheric Optics and Oceanic Optics
Aperture Averaging of Saturated Scintillation of Laser Propagation in the Atmosphere
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The characteristics of the temporal spectrum of optical scintillation in a finite aperture in the turbulent atmosphere are analyzed theoretically. Experiments of laser scintillation in a pinhole and a 260 mm aperture were carried out along a 6.8 km propagation path. Comparisons of scintillation spectra and standard deThe characteristics of the temporal spectrum of optical scintillation in a finite aperture in the turbulent atmosphere are analyzed theoretically. Experiments of laser scintillation in a pinhole and a 260 mm aperture were carried out along a 6.8 km propagation path. Comparisons of scintillation spectra and standard deviations are made between those for the pinhole and the 260 mm aperture. It can be concluded that the aperture averaging can be saturation-resistant for the saturation to some extent. This provides a foundation for measuring optical turbulence intensity using scintillation in a finite aperture..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 36 (2002)
Fiber Optics and Optical Communications
Algebraic Recursion Formulas for Perturbation Calculation of Propagation Characteristics of Graded-Index Optical Waveguides
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Algebraic recursion formulas for perturbation calculation of successive order approximate propagation constants of graded-index profile planar optical waveguides are derived by the use of hypervirial theorem (HVT) and Hellmann-Feynman theorem (HFT) in quantum mechanics. Algebraic formulas for calculation of modal fieldAlgebraic recursion formulas for perturbation calculation of successive order approximate propagation constants of graded-index profile planar optical waveguides are derived by the use of hypervirial theorem (HVT) and Hellmann-Feynman theorem (HFT) in quantum mechanics. Algebraic formulas for calculation of modal field with given approximate value of propagation constant are also presented. Numerical results for several typical examples are given. The merit of the present method is that it can be applied to straightforward calculation of propagation constants and the corresponding modal fields in perturbation order..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 24 (2002)
Fourier Optics and Signal Processing
The Implementation of a Perfect Shuffle Type of Optoelectronic Neural Network System
[in Chinese], [in Chinese], and [in Chinese]
Based on the study of optical implementation of the perfect shuffle local interconnecting, a hybrid opto-electrical perfect shuffle type of neural network experiment system is constructed with full functions of weighted interconnecting and summing, nonlinear processing and feeding back. Optical associative recognizing Based on the study of optical implementation of the perfect shuffle local interconnecting, a hybrid opto-electrical perfect shuffle type of neural network experiment system is constructed with full functions of weighted interconnecting and summing, nonlinear processing and feeding back. Optical associative recognizing experiments for numeral patterns in 8×8 pixels are proceeded employing the PS-IPA algorithm. The experimental results show a good agreement with theoretical simulations and the feasibility and superiority of the shuffle network theory is then confirmed. And large-scale perfect shuffle type of practical ONNs with 10 4 neurons are expected utilizing smart pixel array device..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 62 (2002)
Instrumentation, Measurement and Metrology
Performance Comparison of Photon Counting Quadrant Tracking System and Intensifier CCD Tracking System
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on the basic principle of photon counting Quadrant tracking system and intensifier CCD tracking system, the measured noise error, the controlling characteristic and the closed-loop noise error of these two tracking systems are analyzed and compared. The experimental results are presented. The results show that thBased on the basic principle of photon counting Quadrant tracking system and intensifier CCD tracking system, the measured noise error, the controlling characteristic and the closed-loop noise error of these two tracking systems are analyzed and compared. The experimental results are presented. The results show that the performance of photon counting Quadrant tracking system is superior to that of intensifier CCD tracking system..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 67 (2002)
Lasers and Laser Optics
Analysis of Influence of Phase Conjugate Laser upon the Threshold of Optical Parametric Oscillator
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The threshold of singly resonant KTP (θ=90°,φ=0°) optical parametric oscillator was reduced significantly (about 50%) by use of stimulated brillouin scattering (SBS) phase-conjugate Nd∶YAG laser as a pumping source comparing with the use of conventional multimode pumping source. Theoretical analysis shows thaThe threshold of singly resonant KTP (θ=90°,φ=0°) optical parametric oscillator was reduced significantly (about 50%) by use of stimulated brillouin scattering (SBS) phase-conjugate Nd∶YAG laser as a pumping source comparing with the use of conventional multimode pumping source. Theoretical analysis shows that the OPO′s threshold energy fluence depends on the pulse width, non-symmetrical temporal profile (sharp leading edge), and beam mode structure. The compressed pulse-width, sharp leading edge and single spatial mode with good beam quality contribute to the OPO′s threshold reducing..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 45 (2002)
Passively Q-Switched Self-Frequency Doubling Nd3+:Ca4GdO(BO3)3 Laser with Cr4+:YAG Saturable Absorber
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Nd3+∶Ca4GdO(BO3)3, known as Nd∶GdCOB, is a new self-frequency doubling laser crystal. Using Cr 4+∶YAG as passive Q-switch, the Q-switched laser running at 0.53 μm with the Nd∶GdCOB crystal is realized. The pulse width, single pulse energy and repetition rate under different small-signal transmission of Cr 4+∶YAG and diNd3+∶Ca4GdO(BO3)3, known as Nd∶GdCOB, is a new self-frequency doubling laser crystal. Using Cr 4+∶YAG as passive Q-switch, the Q-switched laser running at 0.53 μm with the Nd∶GdCOB crystal is realized. The pulse width, single pulse energy and repetition rate under different small-signal transmission of Cr 4+∶YAG and different pump conditions are measured and the numerical solutions of the coupling wave rate equations agree with the experimental results..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 50 (2002)
Pulse Amplifying and Frequency Expanding of a Narrow Linewidth and Tunable Ti:Sapphire Laser
[in Chinese], [in Chinese], and [in Chinese]
A mathematical formulae for a sliced, amplified and frequency expanded Ti∶sapphire laser is setup and computed, by using optical parametric effect in time and frequency domain. Tunable and narrow linewidth (<0.02 nm) laser output with the frequency expansion of 120 nm (560 nm～680 nm) is obtained from Ti∶sapphire lasA mathematical formulae for a sliced, amplified and frequency expanded Ti∶sapphire laser is setup and computed, by using optical parametric effect in time and frequency domain. Tunable and narrow linewidth (<0.02 nm) laser output with the frequency expansion of 120 nm (560 nm～680 nm) is obtained from Ti∶sapphire laser using BBO-OPO in the experiment..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 54 (2002)
Comparative Laser Study of Nd:KGW and Nd:YAG Pumped by Flashlamp
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A comparative study of Nd∶KGW and Nd∶YAG laser crystals was conducted under the same experimental conditions in free-running mode and the Q-switched mode, which were pumped by flashlamp at a repetition rate of 1 Hz with a pulse duration of 120 μs. In free-running operation, the slope efficiencys and the extrapolated enA comparative study of Nd∶KGW and Nd∶YAG laser crystals was conducted under the same experimental conditions in free-running mode and the Q-switched mode, which were pumped by flashlamp at a repetition rate of 1 Hz with a pulse duration of 120 μs. In free-running operation, the slope efficiencys and the extrapolated energy thresholds were determined to be 1.0%,0.44% and 0.54 J, 0.76 J for Nd∶KGW and Nd∶YAG rods, respectively. The slope efficiency of 0.16% and 0.07% for the Nd∶KGW and the Nd∶YAG were obtained in Q-switched mode with the extrapolated energy threshold of 5.9 J and 12.5 J, respectively..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 58 (2002)
Materials
Growth of Cr,Ca:YAG by Liquid Phase Epitaxy
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The growth of saturable absorber Cr 4+∶YAG crystals by liquid phase epitaxy (LPE) is reported. The absorption characteristics of this co-doped Cr,Ca∶YAG epilayer is analyzed. The transmission variation ΔT (i.e. the difference between saturated and unsaturated transmissions at 1.06 μm) could be adjusted easily in a rangThe growth of saturable absorber Cr 4+∶YAG crystals by liquid phase epitaxy (LPE) is reported. The absorption characteristics of this co-doped Cr,Ca∶YAG epilayer is analyzed. The transmission variation ΔT (i.e. the difference between saturated and unsaturated transmissions at 1.06 μm) could be adjusted easily in a range of 5%～30% by adjusting the concentration of Cr and /or the thickness of the epilayer during LPE and or by polishing. It is believed that this Cr,Ca∶YAG epilayer is well qualified for the development of passively Q-switched monolithic microchip laser as a solid-state saturable absorber. It shows that there is also the existence of Cr5+ ion in this Cr,Ca:YAG epilayer..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 107 (2002)
Studies on Cr3+ Doped K2O-ZnO-Al2O3-B2O3-SiO2 Transparent Mullite Glass-Ceramics
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The crystallization and optical spectra of the Cr 3+ doped K 2O-ZnO-Al 2O 3-B 2O 3-SiO 2 glasses were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), absorption spectra and fluorescence spectra. The experimental results show that the addition of ZnO to the Cr 3+ doped K 2O-Al 2O 3-B 2O 3-SiOThe crystallization and optical spectra of the Cr 3+ doped K 2O-ZnO-Al 2O 3-B 2O 3-SiO 2 glasses were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), absorption spectra and fluorescence spectra. The experimental results show that the addition of ZnO to the Cr 3+ doped K 2O-Al 2O 3-B 2O 3-SiO 2 glass makes the crystallizability of glass improve obviously, the crystalline temperature decrease and the nanometre grade mullite micro-crystal more uniform and regular. As a result the luminescence of glass-ceramics is stronger..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 110 (2002)
Exciton Optical Properties of CdSe/CdZnSe Superlattices
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
CdSe/Cd 0.65Zn 0.35Se superlattices were grown by molecular beam epitaxy on substrate GaAs. The structure and exciton optical properties in high quality CdSe/CdZnSe superlattices are investigated by means of XRD spectra, photoluminescence spectra with different excitation power at 77 K and photoluminescence spectra witCdSe/Cd 0.65Zn 0.35Se superlattices were grown by molecular beam epitaxy on substrate GaAs. The structure and exciton optical properties in high quality CdSe/CdZnSe superlattices are investigated by means of XRD spectra, photoluminescence spectra with different excitation power at 77 K and photoluminescence spectra with different temperature. The emission peak from exciton-exciton scattering is observed in CdSe/CdZnSe superlattices. It is validated by photoluminescence spectra with different excitation power and different temperature. The linewidth of the exciton emission becomes broader with increasing temperature. The linewidth at low temperature is due to the alloy composition and well thickness fluctuations, and the linewidth broadening at high temperature is contributed by the interactions among the exciton and LO phonons and ionized donor impurities. The photoluminescence intensities are reduced with increasing temperature, which is mainly due to the thermal dissociation of excitons, i. e., the electrons or holes jump from the wells into the barriers by thermal excitations..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 114 (2002)
Nonlinear Optics
An Analytical Study on Cherenkov Cascading Second Order Nonlinearity
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The analytical study on the nonlinear phase shift and the change of fundamental wave amplitude caused by Cherenkov cascading second order nonlinearity is given. The result shows that a very large nonlinear phase shift (>π) could be attained by choosing an appropriate reversal period, and a rather large nonlinear phaThe analytical study on the nonlinear phase shift and the change of fundamental wave amplitude caused by Cherenkov cascading second order nonlinearity is given. The result shows that a very large nonlinear phase shift (>π) could be attained by choosing an appropriate reversal period, and a rather large nonlinear phase shift can be attained even if the waveguide does not modulated periodically. The Cherenkov configuration has many advantages such as the large fabrication tolerance, the natural separation of fundamental wave and the SHG wave etc, thus this configuration can be applied to the all-optical switches..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 6 (2002)
Third Harmonic Generation in Air Through Interaction with Ultrashort Intense Laser Pulses
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Generation of the third harmonic from the interaction between femtosecond intense laser pulses and atmosphere air is studied. The UV third harmonic with power as high as 0.17 GW and 10HZ repetition is obtained successfully. An efficiency of third-harmonic generation is up to 0.04%. The conversion efficiency and mode stGeneration of the third harmonic from the interaction between femtosecond intense laser pulses and atmosphere air is studied. The UV third harmonic with power as high as 0.17 GW and 10HZ repetition is obtained successfully. An efficiency of third-harmonic generation is up to 0.04%. The conversion efficiency and mode structure of the harmonics generated in free air and microcapillary are compared. The experimental results show that the conversion efficiency of THG is a little lower in capillary, but its radial profile is improved effectively which will benefit to practical application..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 10 (2002)
Second-Harmonic Generation of Phase Aberrated Laser Beams by Type ⅠPhase Matching in Uniaxial Crystals
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The second-harmonic generation theory of phase aberrated laser beam in uniaxial crystals is discussed, in cluding the effects of diffraction and transverse walkoff. The solutions of the undepleted-pump approximation is given. The conversion efficiency of Gauss beams with aberrations is calculated according to the solutThe second-harmonic generation theory of phase aberrated laser beam in uniaxial crystals is discussed, in cluding the effects of diffraction and transverse walkoff. The solutions of the undepleted-pump approximation is given. The conversion efficiency of Gauss beams with aberrations is calculated according to the solutions. The solution can be used under any assumptions of intensity distribution and phase aberration of the pumping wave..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 14 (2002)
A New Z-Scan Theory Based on Diffraction Model
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
Based on Fresnel-Kirchhoff diffraction theory, a diffraction model of nonlinear optical media to Gaussian beam is set up, which can explain the Z-scan phenomenon from a new way. This theory is not only well consistent with the conventional Z-scan theory in the case of smaller nonlinear phase shift, but also can fit forBased on Fresnel-Kirchhoff diffraction theory, a diffraction model of nonlinear optical media to Gaussian beam is set up, which can explain the Z-scan phenomenon from a new way. This theory is not only well consistent with the conventional Z-scan theory in the case of smaller nonlinear phase shift, but also can fit for the larger nonlinear phase shift. Numeric computations indicate the shape of the Z-scan curve is greatly affected by the value of the nonlinear phase shift. The symmetric dispersion-like Z-scan curve is only valid for small nonlinear phase shift (<π), but with increasing the nonlinear phase shift, the valley of the transmittance is severely suppressed and the peak is greatly enhanced. The laser power through the aperture will oscillate and attenuate as the nonlinear phase shift increases due to the increasing of the input laser power..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 19 (2002)
Optical Design and Fabrication
Genetic Algorithm Applied to Automatic Lens Design
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
An attempt is made to use the genetic algorithm (GA) in the field of lens design. Mathematical model is constructed, and program code developed. Experimental results show that GA can realize the automatic increase or decrease of optical surfaces in the lens system during the optimization process, which is an important An attempt is made to use the genetic algorithm (GA) in the field of lens design. Mathematical model is constructed, and program code developed. Experimental results show that GA can realize the automatic increase or decrease of optical surfaces in the lens system during the optimization process, which is an important step towards automatic design with artificial intelligence..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 74 (2002)
Optical Devices
Investigations on Multi-Layer Photonic-Crystal Optical-Filters
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A new optical-filter structure consisted of a number of pieces of 1-D photonic crystals, each of which with a different lattice constant, and its operation mechanism are presented. Numerical and experimental studies are performed and their results are in good accordance with each other. This structure can be applied toA new optical-filter structure consisted of a number of pieces of 1-D photonic crystals, each of which with a different lattice constant, and its operation mechanism are presented. Numerical and experimental studies are performed and their results are in good accordance with each other. This structure can be applied to build different kind of filters, such as low-pass filters, band-pass filters, narrow-band-pass filters and high-pass filters, etc. Extraordinary wide band-stop and extremely narrow band-pass filters can be easily realized with such a structure..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 79 (2002)
EFPI/FBG Strain-Temperature Sensor and Application
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
The structure and principle of a novel sensor with in-fibre Bragg grating (FBG) and extrinsic Fabry-Perot interferometer (EFPI) in series, used for simultaneous strain and temperature measurement, are presented. The cross-talk between the reflective spectra of the FBG and the EFPI interference spectra is observed whichThe structure and principle of a novel sensor with in-fibre Bragg grating (FBG) and extrinsic Fabry-Perot interferometer (EFPI) in series, used for simultaneous strain and temperature measurement, are presented. The cross-talk between the reflective spectra of the FBG and the EFPI interference spectra is observed which has been reduced by the method of averaging the wavelengths at the two points of 3 dB bandwidth to improve the accuracy for temperature measurement. This sensor has been applied to simultaneous strain and temperature measurement for 3-D braided composite materials. The experimental results show that this method has a strain accuracy of ±20 με and a temperature accuracy of 1 ℃, which can meet the requirements for practical applications..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 85 (2002)
A High-Sensitivity Fiber Grating Pressure Sensor and Its Pressure Sensing Characteristics
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
A high sensitivity fiber grating pressure sensor using the enhance-sensitivity-coated jar has been designed and studied. The pressure sensitivity is up to -5.277 nm/Mpa, which is corresponding to the sensitivity coefficients of -3.41×10 -3 Mpa -1. The sensitivity is about 1722 times the value of the bare fiber. ThA high sensitivity fiber grating pressure sensor using the enhance-sensitivity-coated jar has been designed and studied. The pressure sensitivity is up to -5.277 nm/Mpa, which is corresponding to the sensitivity coefficients of -3.41×10 -3 Mpa -1. The sensitivity is about 1722 times the value of the bare fiber. The linearity is very good. This kind of sensor has potential applications in the sensing measurement at low-pressure..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 89 (2002)
Design and Error Analysis of Trapeziform Grating for High Density Optical Disk Storage
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
For the purpose of design and fabrication, diffraction efficiencies of the trapeziform phase gratings are deduced and compared with rectangular gratings. The parameter design of the grating for high density optical disk storage are presented. Influences of fabrication errors including random errors and system errors arFor the purpose of design and fabrication, diffraction efficiencies of the trapeziform phase gratings are deduced and compared with rectangular gratings. The parameter design of the grating for high density optical disk storage are presented. Influences of fabrication errors including random errors and system errors are deduced and analyzed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 92 (2002)
Switching Characteristic of Semiconductor Optical Amplifier Based Demultiplexer with Symmetric Mach-Zehnder Interferometer Configuration
[in Chinese], and [in Chinese]
The switching characteristic of a semiconductor optical amplifier based demultiplexer with symmetric Mach-Zehnder Interferometer (SOA-MZI) operating at colliding pulse Mach-Zehnder (CPMZ) and travelling pulse Mach-Zehnder (TPMZ) configuration is analyzed. It shows that the control pulse width, the SOA length effect andThe switching characteristic of a semiconductor optical amplifier based demultiplexer with symmetric Mach-Zehnder Interferometer (SOA-MZI) operating at colliding pulse Mach-Zehnder (CPMZ) and travelling pulse Mach-Zehnder (TPMZ) configuration is analyzed. It shows that the control pulse width, the SOA length effect and the nonlinear gain compression effect influence the width of the switching window, and they are the main factors in limiting the switching speed of the CPMZ configuration. When the control pulse width is less than the SOA transition time, switching contrast ratio of CPMZ will begin to decrease if the delay between the two control pulses is less than the twice of SOA transition time. However when the control pulse width exceeds the SOA transition time, the switching contrast ratio will decrease even the delay is larger than the twice of SOA transition time. Hence a short control pulse and a delay larger than the twice of SOA transition time are required to enable the CPMZ to operate at a high speed with a high switching contrast ratio. While TPMZ configuration is almost free from the SOA′s length effect..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 99 (2002)
Physical Optics
Non-Relativistic Intense Laser Propagation Characteristics in the Plasmas
[in Chinese], [in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In the non-relativistic limits, long pulses and ultra-short pulses laser propagation characteristics in the fully-ionized plasma are discussed. The electron density distribution can be derived from the balance of the pondermotive force with the thermal force in long pulses and with the electrostatic force in ultra-shorIn the non-relativistic limits, long pulses and ultra-short pulses laser propagation characteristics in the fully-ionized plasma are discussed. The electron density distribution can be derived from the balance of the pondermotive force with the thermal force in long pulses and with the electrostatic force in ultra-short regime. Using the source-dependent expansion (SDE) method, the laser field propagation characteristics in plasma can be described through the numerical solution of the enveloped equation. In long pulses, the self-guiding, which means the laser spot size oscillates in the spread direction, will appear if the ratio of the laser power and the plasma temperature exceeds the threshold. The guiding cannel is steady in some initial laser spot size and the optimal condition to produce the narrowest steady channel is found. In ultra-short pulses, the effective Rayleigh length of laser increases but self-guiding does not occur according to the numerical solution and theoretic analysis..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 1 (2002)
Quantum Optics
Interfering Fringe of Resonant Fluorescence from Cold Atomic Cloud in a MOT and Its Applications
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
It is observed that the interfering fringe produced by two virtual images of cold in a magneto-optical trap (MOT) atom cloud presenting on a plane glass of a low-vapour-pressure cell. Using the fringe the number of trapped atoms are estimated. And from contrast of the fringe the information about density disturb of atoIt is observed that the interfering fringe produced by two virtual images of cold in a magneto-optical trap (MOT) atom cloud presenting on a plane glass of a low-vapour-pressure cell. Using the fringe the number of trapped atoms are estimated. And from contrast of the fringe the information about density disturb of atom cloud can be got..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 41 (2002)
Rapid Communications
Propagation Characteristics of Lightwave in Side-Polished Poled Fibers
[in Chinese], [in Chinese], [in Chinese], [in Chinese], and [in Chinese]
On the basis of configuration of side-polished poled fiber, a model of six-layer waveguide with double metal layers is put forwavd to describe the poled fiber and analyze the propagation characteristics of lightwave in the poled fibers. The analysis indicated that the lightwave propagating in the poled fiber has characOn the basis of configuration of side-polished poled fiber, a model of six-layer waveguide with double metal layers is put forwavd to describe the poled fiber and analyze the propagation characteristics of lightwave in the poled fibers. The analysis indicated that the lightwave propagating in the poled fiber has characteristics of polarization extinction due to the existence of metal electrodes deposited on the flat of the optical fiber. The main parameters of the device that affects the propagation characteristics of poled fiber are the distance between the core and polished flat, and the thickness of insulator adjacent to the anode..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 121 (2002)
Control of Unit Amplifier Gain in Built-up Double-Pass Coaxial Amplifiers
[in Chinese], [in Chinese], [in Chinese], and [in Chinese]
In accordance with the built-up structure of the main amplifier in "SHENGGUANG Ⅱ" laser system, a new scheme of using angular variable mirror (AVM) to control unit amplifier gain for power balance is proposed. The gain change of double-pass amplifier caused by the AVM attenuation is analysed.In accordance with the built-up structure of the main amplifier in "SHENGGUANG Ⅱ" laser system, a new scheme of using angular variable mirror (AVM) to control unit amplifier gain for power balance is proposed. The gain change of double-pass amplifier caused by the AVM attenuation is analysed..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 126 (2002)
Thin Films
Calculation and Analysis of Multilayers for Phase-Change Super-Resolution Optical Disks
[in Chinese], [in Chinese], and [in Chinese]
Ge-Sb-Te is a kind of phase-change optical recording material with good performance. It can be used as mask layer in the super-resolution optical disks. The relation of the multilayer′s optical parameters (reflectivity and reflectivity contrast) and the film thickness of the structure of the six layers of phase-change Ge-Sb-Te is a kind of phase-change optical recording material with good performance. It can be used as mask layer in the super-resolution optical disks. The relation of the multilayer′s optical parameters (reflectivity and reflectivity contrast) and the film thickness of the structure of the six layers of phase-change super-resolution optical disks are studied. The ideal result of thickness for each layer is given..
Acta Optica Sinica
- Publication Date: Jan. 01, 1900
- Vol. 22, Issue 1, 30 (2002)
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