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Chinese Optics Letters 第4卷 第4期

Author Affiliations
Abstract
1 Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209
2 Graduate School of Chinese Academy of Sciences, Beijing 100039
3 People's Liberation Army Information Engineering University, Zhengzhou 450052
Adaptive optics (AO) technique has been extensively used for large ground-based optical telescopes to overcome the effect of atmospheric turbulence. But the correction is often partial. An iterative blind deconvolution (IBD) algorithm based on maximum-likelihood (ML) method is proposed to restore the details of the object image corrected by AO. IBD algorithm and the procedure are briefly introduced and the experiment results are presented. The results show that IBD algorithm is efficient for the restoration of some useful high-frequency of the image.
010.1080 Adaptive optics 100.0100 Image processing 100.1830 Deconvolution 
Chinese Optics Letters
2006, 4(4): 04187
Author Affiliations
Abstract
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
An investigation of the cluster size dependence of the maximum energy of protons ejected from explosion of methane clusters in an intense femtosecond laser field has been conducted on the basis of the cluster size estimation by Rayleigh scattering measurements. The interaction of a 2*10^(16)-W/cm2 intense laser pulse (790 nm, 60 fs) with the methane clusters revealed that the clusters were Coulomb exploded and the maximum energy (E_(max)) of the protons produced was linearly proportional to the square of the cluster radius (r_(c)^(2)). In a cluster size range, with the methane cluster radii up to about 3 nm, the established relation of E_(max) and r_(c)^(2) was found to be E_(max) (keV) = 3.3+0.75r_(c)^(2) (nm2), in good agreement with the simulation results. This demonstrated that Coulomb explosion of ionic clusters (C^(+4)H^(+)_(4))_(n) took place following the cluster vertical ionization in the laser-cluster interaction.
020.2070 Effects of collisions 320.2250 Femtosecond phenomena 350.5400 Plasmas 
Chinese Optics Letters
2006, 4(4): 04189
Author Affiliations
Abstract
1 College of Physics &
2 Electronic Engineering, Xinyang Normal University, Xinyang 464000
Considering the changes of the geometric shielding effect in a molecule as the incident electron energy varing, an empirical fraction, which is dependent on the incident electron energy, is presented. Using this empirical fraction, the total cross sections (TCSs) for electrons scattering from complex polyatomic molecules C2F4 and SO2 are calculated over a wide energy range from 30 to 5000 eV together with the additivity rule model at Hartree-Fock level. In the TCS calculations, the atoms are presented by the spherical complex optical potential, which is composed of static, exchange, polarization and absorption contributions. The quantitative TCSs above 100 eV are in good agreement with those obtained by experiments and other theories. It is proved that the empirical fraction, which exhibits the TCS contributions of shielded atoms in a molecule at different energies, is reasonable.
020.2070 Effects of collisions 020.0020 Atomic and molecular physics 
Chinese Optics Letters
2006, 4(4): 04192
Jixiong Pu 1,2,*
Author Affiliations
Abstract
1 Department of Electronic Science &
2 Technology, Huaqiao University, Quanzhou 362021
The propagation of polychromatic electromagnetic Gaussian Schell-model (EGSM) beams in free space is investigated. It is shown that the spectral degree of polarization, spectral degree of coherence, and normalized spectrum change generally on propagation. The conditions of keeping the spectral invariance and keeping polarization invariance for the polychromatic EGSM beams are derived respectively. The results indicate that the constraints on the parameters of EGSM source to keep polarization invariance on propagation are more rigorous than those to keep invariance of the normalized spectrum.
030.1640 Coherence 260.5430 Polarization 300.6170 Spectra 
Chinese Optics Letters
2006, 4(4): 04196
Author Affiliations
Abstract
Key Laboratory of Optical Communication and Lightwave Technologies, Ministry of Education, Beijing University of Posts and Telecommunications, Beijing 100876
Transmission performance of six modulation formats is numerically compared in 40*40-Gb/s wavelength division multiplexing (WDM) repeaterless systems. The results indicate that return-to-zero differential phase shift keying (RZ-DPSK) (33% duty cycle) demonstrates the best performance among all the formats when the accumulated amplified spontaneous emission power (AASEP) is small. But with the increasing of AASEP, the superiority of RZ-DPSK transmission performance over the other five modulation formats is vanished. AASEP is justified to be the major source for the deterioration of the superiority.
060.0060 Fiber optics and optical communications 060.4080 Modulation 120.4820 Optical systems 
Chinese Optics Letters
2006, 4(4): 04199
Author Affiliations
Abstract
Department of Electronic Engineering, Tsinghua University, Beijing 100084
A dynamic first-order polarization mode dispersion (PMD) compensator based on garnet and yttrium vanadate crystal has been proposed and implemented. Consisting of a differential group delay (DGD) generator and a Faraday rotator (FR), this PMD compensator has only two degrees of freedom. Feedback control and compensation algorithm are both very simple. Experimental results reveal the compensator behaviors to be excellent for PMD compensation in 40-Gb/s optical time domain multiplexing (OTDM) system.
060.2330 Fiber optics communications 230.5440 Polarization-sensitive devices 
Chinese Optics Letters
2006, 4(4): 04202
Author Affiliations
Abstract
Key Laboratory of Optical Communication and Lightwave Technologies, Ministry of Education, Beijing University of Posts and Telecommunications, Beijing 100876
An all-optical wavelength converter, based on nonlinear polarization rotation (NPR) in semiconductor optical amplifier (SOA) and array waveguide grating (AWG) filtering, is experimentally demonstrated. The wavelength converter can provide excellent operation including extinction ratio and Q factor. The simultaneous two wavelength conversion outputs are successfully obtained at 20 Gb/s.
060.4510 Optical communications 230.1150 All-optical devices 
Chinese Optics Letters
2006, 4(4): 04205
Author Affiliations
Abstract
1 Institute of Synthetic Automation, School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an 710049
2 Key Laboratory of Education Ministry for Modern Design and Rotor-Bearing System, Xi'an Jiaotong University, Xi'an 710049
An improved block-matching algorithm for fast motion estimation is proposed. The matching criterion is the sum of absolute difference. The basic idea is to obtain the best estimation of motion vectors by an optimization of the search process which can terminate the time-consuming computation of matching evaluation between the current block and the ineligible candidate block as early as possible and eliminate the search positions as many as possible in the search area. The performance of this algorithm is evaluated by theoretic analysis and compared with the full search algorithm (FSA). The simulation results demonstrate that the computation load of this algorithm is much less than that of FSA, and the motion vectors obtained by this algorithm are identical to those of FSA.
100.0100 Image processing 100.2000 Digital image processing 330.4150 Motion detection 
Chinese Optics Letters
2006, 4(4): 04208
Author Affiliations
Abstract
1 Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209
2 Graduate School of the Chinese Academy of Sciences, Beijing 100039
Annular subaperture interferometry (ASI) has been developed for low cost and flexible test of rotationally symmetric aspheric surfaces, in which accurately combining the subaperture measurement data corrupted by misalignments and noise into a complete surface figure is the key problem. By introducing the Zernike annular polynomials which are orthogonal over annulus, a method that eliminates the coupling problem in the earlier algorithm based on Zernike circle polynomials is proposed. Vector-matrix notation is used to simplify the description and calculations. The performance of this reduction method is evaluated by numerical simulation. The results prove this method with high precision and good anti-noise capability.
120.3940 Metrology 220.4840 Optical testing 070.4560 Optical data processing 000.3870 Mathematics 
Chinese Optics Letters
2006, 4(4): 04211
Author Affiliations
Abstract
State Key Laboratory of Laser Technology, Huazhong University of Science and Technology, Wuhan 430074
The pumping rate dependence of the peak intensity of the individual lasing mode in two-dimensional (2D) active random media is investigated. The results show that these modes have a typical threshold gain behavior and different threshold pumping rates. There exists a certain correspondence between the mode's threshold pumping rate and its lifetime, and the longer the lifetime is, the lower the threshold is.
290.0290 Scattering 290.4210 Multiple scattering 290.5850 Scattering, particles 290.5890 Scattering, stimulated 270.3430 Laser theory 
Chinese Optics Letters
2006, 4(4): 04215
Author Affiliations
Abstract
Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
An electro-optic Q-switched Nd:YAG ceramic laser operating at kHz repetition rate was demonstrated. Thermal induced lens' focus of ceramic rod was measured and compensated by plano-convex cavity structure. Depolarization loss at different output powers was measured in Nd:YAG single crystal and ceramic lasers. High-energy high-beam-quality laser pulse output was obtained in both laser structures. Pulse energy of about 20 mJ and pulse width of less than 12 ns were achieved, and the average power reached 20 W. The divergence of output laser beam was less than 1.2 mrad, and the beam propagation factor M2 was about 1.4.
140.3580 Lasers, solid-state 140.3540 Lasers, Q-switched 140.3480 Lasers, diode-pumped 
Chinese Optics Letters
2006, 4(4): 04219
Author Affiliations
Abstract
1 State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710068
2 Graduate School of the Chinese Academy of Sciences, Beijing 100039
This paper investigates a high power all fiber ultrashort pulse laser system. This system consists of a mode-locking laser oscillator, a multi-stage amplifier, a pulse selector, and a paired grating pulse compressor. With pulse energy of 12 uJ at repetition rate of 30 kHz, the laser at center wavelength of 1.05 um was obtained. Pulse width of 525 fs was achieved after the grating pair compressor.
060.2320 Fiber optics amplifiers and oscillators 140.3510 Lasers, fiber 140.7090 Ultrafast lasers 
Chinese Optics Letters
2006, 4(4): 04222
Author Affiliations
Abstract
1 Electronic Engineering Department, Tianjin University of Technology and Education, Tianjin 300222
2 Key Laboratory of Optoelectronic Information Technical Science, EMC
Ablation process of 1-kHz femtosecond lasers (pulse duration of 148 fs, wavelength of 775 nm) of Au film on silica substrates is studied. The thresholds for single and multi pulses can be obtained directly from the relation between the squared diameter D2 of the ablated craters and the laser fluence 'phi'0. From the plot of the accumulated laser fluence N'phi'_(th)(N) and the number of laser pulses N, incubation coefficient of Au film is obtained to be 0.765. Some experimental data obtained around the single pulse threshold are in good agreement with the theoretical calculation.
140.3330 Laser damage 160.3380 Laser materials 310.3840 Materials and process characterization 260.3910 Metals, optics of 
Chinese Optics Letters
2006, 4(4): 04225
Author Affiliations
Abstract
1 College of Information Engineering, China Jiliang University, Hangzhou 310018
2 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
An Er3+/Yb3+ phosphate laser glass was fabricated and characterized. According to McCumber theory, the stimulated emission cross-section of Er3+ ions at 1533 nm calculated by absorption spectrum was 0.84*10^(-20) cm2, and the fluorescence lifetime of 4I_(13/2) level was 8.5 ms. Continuous wave (CW) laser operation of this Er3+/Yb3+ phosphate glass pumped by laser diode (LD) was demonstrated at room temperature. The maximum output power of 80 mW and slope efficiency of 16.5% were obtained.
160.5690 Rare earth doped materials 300.6170 Spectra 140.3480 Lasers, diode-pumped 
Chinese Optics Letters
2006, 4(4): 04228
Author Affiliations
Abstract
1 Department of Physics, Zhenjiang Watercraft College, Zhenjiang 212003
2 Department of Physics, Nanjing University of Science and Technology, Nanjing 210094
3 Department of Physics, Jiangsu University, Zhenjiang 212003
The refraction and reflection of Gaussian beam on two-dimensional photonic crystal (2DPC) slab are studied by the finite-difference time-domain (FDTD) method. It is shown that 2DPC slab enables negative refraction, which is demystified by the distribution of Poynting vector directions and values inside the 2DPC. A negative Goos-Hanchen shift is also found in the simulation.
160.4670 Optical materials 350.5500 Propagation 120.5710 Refraction 
Chinese Optics Letters
2006, 4(4): 04230
Tieli Zhang 1,2,3,*Baigang Zhang 1,2,3Haifeng Li 1,2,3Feng Ji 1,2,3[ ... ]Jianquan Yao 1,2,3
Author Affiliations
Abstract
1 College of Precision Instrument and Opto-Electronics Engineering, Institute of Laser and Opto-Eletronics, Tianjin University, Tianjin 300072
2 Cooperated Institute of Nankai University and Tianjin University, Tianjin 300072
3 Key Laboratory of Opto-Electric Information Science and Technology (Ministry of Education), Tianjin University, Tianjin 300072
We report a tunable quasi-phase-matched optical parametric generator (OPG) with different wedge angles, pumped by a commercially available Q-switched diode-pumped Nd:YVO4 laser with a repetition of 50 kHz. The nonlinear crystal is a periodically poled MgO-doped LiNbO3 (PPMgOLN) with a period of 30 um. A congruent bulk LiNbO3 (LN) with three different wedge angles of 0, 4, and 9 deg. is placed in front of PPMgOLN. Rapid tuning has been achieved by simply moving the LN crystal along its lateral direction and over 60-mW average signal output power was obtained in the whole wavelength tuning range of 1539-1570 nm.
190.2620 Frequency conversion 190.4410 Nonlinear optics, parametric processes 190.4970 Parametric oscillators and amplifiers 
Chinese Optics Letters
2006, 4(4): 04234
Author Affiliations
Abstract
1 Information Optics Laboratory, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
2 Graduate School of the Chinese Academy of Sciences, Beijing 100039
Shrinking of critical dimensions (CDs) in semiconductor circuits has been pushing optical lithography to print features smaller than the wavelength of light source. The demand for CD control is ever-increasing. In this paper, the study is conducted to reveal the impact of illumination pupil filling ellipticity on CD uniformity. As main parameters of CD uniformity, horizontal-vertical feature bias (H-V bias) and isolated-dense feature bias (I-D bias) caused by pupil filling ellipticity are calculated using the PROLITH software under four different illumination settings. Simulation shows that H-V bias and I-D bias are proportional to the pupil filling ellipticity. The slopes of the fitting lines of the H-V bias versus pupil filling ellipticity are calculated.
220.0220 Optical design and fabrication 220.3740 Lithography 
Chinese Optics Letters
2006, 4(4): 04237
Author Affiliations
Abstract
College of Physics and Electronics, Shandong Normal University, Ji'nan 250014
In an open /\ type system with the spontaneously generated coherence (SGC), when the probe and driving fields have different frequencies, the switching of the group velocity of the probe pulse from subluminal to superluminal is realized not only by adjusting values of the relative phase between the probe and driving fields but also by varying values of the incoherent pumping rate. For the subluminal propagation, the system always exhibits the probe absorption, however, the superluminal propagation is always companied with gain of the probe field.
270.1670 Coherent optical effects 270.5530 Pulse propagation and solitons 
Chinese Optics Letters
2006, 4(4): 04240
Author Affiliations
Abstract
1 School of Electrical Engineering, Xi'an Jiaotong University, Xi'an 710049
2 Institute of Science, Air Force Engineering University, Xi'an 710051
A novel quantitative analysis method of multi-component mixture gas concentration based on support vector machine (SVM) and spectroscopy is proposed. Through transformation of the kernel function, the seriously overlapped and nonlinear spectrum data are transformed in high-dimensional space, but the high-dimensional data can be processed in the original space. Some factors, such as kernel function, range of the wavelength, and penalty coefficient, are discussed. This method is applied to the quantitative analysis of natural gas components concentration, and the component concentration maximal deviation is 2.28%.
300.6340 Spectroscopy, infrared 200.4740 Optical processing 070.4790 Optical spectrum analysis 
Chinese Optics Letters
2006, 4(4): 04243
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
2 Graduate School of the Chinese Academy of Sciences, Beijing 100039
When optical film is deposited at oblique angle incidences, the film becomes porously, and the film effective refractive index will decrease. Six porous ZrO2 films are fabricated by the glancing angle deposition (GLAD) technique with the different incidence angles. By changing the substrate tilt angle from 0 to 85 degrees, the film refractive index varies from 1.92 to 1.27.
240.0310 Thin films 310.6860 Thin films, optical properties 310.1860 Deposition and fabrication 
Chinese Optics Letters
2006, 4(4): 04247