Journals >Chinese Optics Letters
Contents
2006
Volume: 4 Issue 4
20 Article(s)
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Fiber Optics and Optical Communications
Performance evaluation of modulation formats in 40*40-Gb/s WDM repeaterless transmission systems
Guangshan Lu, Kun Xu, Jian Wu, and Jintong Lin
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 accumTransmission 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04199 (2006)
PMD compensation based on a new type dynamic first-order PMD compensator
Jiajun Wang, Shilong Pan, Jia Jia, Yanfu Yang, and Caiyun Lou
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 compensatioA 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04202 (2006)
All-optical wavelength conversion based on nonlinear polarization rotation (NPR) in SOA and AWG filtering
Junyi Zhang, Jian Wu, Kun Xu, and Jintong Lin
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 twoAn 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04205 (2006)
Image Processing
Motion estimation based on an improved block matching technique
Tangfei Tao, Chongzhao Han, Yanqi Wu, and Xin Kang
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 betwAn 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04208 (2006)
Lasers and Laser Optics
Threshold gain behavior of lasing modes in two-dimensional active random media
Chun Wang, Jinsong Liu, Kejia Wang, Jiantao Lv, Ting Fan, and Hai Liu
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 threshThe 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04215 (2006)
Comparison of laser performance of electro-optic Q-switched Nd:YAG ceramic/single crystal laser
Jianghua Ji, Xiaolei Zhu, Chunyu Wang, Yongwei Feng, and Qihong Lou
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-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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04219 (2006)
Ultra-short pulsed ytterbium-doped fiber laser and amplifier
Guanglei Ding, Xin Zhao, Yishan Wang, Wei Zhao, and Guofu Chen
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 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04222 (2006)
Femtosecond laser ablation of Au film around single pulse threshold
Xiaochang Ni, Ching-Yue Wang, Yinzhong Wu, Li Yang, Wei Jia, and Lu Chai
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. FroAblation 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04225 (2006)
Er3+/Yb3+ codoped phosphate glass laser end-pumped by laser diode
Shilong Zhao, Shunguang Li, Lili Hu, and Zaixuan Zhang
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 tAn 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04228 (2006)
Materials
Negative refraction and reflection of Gaussian beam on two-dimensional photonic crystal slab
Yuntuan Fang, Yuzhen Liu, and Tinggen Shen
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 negaThe 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04230 (2006)
Nonlinear Optics
A tunable optical parametric generator by using a quasi-phase-matched crystal with different wedge angles
Tieli Zhang, Baigang Zhang, Haifeng Li, Feng Ji, Yang Lu, Xin Zhao, Peng Wang, and Jianquan Yao
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 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04234 (2006)
Thin Films
ZrO2 films with variable refractive index by glancing angle deposition
Xiaoyong Fu, Sumei Wang, Degang Deng, Kui Yi, Jianda Shao, and Zhengxiu Fan
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 degrWhen 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04247 (2006)
Coherence and Statistical Optics
Invariance of spectrum and polarization of electromagnetic Gaussian Schell-model beams propagating in free space
Jixiong Pu
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 poThe 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04196 (2006)
Quantum Optics
Manipulation role of the relative phase and incoherent pumping on a light pulse propagation
Ni Cui, Aiyun Li, Hui Ma, Hua Li, and Xijun Fan
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 fiIn 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04240 (2006)
Atomic and Molecular Physics
Size dependence of the maximum energy of protons from Coulomb explosion of methane clusters under intense femtosecond laser irradiation
Li Zheng, Cheng Wang, Shaohui Li, Bingchen Liu, Guoquan Ni, Ruxin Li, and Zhizhan Xu
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 (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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04189 (2006)
Total cross sections for electrons scattering from C2F4 and SO2 at 30-5000 eV: considering the geometric shielding effect
Deheng Shi, Jinfeng Sun, Yufang Liu, Zunlue Zhu, and Xiangdong Yang
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 moleculConsidering 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04192 (2006)
Instrumentation, Measurement, and Metrology
Stitching algorithm for annular subaperture interferometry
Xi Hou, Fan Wu, Li Yang, Shibin Wu, and Qiang Chen
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 annulaAnnular 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04211 (2006)
Optical Design and Fabrication
Analysis of illumination pupil filling ellipticity for critical dimensions control in photolithography
Liping Guo, Xiangzhao Wang, and Huijie Huang
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 unShrinking 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04237 (2006)
Spectroscopy
Mixture gas component concentration analysis based on support vector machine and infrared spectrum
Peng Bai, and Junhua Liu
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 daA 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%..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04243 (2006)
Atmospheric and Oceanic Optics
Iterative blind deconvolution of adaptive optics images
Ying Liang, Changhui Rao, Mei Li, and Zexun Geng
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 objAdaptive 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..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 4, 04187 (2006)
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