Journals >Chinese Optics Letters
Contents
2007
Volume: 5 Issue 4
19 Article(s)
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Research Article
Ab initio configuration interaction study of the ground and low-lying excited states of ZnCd
Feng Gao, Chuanlu Yang, and Yongmian Dong
The multi-reference configuration interaction (MRCI) electronic energy calculations have been carried out on the ground state (X1'Sigma') as well as three low-lying excited states (3'Sigma', 1'Pi', 3'Pi') of ZnCd dimer. Potential energy curves (PECs) are therefore generated and fitted toThe multi-reference configuration interaction (MRCI) electronic energy calculations have been carried out on the ground state (X1'Sigma') as well as three low-lying excited states (3'Sigma', 1'Pi', 3'Pi') of ZnCd dimer. Potential energy curves (PECs) are therefore generated and fitted to the analytical potential energy functions (APEFs) using the Murrel-Sorbie (MS) potential function. Based on the PECs, the vibrational levels of each state are determined by solving Schrodinger equation of nuclear motion, and corresponding spectroscopic parameters are accurately calculated using the APEFs. The present values of spectroscopic parameters including equilibrium positions and dissociation energies are compared with other theoretical reports available at present..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 187 (2007)
Femtosecond laser induced index and relief gratings in polymer films
Yi Dong, Xiaoqiang Yu, Yuming Sun, Yufei Li, Xueyuan Hou, and Xian Zhang
A true single-step process suitable for fabrication of micro-periodic structure in polymer films by two-photon initiated photopolymerization and laser ablation is presented. By the right choice of the irradiation energy, the irradiated zone is modified or ablated in the 1.44-micron-thick film. The mechanism of grating A true single-step process suitable for fabrication of micro-periodic structure in polymer films by two-photon initiated photopolymerization and laser ablation is presented. By the right choice of the irradiation energy, the irradiated zone is modified or ablated in the 1.44-micron-thick film. The mechanism of grating generation and the potential application of the gratings in integrated optics are discussed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 191 (2007)
Guiding mode in elliptical core microstructured polymer optical fiber
Yani Zhang, Liyong Ren, Kang Li, Hanyi Wang, Wei Zhao, Lili Wang, Runcai Miao, Maryanne C. J. Large, and Martijn A. van Eijkelenborg
A kind of microstructured polymer optical fiber with elliptical core has been fabricated by adopting in-situ chemical polymerization technology and the secondary sleeving draw-stretching technique. Microscope photography demonstrates the clear hole-structure retained in the fiber. Though the holes distortion is visibleA kind of microstructured polymer optical fiber with elliptical core has been fabricated by adopting in-situ chemical polymerization technology and the secondary sleeving draw-stretching technique. Microscope photography demonstrates the clear hole-structure retained in the fiber. Though the holes distortion is visible, initial laser experiment indicates that light can be strongly confined in the elliptical core region, and the mode field is split obviously and presents the multi-mode characteristic. Numerical modeling is carried out for the real fiber with the measured parameters, including the external diameter of 150 microns, the average holes diameter of 3.3 microns, and the average hole spacing of 6.3 microns by using full-vector plane wave method. The guided mode fields of the numerical simulation are consistent with the experiment result. This fiber shows the strong multi-mode and weak birefringence in the visible and near-infrared band, and has possibility for achieving the fiber mode convertors, mode selective couplers and so on..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 194 (2007)
Diversity reception and equalization techniques for laser communication in space
Bo Liang, and Weibiao Chen
The principle of band-limited space optical communication system using the techniques of space diversity methods and time domain Rake receiver is analyzed. The joint channel equalizer method combining diversity reception and equalization technique is presented in space laser communication. By computer simulation, the bThe principle of band-limited space optical communication system using the techniques of space diversity methods and time domain Rake receiver is analyzed. The joint channel equalizer method combining diversity reception and equalization technique is presented in space laser communication. By computer simulation, the bit error rates of noncoherent space optical on-off keying signal using different space diversity methods, Rake reception with different inter-symbol interferences, joint diversity equalizations with different signal noise rates and different channel numbers are analysed. The results identify that joint diversity equalization method can enhance space optical communication performance evidently..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 197 (2007)
Restoration of solar and star images with phase diversity-based blind deconvolution
Qiang Li, Sheng Liao, Honggang Wei, and Mangzuo Shen
The images recorded by a ground-based telescope are often degraded by atmospheric turbulence and the aberration of the optical system. Phase diversity-based blind deconvolution is an effective post-processing method that can be used to overcome the turbulence-induced degradation. The method uses an ensemble of short-exThe images recorded by a ground-based telescope are often degraded by atmospheric turbulence and the aberration of the optical system. Phase diversity-based blind deconvolution is an effective post-processing method that can be used to overcome the turbulence-induced degradation. The method uses an ensemble of short-exposure images obtained simultaneously from multiple cameras to jointly estimate the object and the wavefront distribution on pupil. Based on signal estimation theory and optimization theory, we derive the cost function and solve the large-scale optimization problem using a limited memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) method. We apply the method to the turbulence-degraded images generated with computer, the solar images acquired with the swedish vacuum solar telescope (SVST, 0.475 m) in La Palma and the star images collected with 1.2-m telescope in Yunnan Observatory. In order to avoid edge effect in the restoration of the solar images, a modified Hanning apodized window is adopted. The star image still can be restored when the defocus distance is measured inaccurately. The restored results demonstrate that the method is efficient for removing the effect of turbulence and reconstructing the point-like or extended objects..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 201 (2007)
Fast algebra algorithm of shape-from-shading with specular reflectance
Lei Yang, and Jiuqiang Han
Shape-from-shading (SFS) is to reconstruct three-dimensional (3D) shape from a single gray image, which is an important problem in computer vision. We propose a novel SFS method based on hybrid reflection model which contains both diffuse reflectance and specular reflectance. The intensity gradient of image is in the dShape-from-shading (SFS) is to reconstruct three-dimensional (3D) shape from a single gray image, which is an important problem in computer vision. We propose a novel SFS method based on hybrid reflection model which contains both diffuse reflectance and specular reflectance. The intensity gradient of image is in the direction that the shape of surface changes most, so we use directional derivative of the reflectance map as parts of objective function. When discrete characteristic of digital images is considered, finite difference approximates differential operator. So the reflectance map equation described by a partial differential equation (PDE) turns into an algebra equation about the unknown surface height correspondingly. Using iterative numeric computation, a new SFS method is gained. Experiments on synthesis and real images show that the proposed SFS method is accurate and fast..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 204 (2007)
Measuring of the maximum measurable velocity for dual-frequency laser interferometer
Zhiping Zhang, Zhaogu Cheng, Zhaoyu Qin, and Jianqiang Zhu
There is an increasing demand on the measurable velocity of laser interferometer in manufacturing technologies. The maximum measurable velocity is limited by frequency difference of laser source, optical configuration, and electronics bandwidth. An experimental setup based on free falling movement has been demonstratedThere is an increasing demand on the measurable velocity of laser interferometer in manufacturing technologies. The maximum measurable velocity is limited by frequency difference of laser source, optical configuration, and electronics bandwidth. An experimental setup based on free falling movement has been demonstrated to measure the maximum measurable velocity for interferometers. Measurement results show that the maximum measurable velocity is less than its theoretical value. Moreover, the effect of kinds of factors upon the measurement results is analyzed, and the results can offer a reference for industrial applications..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 208 (2007)
Real-time displacement measurement with large range and high accuracy using sinusoidal phase modulating laser diode interferometer
Guotian He, Xiangzhao Wang, Aijun Zeng, Feng Tang, and Bingjie Huang
To resolve the conflict of large measurement range and high accuracy in the existing real-time laser diode (LD) interferometers for displacement measurement, a novel real-time LD interferometry for displacement measurement is proposed and its measurement principle is analyzed. By use of a new phase demodulation algoritTo resolve the conflict of large measurement range and high accuracy in the existing real-time laser diode (LD) interferometers for displacement measurement, a novel real-time LD interferometry for displacement measurement is proposed and its measurement principle is analyzed. By use of a new phase demodulation algorithm and a new phase compensation algorithm of real-time phase unwrapping, the measurement accuracy is improved, and the measurement range is enlarged to a few wavelengths. In experiments, the peak-to-peak amplitude of the speaker vibration was 2361.7 nm, and the repeatability was 2.56 nm. The measurement time was less than 26 microseconds..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 211 (2007)
Paired interference 3-dB coupler based on SOI rib waveguides with anisotropic chemical wet etching
Zhiyong Li, Jinzhong Yu, Shaowu Chen, Jingwei Liu, and Jinsong Xia
A 3-dB paired interference (PI) optical coupler in silicon-on-insulator (SOI) based on rib waveguides with trapezoidal cross section was designed with simulation by a modified finite-difference beam propagation method (FD-BPM) and fabricated by potassium hydroxide (KOH) anisotropic chemical wet etching. Theoretically, A 3-dB paired interference (PI) optical coupler in silicon-on-insulator (SOI) based on rib waveguides with trapezoidal cross section was designed with simulation by a modified finite-difference beam propagation method (FD-BPM) and fabricated by potassium hydroxide (KOH) anisotropic chemical wet etching. Theoretically, tolerances of width, length, and port distance are more than 1, 100, and 1 microns, respectively. Smooth interface was obtained with the propagation loss of 1.1 dB/cm at the wavelength of 1.55 microns. The coupler has a good uniformity of 0.2 dB and low excess loss of less than 2 dB..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 215 (2007)
Novel discretely tunable narrow linewidth fiber laser with uniform wavelength spacing
Xiaopeng Dong, and Yong Chen
A novel configuration of the tunable fiber laser with uniform wavelength spacing in dense wavelength division multiplexing (DWDM) application is proposed. The ring type tunable fiber laser consists of an all-fiber comb filter which determines the wavelength spacing, and a piece of adjustable fiber grating to select theA novel configuration of the tunable fiber laser with uniform wavelength spacing in dense wavelength division multiplexing (DWDM) application is proposed. The ring type tunable fiber laser consists of an all-fiber comb filter which determines the wavelength spacing, and a piece of adjustable fiber grating to select the discrete lasing wavelength for DWDM application. The proposed all-fiber ring type tunable laser has potential application in the DWDM and other optical systems due to its advantages such as narrow linewidth, easy tuning, uniform wavelength interval, etc...
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 218 (2007)
High power low-order modes operation of a multimode fiber laser
Libo Li, Qihong Lou, Jun Zhou, Jingxing Dong, Yunrong Wei, and Jinyan Li
Coiling technique is used to suppress high-order modes of a large mode area (LMA) double clad multimode fiber. Output powers and beam quality factors M2 are measured under two different coiling radii. 217 W with M2 of 2.96 can be obtained for coiling radius of 165 mm and 160 W with M2 of 1.38 for 52 mm. The correspondiCoiling technique is used to suppress high-order modes of a large mode area (LMA) double clad multimode fiber. Output powers and beam quality factors M2 are measured under two different coiling radii. 217 W with M2 of 2.96 can be obtained for coiling radius of 165 mm and 160 W with M2 of 1.38 for 52 mm. The corresponding slope efficiencies are 60% and 48%. With smaller coiling radius, the brightness is 3.4 times as high as that of the larger one..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 221 (2007)
Energy reduction: a technique for seed-injection locking of single-axial-mode Q-switched Nd:YAG laser
Sui Chen, Wenxiong Lin, Fei Shi, Jianhong Huang, Jinhui Li, Hui Zheng, Jipeng Lin, and Canhua Xu
A new technique for seed-injection locking of single-axial-mode (SAM) Q-switched Nd:YAG laser is reported. The technique called energy reduction (ER) is utilized when SAM operation is locked to design its feedback scheme. This method ensures long-term 100% seed-injection locking performance and the pulsed SAM output enA new technique for seed-injection locking of single-axial-mode (SAM) Q-switched Nd:YAG laser is reported. The technique called energy reduction (ER) is utilized when SAM operation is locked to design its feedback scheme. This method ensures long-term 100% seed-injection locking performance and the pulsed SAM output energy can reach as high as 200 mJ. Both temporal and spatial interferometric experiments have been executed to confirm the SAM oscillation..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 223 (2007)
2277-W continuous-wave diode-pumped heat capacity laser
Xiaodong Yang, Yong Bo, Qinjun Peng, Qianjin Cui, Aicong Geng, Dafu Cui, and Zuyan Xu
A high power continuous-wave (CW) diode-pumped Nd:YAG laser operated in heat capacity mode is demonstrated by use of two identical highly efficient diode-pumped laser heads placed in a plane-plane resonator. The laser heads are uniformly pumped with a five-fold symmetrical side-pumping configuration, and each head is aA high power continuous-wave (CW) diode-pumped Nd:YAG laser operated in heat capacity mode is demonstrated by use of two identical highly efficient diode-pumped laser heads placed in a plane-plane resonator. The laser heads are uniformly pumped with a five-fold symmetrical side-pumping configuration, and each head is able to output maximum output power of 2200 W at 808 nm. Under a total pump power of 4290 W, the output power of the laser at 1064 nm is up to 2277 W, corresponding to an optical-to-optical efficiency of 53.1%..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 226 (2007)
Er-doped fiber ring laser gyroscopes operating in continuous waves
Jingren Qian, Jue Su, Xuxu Wang, and Bing Zhu
A direction related polarizer was inserted into a ring laser cavity to eliminate one of the two eigen-modes as well as spatial hole burning of the gain medium in a bidirectional Er-doped fiber ring laser. Thus, a fiber ring laser gyroscope (FRLG) operating in continuous wave was demonstrated. A beat signal of over 30-dA direction related polarizer was inserted into a ring laser cavity to eliminate one of the two eigen-modes as well as spatial hole burning of the gain medium in a bidirectional Er-doped fiber ring laser. Thus, a fiber ring laser gyroscope (FRLG) operating in continuous wave was demonstrated. A beat signal of over 30-dB noise was observed and a good linear relation between the beat frequency shift and cavity rotation rate was obtained..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 229 (2007)
Accurate measurement of the main refractive indices and thermo-optical coefficients of the calcite crystal
Shuang Zhao, Fuquan Wu, Haifeng Wang, Weigang Zhong, Xiuzhen Li, Hengjing Tang, Meng Shi, and Hongyan Deng
The main refractive indices of calcite crystal are measured by the means of auto-collimation, and the thermo-optical coefficients are calculated. The coefficient expression of Sellmeier equation is obtained by solving Sellmeier equation strictly and the refractive indices of different wavelengths are calculated, which The main refractive indices of calcite crystal are measured by the means of auto-collimation, and the thermo-optical coefficients are calculated. The coefficient expression of Sellmeier equation is obtained by solving Sellmeier equation strictly and the refractive indices of different wavelengths are calculated, which accord with experimental results very well. The measured main refractive indices of calcite at 488-nm wavelength are identical with the values obtained by Sellmeier equation..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 232 (2007)
Wavelength dependence of soft tissue ablation by using pulsed lasers
Xianzeng Zhang, Shusen Xie, Qing Ye, and Zhenlin Zhan
Pulsed laser ablation of soft biological tissue was studied at 10.6-, 2.94-, and 2.08-micron wavelengths. The ablation effects were assessed by means of optical microscope, the ablation crater depths were measured with reading microscope. It was shown that Er:YAG laser produced the highest quality ablation with clear, Pulsed laser ablation of soft biological tissue was studied at 10.6-, 2.94-, and 2.08-micron wavelengths. The ablation effects were assessed by means of optical microscope, the ablation crater depths were measured with reading microscope. It was shown that Er:YAG laser produced the highest quality ablation with clear, sharp cuts following closely the spatial contour of the incident beam and the lowest fluence threshold. The pulsed CO2 laser presented the moderate quality ablation with the highest ablation efficiency. The craters drilled with Ho:YAG laser were generally larger than the incident laser beam spot, irregular in shape, and clearly dependent on the local morphology of biotissue. The ablation characteristics, including fluence threshold and ablation efficiency, varied substantially with wavelength. It is not evident that water is the only dominant chromophore in tissue..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 235 (2007)
A new Monte Carlo code for absorption simulation of laser-skin tissue interaction
Afshan Shirkavand, Saeed Sarkar, Marjaneh Hejazi, Leila Ataie-Fashtami, and Mohammad Reza Alinaghizadeh
In laser clinical applications, the process of photon absorption and thermal energy diffusion in the target tissue and its surrounding tissue during laser irradiation are crucial. Such information allows the selection of proper operating parameters such as laser power, and exposure time for optimal therapeutic. The MonIn laser clinical applications, the process of photon absorption and thermal energy diffusion in the target tissue and its surrounding tissue during laser irradiation are crucial. Such information allows the selection of proper operating parameters such as laser power, and exposure time for optimal therapeutic. The Monte Carlo method is a useful tool for studying laser-tissue interaction and simulation of energy absorption in tissue during laser irradiation. We use the principles of this technique and write a new code with MATLAB 6.5, and then validate it against Monte Carlo multi layer (MCML) code. The new code is proved to be with good accuracy. It can be used to calculate the total power absorbed in the region of interest. This can be combined for heat modelling with other computerized programs..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 238 (2007)
Problems on design of computer-generated holograms for testing aspheric surfaces: principle and calculation
Zhishan Gao, Meimei Kong, Rihong Zhu, and Lei Chen
Interferometric optical testing using computer-generated hologram (CGH) has provided an approach to highly accurate measurement of aspheric surfaces. While designing the CGH null correctors, we should make them with as small aperture and low spatial frequency as possible, and with no zero slope of phase except at centeInterferometric optical testing using computer-generated hologram (CGH) has provided an approach to highly accurate measurement of aspheric surfaces. While designing the CGH null correctors, we should make them with as small aperture and low spatial frequency as possible, and with no zero slope of phase except at center, for the sake of insuring low risk of substrate figure error and feasibility of fabrication. On the basis of classic optics, a set of equations for calculating the phase function of CGH are obtained. These equations lead us to find the dependence of the aperture and spatial frequency on the axial distance from the tested aspheric surface for the CGH. We also simulate the optical path difference error of the CGH relative to the accuracy of controlling laser spot during fabrication. Meanwhile, we discuss the constraints used to avoid zero slope of phase except at center and give a design result of the CGH for the tested aspheric surface. The results ensure the feasibility of designing a useful CGH to test aspheric surface fundamentally..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 241 (2007)
Influence of a high-speed dielectric spherical particle's movement on its scattering characteristics
Mingjun Wang, Zhensen Wu, and Yingle Li
The scattered field and differential scattered section (DSS) of a moving spherical particle with a high speed are investigated numerically. The coordinate and vector transformations are used to establish a theoretical basis for studying the laser scattering of a moving particle. The DSS of a moving spherical particle iThe scattered field and differential scattered section (DSS) of a moving spherical particle with a high speed are investigated numerically. The coordinate and vector transformations are used to establish a theoretical basis for studying the laser scattering of a moving particle. The DSS of a moving spherical particle is explained by the electric and magnetic field from Mie scattering theory. Assuming the laser wavelength of 1.06 microns, we compute the ratio of the laser DSS of the moving dielectric spherical particle to that of the static dielectric spherical particle, which changes with radii, speeds and scattering angles of the particle. The numerical results show that the laser DSS of the moving spherical particle is tightly connected with its speed and scattering zenith angle. If a spherical particle moves with high speed, the laser DSS due to movement of the particle could not be neglected. If the speed of the dielectric spherical particle is fluctuating, the Doppler effect and the frequency spectrum expansion play important roles..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 5, Issue 4, 245 (2007)
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