Journals >Chinese Optics Letters
Contents
2003
Volume: 1 Issue 12
15 Article(s)
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Image Processing
Speckle suppressing based on morphological filter and fuzzy logic
Lihui Jiang, Deming Ren, and Xuhu Lu
A novel morphological filtering algorithm is proposed for suppressing speckle noise in images. The algorithm employs directional morphological close-open and open-close operations, then computing the membership of the filtered versions’ every pixel according to the designed fuzzy rule. The final filtered image is compoA novel morphological filtering algorithm is proposed for suppressing speckle noise in images. The algorithm employs directional morphological close-open and open-close operations, then computing the membership of the filtered versions’ every pixel according to the designed fuzzy rule. The final filtered image is composed of all the pixels with corresponding maximal membership. The validity of the algorithm is demonstrated..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12689 (2003)
Lasers and Laser Optics
Stable mode-locking in an Yb:YAG laser with a fast SESAM
Guifang Ju, Lu Chai, Qingyue Wang, Zhigang Zhang, Yonggang Wang, and Xiaoyu Ma
Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor saturable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz.Stable mode-locking in a diode-pumped Yb:YAG laser was obtained with a very fast semiconductor saturable absorber mirror (SESAM). The pulse width was measured to be 4 ps at the central wavelength of 1047 nm. The average power was 200 mW and the repetition rate was 200 MHz..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12695 (2003)
A passively Q-switched diode pumped Yb:YAG microchip laser
Haisheng Wu, Ping Yan, Mali Gong, and Qiang Liu
A passively Q-switched diode pumped Yb:YAG microchip laser with Cr^(4+):YAG saturable absorber mirror is reported. The TEM00 laser pulses are obtained with 1.7-μJ pulse energy, 15-ns pulse width, 0.11-kW peak power, and a repetition rate of 2.2 kHz at 1049 nm. The doped concentration and dimension of Yb:YAG microchip cA passively Q-switched diode pumped Yb:YAG microchip laser with Cr^(4+):YAG saturable absorber mirror is reported. The TEM00 laser pulses are obtained with 1.7-μJ pulse energy, 15-ns pulse width, 0.11-kW peak power, and a repetition rate of 2.2 kHz at 1049 nm. The doped concentration and dimension of Yb:YAG microchip crystal are 10 at.-% and Ф5 × 0.6 mm^(2), respectively..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12697 (2003)
Materials
New chemically stable Er^(3+)-Yb^(3+) co-doped phosphate glass for optical waveguide lasers and amplifiers
Baoyu Chen, Shilong Zhao, and Lili Hu
A set of phosphate glasses with different amounts of Al_(2)O_(3), Na_(2)O, La_(2)O_(3) and AlF_(3) contents were prepared to search for a phosphate glass which is suitable for ion-exchange process. Based on chemical durability test results and spectroscopic properties, a glass with excellent chemical durability and gooA set of phosphate glasses with different amounts of Al_(2)O_(3), Na_(2)O, La_(2)O_(3) and AlF_(3) contents were prepared to search for a phosphate glass which is suitable for ion-exchange process. Based on chemical durability test results and spectroscopic properties, a glass with excellent chemical durability and good spectroscopic properties is developed for ion-exchange process. The emission cross section of Er^(3+) in this glass is calculated to be 0.72×10^(-20) cm^(2) by McCumber theory. The planar waveguide with three modes at 632.8 nm and one mode at 1540 nm can be realized by 335 ℃ 3 hours ion-exchange in 5%AgNO_(3)+95%KNO_(3) molten salt..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12699 (2003)
Influence of OH groups on 1.5-μm emission of Yb^(3+)/Er^(3+) co-doped tungsten-tellurite glasses
Jiacheng Li, Hefang Hu, and Fuxi Gan
The Yb^(3+)/Er^(3+) co-doped TeO_(2)-WO_(3)-ZnO glasses bubbling with different times were prepared. The infrared (IR) transmission spectra, emission spectra and fluorescence lifetime of Er^(3+) at 1.5μm were measured. The quench effects of OH groups on emission intensity of Er^(3+) at 1.5 μm as well as the relationshiThe Yb^(3+)/Er^(3+) co-doped TeO_(2)-WO_(3)-ZnO glasses bubbling with different times were prepared. The infrared (IR) transmission spectra, emission spectra and fluorescence lifetime of Er^(3+) at 1.5μm were measured. The quench effects of OH groups on emission intensity of Er^(3+) at 1.5 μm as well as the relationships between fluorescence decay rate and OH group content were investigated. The constant k_(OH-Er), which represents the strength of the interactions between Er^(3+) ions and OH groups, is approximately 17.0×10^(-20) cm^(4)/s, and is comparable to that for Er^(3+) in Yb^(3+)/Er^(3+) co-doped phosphate glasses..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12702 (2003)
Nonlinear Optics
Edge enhancement by using two-wave mixing and its application to pattern recognition
Huayong Ge, Qiushi Ren, Baohua Wang, Wanrong Li, and Haiying Cheng
Coupling theory is employed to analyze coupling gain and a new optical system is proposed for image edge enhancement, in which the ordinarily discarded background light is recycled as a pump source to amplify the signal light. We demonstrate the principle of optical correlation and compare the discrimination capabilityCoupling theory is employed to analyze coupling gain and a new optical system is proposed for image edge enhancement, in which the ordinarily discarded background light is recycled as a pump source to amplify the signal light. We demonstrate the principle of optical correlation and compare the discrimination capability of two kinds of correlators by computer simulation. The results show that edge enhancement preprocessing can improve discrimination capability effectively..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12705 (2003)
Performance curves comparison of THG efficiency in CsLiB_(6)O_(10) on flattened Gaussian and Gaussian beams
Li Wang, and Jianhua Xue
The conversion efficiency of THG on the flattened Gaussian and Gaussian beams is obtained in detail numerical stimulation for CsLiB_(6)O_(10). The conversion efficiencies of 86.7% and 96% of the flattened Gaussian are larger than those of Gaussian beams of 72.6% and 88% under type I and type II(1) phase matching. The eThe conversion efficiency of THG on the flattened Gaussian and Gaussian beams is obtained in detail numerical stimulation for CsLiB_(6)O_(10). The conversion efficiencies of 86.7% and 96% of the flattened Gaussian are larger than those of Gaussian beams of 72.6% and 88% under type I and type II(1) phase matching. The efficiencies affected by the pump intensity, polarization rate, crystal lengths and orders of the flattened Gaussian beams were presented..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12708 (2003)
Infrared OPO temperature tuning based on periodically-poled lithium niobate
Xuejin Li, Baigang Zhang, Jianquan Yao, and Jiefeng Zhang
An optical parametric oscillator (OPO) based on periodically-poled lithium niobate (PPLN) and pumped by 1064.2-nm laser is demonstrated, which can be conveniently tuned by the means of changing its operating temperature. The parameters of the set-up and experimental results are introduced in this paper. We adjusted theAn optical parametric oscillator (OPO) based on periodically-poled lithium niobate (PPLN) and pumped by 1064.2-nm laser is demonstrated, which can be conveniently tuned by the means of changing its operating temperature. The parameters of the set-up and experimental results are introduced in this paper. We adjusted the operating temperature from 80 to 250 ℃, the output wavelength shifted from 1485.4 to 1540.7 nm. The average of the shifts is 0.33 nm/℃..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12711 (2003)
Application of plasma shutter in second harmonic generation of AgGaSe_(2) crystal
Jinzhe Huang, Xiaoyong Hu, Deming Ren, and Yanchen Qu 1
A reliable target-triggering plasma shutter was applied to second harmonic generation (SHG) of AgGaSe_(2) crystal with a TEA CO_(2) laser. Under normal air pressure, argon charged plasma shutter was triggered by focusing beam companying with a pair of adjustable metal targets. Conversion efficiency was enhanced by 3.3 A reliable target-triggering plasma shutter was applied to second harmonic generation (SHG) of AgGaSe_(2) crystal with a TEA CO_(2) laser. Under normal air pressure, argon charged plasma shutter was triggered by focusing beam companying with a pair of adjustable metal targets. Conversion efficiency was enhanced by 3.3 times and the maximal efficiency 9.3%, with 1.4-mJ second harmonic energy was obtained. Finally, crystal damage was discussed together with previous work..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12714 (2003)
Optical Devices
Two-dimensional near-infrared photonic crystal fabrication by generation of void channels in solid resin
Guangyong Zhou, Michael James Ventura, and Min Gu
Two-dimensional (2D) triangular void channel photonic crystals with different lattice constants stacked in two different directions were fabricated by using femtosecond laser micro-explosion in solid polymer material. Fundamental and higher-order stop gaps were observed both in the infrared transmission and reflection Two-dimensional (2D) triangular void channel photonic crystals with different lattice constants stacked in two different directions were fabricated by using femtosecond laser micro-explosion in solid polymer material. Fundamental and higher-order stop gaps were observed both in the infrared transmission and reflection spectra. There is an approximately linear relationship between the gap position and the lattice constant. The suppression of the fundamental gap is as high as 70% for 24-layer structures stacked in the Γ-M direction..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12719 (2003)
Atomic and Molecular Physics
A scheme for the generation of two-mode atomic laser
Chunjia Huang, Ming Zhou, and Kewei Mo
The quantum dynamic behavior of the system composed of V-type three-level atomic Bose-Einstein condensate (BEC) interacting with two-mode coherent light field has been studied. The results show that the atoms of V-type three-level atomic BEC, which are excited to higher-level states under the action of light field, stiThe quantum dynamic behavior of the system composed of V-type three-level atomic Bose-Einstein condensate (BEC) interacting with two-mode coherent light field has been studied. The results show that the atoms of V-type three-level atomic BEC, which are excited to higher-level states under the action of light field, still keep their properties of coherent states. It demonstrates theoretically that two-mode atomic laser may be prepared by V-type three-level atomic BEC..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12686 (2003)
Instrumentation, Measurement, and Metrology
Research on direction recognizing and subdividing method for moire (interference) fringes
Xingchun Chu, Haibao Lu, and Juliang Cao
A new direction recognizing and subdividing method for moire (interference) fringes is presented. By setting two certain thresholds, counting errors caused by direct voltage excursion are avoided. Counting and direction recognizing are discussed in detail. Experimental results are given. The better adaptability and larA new direction recognizing and subdividing method for moire (interference) fringes is presented. By setting two certain thresholds, counting errors caused by direct voltage excursion are avoided. Counting and direction recognizing are discussed in detail. Experimental results are given. The better adaptability and large subdivision number are the good quality of this method..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12692 (2003)
OPTICAL DATA STORAGE
Thermal phase change and activation energy of crystallization of Ge-Sb-Te-Sn thin films
Sipeng Gu, Lisong Hou, Qitao Zhao, and Rui’an Huang
To improve the optical storage performance, Sn was doped into Ge_(2)Sb_(2)Te_(5) phase change thin films. The optical and thermal properties of Sn-doped Ge_(2)Sb_(2)Te_(5) film were investigated. The crystal structures of the as-sputtered and the annealed films were identified by the X-ray diffraction (XRD) method. TheTo improve the optical storage performance, Sn was doped into Ge_(2)Sb_(2)Te_(5) phase change thin films. The optical and thermal properties of Sn-doped Ge_(2)Sb_(2)Te_(5) film were investigated. The crystal structures of the as-sputtered and the annealed films were identified by the X-ray diffraction (XRD) method. The differential scanning calorimeter (DSC) method is used to get the crystallization temperature and crystallization energy (Ea). It was found that proper Sn-doping could highly improve storage performance of the Ge_(2)Sb_(2)Te_(5) media..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12716 (2003)
Atmospheric and Oceanic Optics
Compensating laser wave-front aberration in atmosphere 1.27 km away with SBS
Youlun Ju, Qi Wang, Deying Chen, Xin Yu, and Yuezhu Wang
It is reported that the wave-front aberration produced by atmosphere disturbance can be compensated with nonlinear optics phase conjugate technology. The distance of laser propagating in atmosphere is up to 1.27 km away. The result shows that SBS phase conjugating beam energy can be focus in a little area on target. AnIt is reported that the wave-front aberration produced by atmosphere disturbance can be compensated with nonlinear optics phase conjugate technology. The distance of laser propagating in atmosphere is up to 1.27 km away. The result shows that SBS phase conjugating beam energy can be focus in a little area on target. And the biggest energy of phase conjugating beam on target is up to 142 mJ..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12683 (2003)
Remote Sensing
Noise reduction in LOS wind velocity of Doppler lidar using discrete wavelet analysis
Songhua Wu, Zhishen Liu, and Dapeng Sun
The line of sight (LOS) wind velocity can be determined from the incoherent Doppler lidar backscattering signals. Noise and interference in the measurement greatly degrade the inversion accuracy. In this paper, we apply the discrete wavelet denoising method by using biorthogonal wavelets and adopt a distancedependent tThe line of sight (LOS) wind velocity can be determined from the incoherent Doppler lidar backscattering signals. Noise and interference in the measurement greatly degrade the inversion accuracy. In this paper, we apply the discrete wavelet denoising method by using biorthogonal wavelets and adopt a distancedependent thresholds algorithm to improve the accuracy of wind velocity measurement by incoherent Doppler lidar. The noisy simulation data are processed and compared with the true LOS wind velocity. The results are compared by the evaluation of both the standard deviation and correlation coefficient.The results suggest that wavelet denoising with distance-dependent thresholds can considerably reduce the noise and interfering turbulence for wind lidar measurement..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 1, Issue 12, 12722 (2003)
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