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2004
Volume: 2 Issue 7
20 Article(s)
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Diffraction and Gratings
Axial distribution of Gaussian beam limited by a hard-edged aperture
Shuyun Teng, Liren Liu, Zhu Luan, and Lingyu Wan
In this letter, the axial distribution of Gaussian beam limited by a hard-edged aperture is studied. We theoretically analyze the axial diffraction of Gaussian beam limited by a hard-edged aperture, and give the simpler formulas of the axial diffraction intensities of Gaussian beam in Fresnel diffraction field and FrauIn this letter, the axial distribution of Gaussian beam limited by a hard-edged aperture is studied. We theoretically analyze the axial diffraction of Gaussian beam limited by a hard-edged aperture, and give the simpler formulas of the axial diffraction intensities of Gaussian beam in Fresnel diffraction field and Fraunhofer diffraction field. The corresponding numerical calculation of axial diffraction intensity distribution of Gaussian beam with different wave waist is provided and the evolution of the diffraction distribution with the wave waist of Gaussian beam is explained. As the especial cases of the truncated Gaussian beam, the Gaussian beam in free space and the parallel light limited by the aperture are discussed too, and the system parameters of the truncated Gaussian beam which can cause it to equal to these cases are given. The theoretical results conform to the numerical analysis..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07376 (2004)
Fiber Optics and Optical Communications
Double-link failure protection algorithm for shared sub-path in survivable WDM mesh networks
Lei Guo, Hongfang Yu, and Lemin Li
We propose a novel shared sub-path protection (SSPP) algorithm to protect the double-link failures in wavelength division multiplexing (WDM) mesh networks. SSPP segments the primary path into several equal-length sub-paths and searches two link-disjoint backup paths for each sub-path. When computing the paths, SSPP conWe propose a novel shared sub-path protection (SSPP) algorithm to protect the double-link failures in wavelength division multiplexing (WDM) mesh networks. SSPP segments the primary path into several equal-length sub-paths and searches two link-disjoint backup paths for each sub-path. When computing the paths, SSPP considers the load balance and the resource sharing degree, so that the blocking ratio can be effectively reduced. The simulation results show that SSPP not only can completely protect the double-link failures but also can make the tradeoffs between the resource utilization ratio (or blocking ratio) and the protection-switching time..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07379 (2004)
Image Processing
Hepatic CT image query using Gabor features
Chenguang Zhao, Hongyan Cheng, and Tiange Zhuang
A retrieval scheme for liver computerize tomography (CT) images based on Gabor texture is presented. For each hepatic CT image, we manually delineate abnormal regions within liver area. Then, a continuous Gabor transform is utilized to analyze the texture of the pathology bearing region and extract the corresponding feA retrieval scheme for liver computerize tomography (CT) images based on Gabor texture is presented. For each hepatic CT image, we manually delineate abnormal regions within liver area. Then, a continuous Gabor transform is utilized to analyze the texture of the pathology bearing region and extract the corresponding feature vectors. For a given sample image, we compare its feature vector with those of other images. Similar images with the highest rank are retrieved. In experiments, 45 liver CT images are collected, and the effectiveness of Gabor texture for content based retrieval is verified..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07383 (2004)
Image fusion based on expectation maximization algorithm and steerable pyramid
Gang Liu, Zhongliang Jing, Shaoyuan Sun, Jianxun Li, Zhenhua Li, and Henry Leung
In this paper, a novel image fusion method based on the expectation maximization (EM) algorithm and steerable pyramid is proposed. The registered images are first decomposed by using steerable pyramid. The EM algorithm is used to fuse the image components in the low frequency band. The selection method involving the inIn this paper, a novel image fusion method based on the expectation maximization (EM) algorithm and steerable pyramid is proposed. The registered images are first decomposed by using steerable pyramid. The EM algorithm is used to fuse the image components in the low frequency band. The selection method involving the informative importance measure is applied to those in the high frequency band. The final fused image is then computed by taking the inverse transform on the composite coefficient representations. Experimental results show that the proposed method outperforms conventional image fusion methods..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07386 (2004)
A novel video object tracking approach using bidirectional projection
Zhi Liu, and Jie Yang
This paper proposes a novel video object tracking approach using birdirectional projection. Forward projection is exploited to locate the current video object with rough boundary information. Watershed segmentation is applied to the simplified gradient image of the current frame to obtain a reasonable partition. An impThis paper proposes a novel video object tracking approach using birdirectional projection. Forward projection is exploited to locate the current video object with rough boundary information. Watershed segmentation is applied to the simplified gradient image of the current frame to obtain a reasonable partition. An improved backward projection, which incorporates pixel classification with region classification, is performed on some segmented regions in a rather small search range, and the tracking performance is enhanced in respect to both reliability and efficiency. Experimental results for various types of the MPEG-4 (moving picture experts group) test sequences demonstrate an efficient and faithful segmentation performance of the proposed approach..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07390 (2004)
Lasers and Laser Optics
Generation of high energy and good beam quality pulses with a master oscillator power amplifier
Zhigang Li, Z. Xiong, Nicholas Moore, Chen Tao, G. C. Lim, Weiling Huang, and Dexiu Huang
A high efficiency and high peak power laser system with short-pulse and good beam quality has been demonstrated by using a master oscillator power amplifier with two-pass amplification configuration. The master oscillator, end-pumped with a fiber-coupled laser diode array, provides low power but excellent beam quality A high efficiency and high peak power laser system with short-pulse and good beam quality has been demonstrated by using a master oscillator power amplifier with two-pass amplification configuration. The master oscillator, end-pumped with a fiber-coupled laser diode array, provides low power but excellent beam quality pulses, and the amplifier boosts the pulse energy by orders without significant beam quality degradation. Short pulses of 8.5 ns with energy up to 130 mJ and approximatelydiffraction limited beam quality have been demonstrated..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07399 (2004)
Diode-pumped 1123-nm Nd:YAG laser
Xiaoping Guo, Meng Chen, Gang Li, Bingyuan Zhang, Jiandong Yang, Zhigang Zhang, and Yonggang Wang
We demonstrated a diode-pumped Nd:YAG laser with a plano-concave resonator. When the pump power is 1.57 W, the output power of 1123-nm laser is 132 mW at the temperature of 20 oC, and the power change is less than 2% in an hour. A periodicallypoled LiNbO3 (PPLN) was used as outer cavity frequency-doubling crystal and 5We demonstrated a diode-pumped Nd:YAG laser with a plano-concave resonator. When the pump power is 1.57 W, the output power of 1123-nm laser is 132 mW at the temperature of 20 oC, and the power change is less than 2% in an hour. A periodicallypoled LiNbO3 (PPLN) was used as outer cavity frequency-doubling crystal and 561-nm laser was observed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07402 (2004)
Diode-pumped vertical external cavity surface emitting laser at 1 um
Xiaoping Guo, Meng Chen, Gang Li, Yanrong Song, Bingyuan Zhang, and Zhigang Zhang
We demonstrated a diode-pumped vertical external cavity surface emitting laser with simple plane-concave cavity. When the pump power at a wavelength of 811.6 nm is 1.5 W, the maximum output power is 40.4 mW at the wavelength of 1005.8 nm. Theoptical-optical conversion efficiency is 2.7%.We demonstrated a diode-pumped vertical external cavity surface emitting laser with simple plane-concave cavity. When the pump power at a wavelength of 811.6 nm is 1.5 W, the maximum output power is 40.4 mW at the wavelength of 1005.8 nm. Theoptical-optical conversion efficiency is 2.7%..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07405 (2004)
Investigations and experiments of a new multi-layer complex liquid-cooled mirror
Yuling Lu, Zuhai Cheng, Yaoning Zhang, Feng Sun, and Wenfeng Yu
This paper describes a new multi-layer complex liquid-cooled Si mirror with 3 cooling ducts in Archimedes spirals. Utilizing the ANSYS program, the structure of the mirror is optimized and the thermal deformation model of the mirror is simulated. The simulation results show that the mirror has the following advantages:This paper describes a new multi-layer complex liquid-cooled Si mirror with 3 cooling ducts in Archimedes spirals. Utilizing the ANSYS program, the structure of the mirror is optimized and the thermal deformation model of the mirror is simulated. The simulation results show that the mirror has the following advantages: very small amount of surface deformation, uniform distribution of temperature and surface deformation, and fast surface shape restoration. The results of the experiments of thermal deformation and the surface restoration are accurately mapped to the simulation results..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07407 (2004)
Medical Optics and Biotechnology
Application of transcutaneous diffuse reflectance spectroscopy in the measurement of blood glucose concentration
Wenliang Chen, Rong Liu, Houxin Cui, Kexin Xu, and Lina Lv
In this paper, the propagation characteristics of near-infrared (NIR) light in the palm tissue are analyzed, and the principle and feasibility of using transcutaneous diffuse reflectance spectroscopy for non-invasive blood glucose detection are presented. An optical probe suitable for measuring the diffuse reflectance In this paper, the propagation characteristics of near-infrared (NIR) light in the palm tissue are analyzed, and the principle and feasibility of using transcutaneous diffuse reflectance spectroscopy for non-invasive blood glucose detection are presented. An optical probe suitable for measuring the diffuse reflectance spectrum of human palm and a non-invasive blood glucose detection system using NIR spectroscopy are designed. Based on this system, oral glucose tolerance tests are performed to measure the blood glucose concentrations of two young healthy volunteers. The partial least square calibration model is then constructed by all individual experimental data. The final result shows that correlation coefficients of the two experiments between the predicted blood glucose concentrations and the reference blood glucose concentrations are 0.9870 and 0.9854, respectively. The root mean square errors of prediction of full cross validation are 0.54 and 0.52 mmol/l, respectively..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07411 (2004)
Nonlinear Optics
Quasi-soliton generation in solid-state lasers with semiconductor saturable absorber
Palihati Mijeti, and Tursunjan Ablekim
Recent advances in ultrafast, ultra-short solid-state lasers have resulted in sub-6 fs pulses generated directly from the cavity of Ti:sapphire lasers. The generation of extremely short pulses is possible due to the formation of a quasi-Schrodinger soliton. Our investigation is directed to the peculiarities of the tranRecent advances in ultrafast, ultra-short solid-state lasers have resulted in sub-6 fs pulses generated directly from the cavity of Ti:sapphire lasers. The generation of extremely short pulses is possible due to the formation of a quasi-Schrodinger soliton. Our investigation is directed to the peculiarities of the transition between femtosecond to picosecond generation. We found that the above transition is accompanied by the threshold and hysteresis phenomena. On the basis of soliton perturbation theory, the numerical simulation studying two different experimental situations has been performed, the first situation corresponds to the study of the lasers field's parameters under variation of control parameters (dispersion or pump power), the second one is for continuous variation of control parameter within a single generation session. Physically it corresponds to not repeated laser session but the variation of control parameter when the pulse has formed already..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07414 (2004)
Continuous-wave four-wave mixing with linear growth based on electromagnetically dual induced transparency
Jiahua Li, Wenxing Yang, and Jucun Peng
Using Schrodinger-Maxwell formalism, we propose and analyze a continuous-wave four-wave mixing (FWM) scheme for the generation of coherent light in a six-level atomic system based on electromagnetically dual induced transparency. We derive the corresponding explicit analytical expressions for the generated mixing fieldUsing Schrodinger-Maxwell formalism, we propose and analyze a continuous-wave four-wave mixing (FWM) scheme for the generation of coherent light in a six-level atomic system based on electromagnetically dual induced transparency. We derive the corresponding explicit analytical expressions for the generated mixing field. We find that the scheme greatly enhances FWM production efficiency and is also capable of inhibiting and delaying the onset of the detrimental three-photon destructive interference by choosing the proper decay rate in the second electromagnetically induced transparency (EIT) process. In addition, such an optical process also provides possibilities for producing short-wave-length coherent radiation at low pump intensities..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07418 (2004)
Effect of focal pumping conditions on the phase-conjugation characteristics of STS and SBS
Anling Liu, Weijun Zhang, Xiaoming Gao, and Jun Qu
The phase-conjugation characteristics of stimulated thermal scattering (STS) in absorbing liquid and stimulated Brillouin scattering (SBS) separately excited in pure acetone were compared, and the effect of focal pumping conditions on them was studied. It is shown that high-quality phase conjugation can be obtained by The phase-conjugation characteristics of stimulated thermal scattering (STS) in absorbing liquid and stimulated Brillouin scattering (SBS) separately excited in pure acetone were compared, and the effect of focal pumping conditions on them was studied. It is shown that high-quality phase conjugation can be obtained by STS in absorbing liquid under stronger pumping conditions..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07421 (2004)
Optical Devices
Fabrication and characterization of two-dimensional pin-cushion position sensitive detectors
Dongyan Chen, Bin Lin, and Yuqing Chen
In this paper, the fabrication and testing results of a two-dimensional pin-cushion position sensitive detector (PSD) are presented. The obtained pin-cushion PSD with an 8 * 8 mm2 effective area presents a maximum spectral response of 0.5 mA/mW at 850-nm wavelength, a 12-nA dark current at 5-V reverse voltage, a reversIn this paper, the fabrication and testing results of a two-dimensional pin-cushion position sensitive detector (PSD) are presented. The obtained pin-cushion PSD with an 8 * 8 mm2 effective area presents a maximum spectral response of 0.5 mA/mW at 850-nm wavelength, a 12-nA dark current at 5-V reverse voltage, a reverse breakdown voltage of 50 V, a nonlinearity of 2.175%, and a spatial resolution of 10 um. The spatial resolution is relatively low and the slight pin-cushion concave distortion is generated due to the incompletely satisfied relationship between sheet resistivity of the anode and the resistance per unit length..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07426 (2004)
Physical Optics
Energy flow in negative index materials
Lorenzo Bolla, Michele Midrio, and Carlo G. Someda
From Maxwell's equations, we compute the speed and the direction of propagation of active power refracted from air into a negative index material. We prove, both analytically and numerically that the power may refract positively even if phase fronts refract negatively. Considerations on the usage of ray optics in pFrom Maxwell's equations, we compute the speed and the direction of propagation of active power refracted from air into a negative index material. We prove, both analytically and numerically that the power may refract positively even if phase fronts refract negatively. Considerations on the usage of ray optics in problems involving negative index materials are drawn..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07428 (2004)
Instrumentation, Measurement, and Metrology
Measuring vibration by using fiber Bragg grating and demodulating it by blazed grating
Xiaojin Guo, Zongmin Yin, and Ning Song
A method of measuring vibration by using fiber Bragg grating (FBG) and demodulating the spectrum by blazed grating is introduced. The sensor system is made of a simple supported beam with a FBG adhered to its upper surface. A blazed grating is used to demodulate the changing spectrum that is got from the sensor system,A method of measuring vibration by using fiber Bragg grating (FBG) and demodulating the spectrum by blazed grating is introduced. The sensor system is made of a simple supported beam with a FBG adhered to its upper surface. A blazed grating is used to demodulate the changing spectrum that is got from the sensor system, and a line charge-coupled device (CCD) is used to accept the diffraction spectrum. Through analyzing the number of the CCD's pixels, we can get the amplitude of vibration and the change of the temperature. The experimental results show that the vibration amplitude of the exciter matches the detected signal under the stable frequency. The temperature shift and vibration signal are also successfully separated..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07393 (2004)
A modified moire interferometer for three-dimensional displacement measurement
Weining Wang, and Jianhai Sun
This paper presents a new optical interferometric system, MMI-T/G, composed of a modified four-beam moire interferometer and a Twyman/Green interferometer. The MMI-T/G system can measure three-dimensional displacement fringe patterns with a single loading on the specimen, and the in-plane and out-of-plane displacement This paper presents a new optical interferometric system, MMI-T/G, composed of a modified four-beam moire interferometer and a Twyman/Green interferometer. The MMI-T/G system can measure three-dimensional displacement fringe patterns with a single loading on the specimen, and the in-plane and out-of-plane displacement fields can be measured independently and defined clearly. The optical setup has the advantages of structural novelty, flexibility, and high fringe contrast. Moreover, the in-plane displacement sensitivity is twice of that of the normal moire interferometer. The measuring techniques to obtain the fringe patterns and displacement fields using the MMI-T/G system are described. The experimental results of thermal displacement of an electronic device are shown..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07396 (2004)
OPTICAL DATA STORAGE
Three-dimensional optical data storage using a solid immersion lens to focus a femtosecond laser pulse
Fengtao He, Guanghua Cheng, Xiaoqiang Feng, Dongling Zhang, Zhao Cheng, Qing Liu, Wei Zhao, Guofu Chen, and Xun Hou
A solid immersion lens (SIL) has been applied to the writing and reading of three-dimensional optical data storage in transparent materials. Using a SIL with n=1.516 to focus a 150-fs, 800-nm Ti:sapphire laser, the 5-layer reading and writing of data are achieved in fused silica and polyethylene methacrylate at a densiA solid immersion lens (SIL) has been applied to the writing and reading of three-dimensional optical data storage in transparent materials. Using a SIL with n=1.516 to focus a 150-fs, 800-nm Ti:sapphire laser, the 5-layer reading and writing of data are achieved in fused silica and polyethylene methacrylate at a density of 1.1*10^(12) b/cm3. Some advantages of the employment of SIL have been discussed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07423 (2004)
Scattering
Study on the shadowing effect for optical wave scattering from randomly rough surface
Lixin Guo, Yunhua Wang, and Zhensen Wu
Based on the Kirchhoff approximation for rough surface scattering and by calculating the shadowing function of the rough surface, the formula of the scattering cross section of the dielectric rough surface is presented with consideration of the shadowing effect for the optical wave incidence. It is obtained that in comBased on the Kirchhoff approximation for rough surface scattering and by calculating the shadowing function of the rough surface, the formula of the scattering cross section of the dielectric rough surface is presented with consideration of the shadowing effect for the optical wave incidence. It is obtained that in comparison with the conventional Kirchhoff solution, the shadowing effect should not be neglected for the optical wave scattering from the rough surface. The influence of the shadowing effect for different incidence angle, surface root mean square slope, and surface roughness on the scatteringcross section is discussed in detail..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07431 (2004)
Atmospheric and Oceanic Optics
Aperture-averaging effects for weak to strong scintillations in turbulent atmosphere
Yixin Zhang, Tuo Zhu, and Chunkan Tao
Under the approximations of (1) the received irradiance fluctuations of an optical wave caused by small scale turbulent eddies are multiplicatively modulated by the fluctuations caused by large scale turbulent eddies; (2) the scintillations caused by small- and large-scale eddies, respectively, are statistically indepeUnder the approximations of (1) the received irradiance fluctuations of an optical wave caused by small scale turbulent eddies are multiplicatively modulated by the fluctuations caused by large scale turbulent eddies; (2) the scintillations caused by small- and large-scale eddies, respectively, are statistically independent; (3) the Rytov method for optical scintillation collected by the finite-diameter receiving aperture is valid for light wave propagation under weak to saturation fluctuation regime, we develop the applicable aperture-averaging analytic formulas in the week-to-strong-fluctuation for the scintillations of plane and spherical waves, which include the outer- and inner-scale rules of turbulence..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 2, Issue 7, 07373 (2004)
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