Journals >Chinese Optics Letters
Contents
2006
Volume: 4 Issue 12
13 Article(s)
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Research Article
Two-dimensional novel optical lattices with multi-well traps for cold atoms or molecules
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We propose some new schemes to constitute two-dimensional (2D) array of multi-well optical dipole traps for cold atoms (or molecules) by using an optical system consisting of a binary 'pi'-phase grating and a 2D array of rectangle microlens. We calculate the intensity distribution of each optical well in 2D arrWe propose some new schemes to constitute two-dimensional (2D) array of multi-well optical dipole traps for cold atoms (or molecules) by using an optical system consisting of a binary 'pi'-phase grating and a 2D array of rectangle microlens. We calculate the intensity distribution of each optical well in 2D array of multi-well traps and its geometric parameters and so on. The proposed 2D array of multi-well traps can be used to form novel 2D optical lattices with cold atoms (or molecules), and form various novel optical crystals with cold atoms (or molecules), or to perform quantum computing and quantum information processing on an atom chip, even to realize an array of all-optical multi-well atomic (or molecular) Bose-Einstein condensates (BECs) on an all-optical integrated atom (or molecule) chip..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 683 (2006)
Improved silica fiber with enhanced ultraviolet transmission
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When a silica optical fiber is used for transmitting ultraviolet (UV) light, the problems associated with the damage and transmission deterioration of silica fiber in the UV region need to be solved in the fabrication process. In this paper, an improved silica fiber fabrication process was presented to enhance UV transWhen a silica optical fiber is used for transmitting ultraviolet (UV) light, the problems associated with the damage and transmission deterioration of silica fiber in the UV region need to be solved in the fabrication process. In this paper, an improved silica fiber fabrication process was presented to enhance UV transmission, which combined the UV pre-irradiation on high-OH concentration preform with heat treatment while drawing fiber. The impact of the structural defects and color centers was diminished greatly by the new method of fabrication. The experimental results accorded with the theoretical analysis, and transmission was improved about 0.4-0.7 dB/m for wavelength from 350 to 400 nm..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 687 (2006)
Optical power equalization using Fabry-Perot semiconductor optical amplifier
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A novel scheme of optical power equalization based on Fabry-Perot semiconductor optical amplifier (FP-SOA) is proposed. Because of the gain characteristic of FP-SOA, real-time controlling mechanism according to input optical power is aborted in the scheme. The simulations show that 10-dB pulse peak power variation can A novel scheme of optical power equalization based on Fabry-Perot semiconductor optical amplifier (FP-SOA) is proposed. Because of the gain characteristic of FP-SOA, real-time controlling mechanism according to input optical power is aborted in the scheme. The simulations show that 10-dB pulse peak power variation can be clamped in less than 1 dB. The influences of injecting current, pulse periods, and pulse width are discussed..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 690 (2006)
Denoising lidar signal by combining wavelet improved threshold with wavelet domain spatial filtering
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Lidar is an effective tool for remotely monitoring target or object, but the lidar signal is often affected by various noises or interferences. Therefore, detecting the weak signals buried in noises is a fundamental and important problem in the lidar systems. In this paper, an effective noise reduction method combiningLidar is an effective tool for remotely monitoring target or object, but the lidar signal is often affected by various noises or interferences. Therefore, detecting the weak signals buried in noises is a fundamental and important problem in the lidar systems. In this paper, an effective noise reduction method combining wavelet improved threshold with wavelet domain spatial filtration is presented to denoise pulse lidar signal and is investigated by detecting the simulating pulse lidar signals in noise. The simulation results show that this method can effectively identify the edge of signal and detect the weak lidar signal buried in noises..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 694 (2006)
Target detection under sea background using constructed biorthogonal wavelet
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A new technique is presented to detect targets under sea background. Focused on interested areas, the spatial and frequency distributions are first studied, then analytic expression of targets is set up by least square method (LSM). According to the shape, frequency, and analytic expression of targets, a matched biorthA new technique is presented to detect targets under sea background. Focused on interested areas, the spatial and frequency distributions are first studied, then analytic expression of targets is set up by least square method (LSM). According to the shape, frequency, and analytic expression of targets, a matched biorthogonal wavelet is constructed to better enhance targets and eliminate noises. Results show the usefulness of this method for single frame detection (signal to noise ratio SNR>=1.25), which provides a better performance than classic wavelets and morphological filtering..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 697 (2006)
Measuring normal spectral emissivities of niobium by a pulse-heating technique: 1000 K to the melting point
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The normal spectral emissivity of niobium strip specimen is measured using a new pulse-heating reflectometric technique. The hemispherical spectral reflectivity of the surface of a strip tangent to an integrating sphere is determined by a high-speed lock-in technique. At the same time, the radiance temperature of the sThe normal spectral emissivity of niobium strip specimen is measured using a new pulse-heating reflectometric technique. The hemispherical spectral reflectivity of the surface of a strip tangent to an integrating sphere is determined by a high-speed lock-in technique. At the same time, the radiance temperature of the strip is measured by the multi-wavelength high-speed pyrometer from approximately 1000 K to the melting point. Details of the measurement method and of the related calibration techniques are reported. Results of the normal spectral emissivity of niobium at 633, 753, 827, and 905 nm from room temperature to its melting point are presented. The accuracy of spectral emissivities is estimated better than 5%..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 701 (2006)
A spectroscopic method for determining thickness of quartz wave plate
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A spectroscopic method to determine thickness of quartz wave plate is presented. The method is based on chromatic polarization interferometry. With the polarization-resolved transmission spectrum (PRTS) curve, the phase retardation of quartz wave plate can be determined at a wide spectral range from 200 to 2000 nm obviA spectroscopic method to determine thickness of quartz wave plate is presented. The method is based on chromatic polarization interferometry. With the polarization-resolved transmission spectrum (PRTS) curve, the phase retardation of quartz wave plate can be determined at a wide spectral range from 200 to 2000 nm obviously. Through accurate judgment of extreme points of PRTS curve at long-wave band, the physical thickness of quartz wave plates can be obtained exactly. We give a measuring example and the error analysis. It is found that the measuring precision of thickness is mainly determined by the spectral resolution of spectrometer..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 705 (2006)
Simultaneous quantitative evaluation of in-plane and out-of-plane deformation by use of a carrier method of large image-shearing shearography
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A carrier method for separating out-of-plane displacement from in-plane components based on large image-shearing shearography is presented. A reference surface is fixed on the side of a test object. They are illuminated by two expanded symmetric illuminations respectively. The carrier is introduced by rotating the refeA carrier method for separating out-of-plane displacement from in-plane components based on large image-shearing shearography is presented. A reference surface is fixed on the side of a test object. They are illuminated by two expanded symmetric illuminations respectively. The carrier is introduced by rotating the reference surface to modulate the displacement of an object. By using Fourier transform to demodulate the modulated fringe pattern, two phase maps, which include out-of-plane and in-plane displacements, can be obtained. Then the out-of-plane displacement can be easily separated from in-plane displacement by subtraction and addition of the two unwrapped phase distributions. The principle of the method is presented and proved by a typical three-point-bending experiment. Experimental results show that the method enjoys high visibility of carrier fringes. The system does not need a special beam as a reference light and has simple optical setup..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 709 (2006)
New method for lightning location using optical ground wire
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A new technology of lightning location is described, which is based on detecting the state of polarization (SOP) fluctuation of the laser light in the optic ground wire (OPGW). Compared with the conventional lightning location method, the new method is more accurate, more stable, and cheaper. Theories of Stokes parametA new technology of lightning location is described, which is based on detecting the state of polarization (SOP) fluctuation of the laser light in the optic ground wire (OPGW). Compared with the conventional lightning location method, the new method is more accurate, more stable, and cheaper. Theories of Stokes parameters and Poincare sphere are introduced to analyze the SOP at the lightning strike point. It can be concluded that although the initial points of SOP on the Poincare sphere are random, the SOP fluctuation generated by lightning strike can still be accurately identified by detecting the velocity of polarization motion. A new algorithm to quantify the velocity is also introduced..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 712 (2006)
Supercontinuum generation from dispersion-flattened photonic crystal fiber using picosecond pulses
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We present the all-fiber system for supercontiuum (SC) generation with picosecond pulses. By launching 1.6-ps pulses from pulsed erbium-doped fiber laser (EDFL) into a section of photonic crystal fiber (PCF), the spectral broadening is observed. The bandwidth of 237 nm (at 20 dB level) is achieved.We present the all-fiber system for supercontiuum (SC) generation with picosecond pulses. By launching 1.6-ps pulses from pulsed erbium-doped fiber laser (EDFL) into a section of photonic crystal fiber (PCF), the spectral broadening is observed. The bandwidth of 237 nm (at 20 dB level) is achieved..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 715 (2006)
Study of passive Q-switching for flash-lamp-pumped 1.34-micron Nd:GdVO4 laser
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The static laser performance of a-growth Nd:GdVO4 crystal (a-cut, 4*4*25 (mm)) at 1.34 micron pumped by flash-lamp is investigated with different transmissions of output couplers. With the output coupler transmission of T=30%, the static output energy of 148 mJ is obtained when the pump energy is 35.2 J, and the corresThe static laser performance of a-growth Nd:GdVO4 crystal (a-cut, 4*4*25 (mm)) at 1.34 micron pumped by flash-lamp is investigated with different transmissions of output couplers. With the output coupler transmission of T=30%, the static output energy of 148 mJ is obtained when the pump energy is 35.2 J, and the corresponding electric-optical conversion efficiency is 0.42%. The Q-switched output of lasers with the output wavelength ranging from 1.3 to 1.6 micron can be realized by using Co^(2+):LaMgAl11O19 (Co:LMA) as saturable absorber. A flash-lamp-pumped, passively Q-switched Nd:GdVO4 laser with Co:LMA as saturable absorber is demonstrated in plano-concave laser cavity. With the cavity length of 16.3 cm and pump energy of 19.8 J, the single-pulse output energy, pulse width, and peak power are obtained to be 4 mJ, 80 ns, and 5*10^(4) W, respectively..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 718 (2006)
Methods of calibration to optical trapping force upon non-spherical cells
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The dynamical equation of a trapping cell is solved to find calibration methods for the trapping force, and two methods are compared by synthetic experiment data. Results indicate that: Boltzmann distribution method (BDM) is available for the force calibration of non-spherical or anisotropic cells in arbitrary trap potThe dynamical equation of a trapping cell is solved to find calibration methods for the trapping force, and two methods are compared by synthetic experiment data. Results indicate that: Boltzmann distribution method (BDM) is available for the force calibration of non-spherical or anisotropic cells in arbitrary trap potential; the mean square displacement method (MSDM) is available only for a symmetric harmonic optical trap. The spatial resolution requirement of the calibration system is about a nanometer. The results agree with the reported experiments..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 722 (2006)
Scanning Hartmann test method and its application to lens aberration measurement
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A scanning Hartmann test method is proposed and its measurement principle is described. The scanning Hartmann test setup is formed by modifying the Hartmann screen of the conventional Hartmann test setup. With the rotation of the scanning Hartmann screen and the improved hole arrangement, the whole information of the lA scanning Hartmann test method is proposed and its measurement principle is described. The scanning Hartmann test setup is formed by modifying the Hartmann screen of the conventional Hartmann test setup. With the rotation of the scanning Hartmann screen and the improved hole arrangement, the whole information of the lens to be tested in the full aperture can be obtained. The measurement accuracy of the aberration is improved and the local error of the lens can be got. In the method, no change of the Hartmann screen is needed for measuring the lenses of different aperture sizes. Experimental results of aberration measurements of two lenses are given to verify the usefulness of the setup..
Chinese Optics Letters
- Publication Date: Jan. 01, 1900
- Vol. 4, Issue 12, 725 (2006)
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