2013
2013
-
Record 241 of
Title:Numerical modeling and design of mid-infrared FBG with high reflectivity
Author(s):Chen, Yu(1); Li, Jianfeng(1,2); Yang, Yi(1); Chen, Ming(1); Li, Jing(1); Luo, Hongyu(1)Source: Optik Volume: 124 Issue: 16 DOI: 10.1016/j.ijleo.2012.07.016 Published: August 2013Abstract:Based on the coupled-mode equations and transfer matrix theory, the reflective spectrums of a silica FBG centered at 1.9 μm and a fluoride FBG centered at 2.8 μm with different length and refractive index perturbation were calculated, respectively. The results show that the peak reflectivity and the spectrum width increase and decrease with the increasing FBG length, respectively. An increase in refractive index disturbance quantity results in the increase of both reflective peak and spectrum width. Above 99% reflectivity with the spectrum width of ～0.6 nm can be achieved for the silica FBG at 1.9 μm when the length and refractive index perturbation are chosen in the range of 4.3-6.4 mm and 4.32 × 10-4-5.36 × 10-4, respectively. For the fluoride FBG at 2.8 μm, above 99% of the reflectivity with the spectrum width of ～0.75 nm can be achieved when the length and disturbance of refractive index are in the range of 6.0-8.0 mm and 4.53 × 10-4-6.0 × 10-4. ? 2012 Elsevier GmbH.Accession Number: 20132516438951 -
Record 242 of
Title:An Yb3+-doped Lu2SiO5 mode-locked laser using a reflective graphene oxide absorber
Author(s):Feng, Chao(1); Liu, Jie(1); Wang, Yonggang(2); Zheng, Lihe(3); Su, Liangbi(3); Xu, Jun(3)Source: Laser Physics Volume: 23 Issue: 6 DOI: 10.1088/1054-660X/23/6/065802 Published: June 2013Abstract:Reflective graphene oxide played the part of the saturable absorber to achieve a continuous wave mode-locking (CWML) laser based on Yb 3+:Lu2SiO5 (Yb:LSO) crystal for the first time. The laser operated at a repetition frequency of 87 MHz at a maximum average output power of 0.95 W with a single pulse energy of 10.9 nJ. A 9.8 ps ultra-short pulse was yielded at 1058 nm with a full width at half maximum (FWHM) of 2.09 nm, corresponding to a peak power of 1.11 kW. ? 2013 Astro Ltd.Accession Number: 20132216369223 -
Record 243 of
Title:The accuracy analysis of the intersection measurement on the moving ships
Author(s):Wang, Miao(1); Shan, Qiu-Sha(1); Liu, Kai(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8916 Issue: DOI: 10.1117/12.2035540 Published: 2013Abstract:Based on the princip le of the intersection measurement, the mathematical model of measuring the position and dimension of the moving ships was established, and the formu la of the metrical accuracy was deduced. The Matlab software was utilized to simu late and emulate the metrical accuracy, and analysed the primary errors of the system measurement accuracy; the measurement model is validated, co mbined with the examination. The result indicated that the method is feasible which utilized the measurement principle to measure the position and dimension of the moving ships, and establish the basical for further project application. ? 2013 SPIE.Accession Number: 20135117093551 -
Record 244 of
Title:Embedded optical waveguides fabricated in SF10 glass by low-repetition-rate ultrafast laser
Author(s):Bai, Jing(1,2); Long, Xuewen(1,2); Liu, Xin(1); Huo, Guangwen(1); Zhao, Wei(1); Stoian, Razvan(3); Hui, Rongqing(4); Cheng, Guanghua(1)Source: Applied Optics Volume: 52 Issue: 30 DOI: 10.1364/AO.52.007288 Published: October 20, 2013Abstract:Symmetric embedded waveguides were fabricated in heavy metal oxide SF10 glass using slit-shaped infrared femtosecond laser writing in the low-repetition frequency regime. The impact of the writing parameters on the waveguide formation in the transverse writing scheme was systemically studied. Results indicate that efficient waveguides can be inscribed in a wide parameter space ranging from 500 fs to 1.5 ps pulse duration, 0.7-4.2 μJ pulse energy, and 5 μm/s to 640 μm/s scan speed and pointing out the robustness of the photoinscription process. The refractive index profile reconstructed from the measured near field pattern goes up to 10-3. In addition, propagation losses of the waveguides are tolerable, with the lowest propagation loss estimated at 0.7 dB/cm. With a 5 μm/s scan speed and 3.5 μJ pulse energy in a high-dose regime, few-mode guiding was achieved in the waveguide at 800 nm signal injection wavelength. This is due to a combination of increased refractive index in the core of the trace and the appearance of a depressed cladding. ? 2013 Optical Society of America.Accession Number: 20134316904319 -
Record 245 of
Title:Laser contrast enhancement by non-collinear optical Kerr effect of CS 2
Author(s):Wu, Dengke(1); He, Junfang(1); Wang, Yishan(1); Wu, Zhen(1); Zhao, Wei(1)Source: Optik Volume: 124 Issue: 16 DOI: 10.1016/j.ijleo.2012.08.006 Published: August 2013Abstract:A pulse contrast enhancement method for lasers with a low initial contrast is presented based on non-collinear optical Kerr effect of CS2. The optical Kerr gate is used as a temporal filter to achieve a "cleaner" laser pulse. A pulse contrast enhancement factor of 104 is expected, with a maximum transmittance of the optical Kerr gate reaching 26%. Measurement of the pulse duration and profile has proved that this method introduces slight changes in the pulse. ? 2012 Elsevier GmbH.Accession Number: 20132516438979 -
Record 246 of
Title:A compact interferometer insensitive to scanning speed variations
Author(s):Yang, Qinghua(1); Zhao, Baochang(2); Zeng, Xiaodong(1)Source: Chinese Optics Letters Volume: 11 Issue: 2 DOI: 10.3788/COL201311.021202 Published: February 2013Abstract:A compact moving optical-wedge interferometer (CMOWI) is presented. This device consists of a moving optical wedge (MOW), a fixed optical wedge (FOW), a fixed compensating plate, and a beam-splitting cube. The optical path difference (OPD) is calculated and analyzed. The factor between the OPD and the displacement of the MOW is less than 1 if the refractive index and wedge angle of the MOW and FOW are chosen properly. Therefore, the CMOWI is insensitive to scanning speed variations compared with the traditional Michelson interferometer. The CMOWI is compact, small-sized, and suitable for low-resolution Fourier transform spectroscopy. ? 2013 Chinese Optics Letters.Accession Number: 20131516200535 -
Record 247 of
Title:The generating mechanism of strips and destriping algorithm of HJ-1A hyperspectral image
Author(s):Gao, Xiao-Hui(1); Xu, Guang-Hui(2); Yu-Tao(1); Wei, Ru-Yi(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8910 Issue: DOI: 10.1117/12.2034763 Published: 2013Abstract:Hyperspectral remote sensing images are affected by different types of noise. In addition to typical random noise, nonperiodic partially deterministic disturbance patterns appear in the data. The strips usually found in images acquired by push-broom sensors, which are characterized by a high degree of spatial and spectral coherence. Many strips-reduction approaches such as histogram matching and moment matching have been developed. These methods assume that all sensor elements observe similar subscenes in a given image and adjust the distributions of values acquired by each sensor to some reference distribution by means of a histogram or moment matching, but this assumption usually is failure in many scenes which contain diverse materials. The formation of strips has close connection with the image formation process of push-broom imaging spectrometers. Many causes such as the uniformity of the pixels, the push-broom mode and the asymmetric width of thin slit at the entrance of imaging spectrometers can induce the strips in the images. Comparing with the dispersive spectrometers, interferometer spectrometers acquire the interference data, obtaining the spectrum by using the Fast Fourier Transformation (FFT). By analyzing the generating mechanism of strips in push-broom interferometer imaging spectrometers, we proposed an approach that corrects the strips using relative calibration factor directly computed from the acquired image. Once the relative calibration factor is determined, all the images acquired by the same imaging spectrometers can be corrected. So the methodology is an efficient one to reduce the strips. A formula is set up to describe the connection between gray values of pixels in images and relative calibration factor. The developed methodology is tested on data acquired by HJ-1A Hyperspectral Imaging Spectrometers, which is an interferometer spectrometer put into operation in 2008. The shortwave bands of HJ-1A HSI have severe strips. Results show excellent rejection of the noise with respect to the original HJ-1A HSI images, improving the removal in those scenes with diverse materials as well as being high efficient. ? 2013 SPIE.Accession Number: 20141317516407 -
Record 248 of
Title:Spectrum reconstruction algorithms based on modern spectrum estimation
Author(s):Fu, Zhan-Fang(1); Liu, Xue-Bin(1)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 42 Issue: 9 DOI: 10.3788/gzxb20134209.1091 Published: September 2013Abstract:To overcome the shortcoming of the conventional spectrum recovery method, concepts and basic algorithms of a modern spectrum estimation are introduced. Two different methods (auto-Regressive parametric model and multiple signal classification algorithm) are used to reconstruct light spectrum from interferogram. Compared with conventional method for spectrum reconstruction, the modern spetrum estimation methods can well be adopted in spectrum reconstruction and perform excellently, especially when it is used to get higher spectrum resolution from a short series of data recorded.Accession Number: 20134216860618 -
Record 249 of
Title:Properties of waveguide induced by dark photovoltaic solitons in LiNbO 3:Fe crystal
Author(s):Zhang, Meizhi(1); Huo, Guangwen(2); Duan, Zuoliang(1); Hui, Zhanqiang(1); Zeng, Xiangmei(1)Source: Journal of Nonlinear Optical Physics and Materials Volume: 22 Issue: 3 DOI: 10.1142/S021886351350032X Published: September 2013Abstract:We investigate waveguides induced by dark photovoltaic solitons without background beam theoretically and experimentally in LiNbO3 crystal. Based on sole charge carrier band-transport model, we numerically simulate the transmission equation with shooting method, and find it single mode. Furthermore, we utilize two probe beams detecting the waveguide in experiments: one is continuous with wavelength of 632.8 nm; the other is femtosecond pulse of 800 nm. Comparing the two set of results, we conclude that the waveguides have basic mode only, while the femto-second pulse is more stable. Due to aforementioned stability of waveguide for femto-second pulse, it indicates the possibility of low power continuous beam controlling the high power laser pulse. ? 2013 World Scientific Publishing Company.Accession Number: 20193607411622 -
Record 250 of
Title:Influence of surface-profile error of larger mirror on aberrations characteristics of optical system
Author(s):Pang, Zhihai(1); Fan, Xuewu(1); Chen, Qinfang(1); Ma, Zhen(1); Zou, Gangyi(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 33 Issue: 4 DOI: 10.3788/AOS201333.0422002 Published: April 2013Abstract:Based on the wavefront aberration theory and the coordinates transform, the influence of surface-profile error of large mirror on aberration characteristic of optical system is analysed. The optical wavefront aberration and surface-profile error of mirror can be expressed as Fringe Zernike polynomial. The surface profile error on the surface of the system aperture diaphragm (exit pupil or entrance pupil) will introduce constant wavefront aberration coefficient in the full field by analysing the transformation matrix. The error on a surface not at pupil will lead lower order wavefront aberration coefficient in the optical system, the relation between different wavefront aberrations coefficient and fields is different, and the location zero for the lower aberration coefficient always resides at the center of the field of view. The result shows that it's possible to analyse the wavefront aberration caused by surface-profile error of the reflective mirror using coordinate transformation matrix for improving the efficiency of the alignment.Accession Number: 20132116362350 -
Record 251 of
Title:Dispersion imaging spectrometer for detecting and locating energetic targets in real time
Author(s):Yang, Qinghua(1); Zeng, Xiaodong(1); Zhao, Baochang(2)Source: Chinese Optics Letters Volume: 11 Issue: 6 DOI: 10.3788/COL201311.061202 Published: June 2013Abstract:A conceptual dispersion imaging spectrometer (DIS) is proposed. It consists of a telescope, four prisms, an imaging lens, and a detector. The first prism allows only the first set of wavelengths along the first direction to pass and disperse. The second prism allows only the second set of wavelengths along the second direction, which is perpendicular to the first. The third and fourth prisms are used to compensate for the angular deviations from the optical axes of the first and second prisms, respectively. The proposed DIS disperses the spectra of a target to form an L-shaped dispersion pattern (LDP). The theoretical calculation and numerical simulation of the LDP are presented. The DIS can locate multiple targets based only on data obtained from a single frame. It is suitable for detecting and locating energetic targets in real time. ? 2013 Chinese Optics Letters.Accession Number: 20133516678921 -
Record 252 of
Title:Design of athermal and bifocal infrared lens for space camera
Author(s):Wang, Hu(1,2); Luo, Jianjun(1)Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 25 Issue: 10 DOI: 10.3788/HPLPB20132510.2511 Published: 2013Abstract:A new kind of optical lens with light weight, compact structure, good image quality, all-weather work, scurviness environment is designed based on the triturating requirement of the space camera for debris. The lens breaks through the flaw that the conventional system always has complex structure, heavy weight, large volume, and only one focal.Diffractive optical element is used to calibrate the chromatic aberration and temperature difference by its characteristics. Ge and Si are utilized to calibrate the spherochromatic aberration. The result indicates that when spatial frequency is 16 lp/mm, the MTFs are above 0.45 and 0.55 in short focal and long focal, respectively. The MTF is approaching to the diffraction limit. The maximal RMS diameters of spot diagram are 15.8 μm and 7.2 μm in short focal and long focal, respectively, which are less than the diameter of detecting sensor. It shows that the image quality of the lens is very good, and it calibrates the temperature difference in real circumstance of the application.Accession Number: 20135217144964