检索结果-内蒙古大学图书馆

Temperature drift modeling and compensation of fiber optical gyroscope based on improved support vector machine and particle swarm optimization algorithms

引用

APPLIED OPTICS 2016年第23期55卷 6243-6250页

作者： Wang, Wei Chen, Xiyuan Southeast Univ Sch Instrument Sci & Engn Key Lab Microinertial Instrument & Adv Nav Techno Minist Educ Nanjing 210096 Jiangsu Peoples R China

Modeling and compensation of temperature drift is an important method for improving the precision of fiberoptic gyroscopes (FOGs). In this paper, a new method of modeling and compensation for FOGs based on improved particle swarm optimization (PSO) and support vector machine (SVM) algorithms is proposed. The convergence speed and reliability of PSO are improved by introducing a dynamic inertia factor. The regression accuracy of SVM is improved by introducing a combined kernel function with four parameters and piecewise regression with fixed steps. The steps are as follows. First, the parameters of the combined kernel functions are optimized by the improved PSO algorithm. Second, the proposed kernel function of SVM is used to carry out piecewise regression, and the regression model is also obtained. Third, the temperature drift is compensated for by the regression data. The regression accuracy of the proposed method (in the case of mean square percentage error indicators) increased by 83.81% compared to the traditional SVM. (C) 2016 Optical Society of America

关键词： Fiber optics sensors Fibers polarization-maintaining Fiber Bragg gratings Lasers distributed-feedback

来源：评论

学校读者我要写书评

暂无评论

Experimental method based on wavelength-modulation spectroscopy for the characterization of semiconductor lasers under direct modulation

引用

APPLIED OPTICS 2004年第22期43卷 4446-4453页

作者： Schilt, S Thévenaz, L Ecole Polytech Fed Lausanne Swiss Fed Inst Technol Lab Nanophoton & Metrol CH-1015 Lausanne Switzerland

An experimental method is presented for characterization of the combined intensity and frequency modulation produced when the injection current of a laser diode is modulated. The reported technique is based on the analysis of the harmonic signals produced when a modulated laser is used to probe a gas absorption line by the so-called wavelength-modulation spectroscopy method. Based on a theoretical model of this technique, we present two methods that facilitate the determination of (i) the deviation in laser frequency and (ii) the phase shift between intensity and frequency modulation. These methods are illustrated experimentally by measurement of the modulation parameters of a 2-mum distributed-feedback laser by use of a CO2 absorption line. The experimental results have been compared with those obtained with another traditional method and have shown full agreement in the frequency range (400 Hz-30 kHz) considered. (C) 2004 Optical Society of America.

关键词： .deviation phase shift lock-in harmonic signals frequency modulation semiconductor lasers laser diodes theoretical model modulation frequency laser frequency distributed-feedback WMS Experimental method wavelength-modulation spectroscopy modulated laser modulation parameters

来源：评论

学校读者我要写书评

暂无评论

Ammonia detection by use of near-infrared diode-laser-based overtone spectroscopy

引用

APPLIED OPTICS 2001年第24期40卷 4387-4394页

作者： Claps, R Englich, FV Leleux, DP Richter, D Tittel, FK Curl, RF Rice Univ Rice Quantum Inst Houston TX 77251 USA

We describe a portable diode-laser-based sensor for NH3 detection using vibrational overtone absorption spectroscopy at 1.53 mum. Use of fiber-coupled optical elements makes such a trace gas sensor rugged and easy to align. On-line data acquisition and processing requiring < 30 s can be performed with a laptop PC running LabVIEW software. The gas sensor was used primarily for NH3 concentration measurements with a sensitivity of 0.7 parts per million (signal-to-noise ratio of 3) over a two-week period in a bioreactor being developed at the NASA Johnson Space Center for water treatment technologies to support long-duration space missions. The feasibility of simultaneous, real-time measurements of NH3 and CO2 concentrations is also reported. (C) 2001 Optical Society of America.

关键词： .quantum-cascade overtone ABSORPTION SPECTROSCOPY LabView CO concentrations NH concentration distributed-feedback DFB diode diode-laser-based measurements of NH simultaneous NH

来源：评论

学校读者我要写书评

暂无评论

Chirp evaluation of semiconductor DFB lasers through a simple Interferometry-Based (IB) technique

引用

APPLIED OPTICS 2016年第28期55卷 7788-7795页

作者： Nanni, Jacopo Barbiroli, Marina Fuschini, Franco Masotti, Diego Polleux, Jean-Luc Algani, Catherine Tartarini, Giovanni Univ Bologna Dept Elect & Informat Engn Viale Risorgimento 2 I-40136 Bologna Italy Univ Paris Est UPEM Le Cnam ESYCOM EA2552ESIEE Paris F-93162 Noisy Le Grand France Le Cnam ESYCOM EA2552 F-75003 Paris France

Direct modulation of a laser source is often utilized in realizing optical fiber connections where the cost of the entire system must be kept at a low level. An undesired consequence of this choice is the onset of the laser frequency chirp effect, which is detrimental in the case of either digital or analog links, and must be evaluated with precision in order to perform an accurate design of the whole system. Various methods of evaluation of the chirp parameters have been proposed, and the choice among them is typically made on the basis of the laboratory equipment available at the moment. This paper adds a further element to the set of possible choices, since it presents a method for the evaluation of the adiabatic chirp factor in distributed feedback (DFB) laser sources, which exploits a simple interferometric scheme, guarantees low cost, and shows, at the same time, good accuracy of the results. (C) 2016 Optical Society of America

关键词： Radio frequency photonics Interferometry Lasers distributed-feedback Lasers fiber Semiconductor lasers

来源：评论

学校读者我要写书评

暂无评论

Feasibility of cascaded multi-dithering technique for coherent addition of a large number of beam elements

引用

APPLIED OPTICS 2016年第15期55卷 4101-4108页

作者： Ahn, Hee Kyung Kong, Hong Jin Korea Res Inst Stand & Sci KRISS 267 Gajeong Ro Daejeon South Korea Korea Adv Inst Sci & Technol Dept Phys 291 Daehak Ro Daejeon South Korea

The capacity of cascaded multi-dithering technique in terms of scalability is analyzed by developing equations and performing simulations whose results are found to be in agreement with the earlier experimental result of a sixteen fiber beam combination using the cascaded multi-dithering technique. (C) 2016 Optical Society of America

关键词： Fiber optics sensors Fibers polarization-maintaining Fiber Bragg gratings Lasers distributed-feedback

来源：评论

学校读者我要写书评

暂无评论

Understanding the origin of the 535 nm emission band in oxidized poly(9,9-dioctylfluorene): The essential role of inter-chain/intersegment interactions (vol 14, pg 765, 2004)

引用

ADVANCED FUNCTIONAL MATERIALS 2004年第11期14卷 1037-1037页

作者： Sims, M Bradley, DDC Ariu, M Koeberg, M Asimakis, A Grell, M Lidzey, DG Univ London Imperial Coll Sci Technol & Med Blackett Lab London SW7 2BZ England

We present a careful study of the effects of photo-oxidation on the emissiveproperties of poly (9,9-dioctylfluorene) (PFO) that addresses important issues raised by a recentflurry of publications concerning the degradation of blue light-emitting, fluorene-based homo andcopolymers. The photoluminescence (PL) spectra of thin PFO films oxidized at room temperaturecomprise two major components, namely a vibronically structured blue band and a green, structurelesscomponent, referred to hereafter as the ''g-band''. These are common features in a wide range ofpoly(fluorene)s (PFs) and whilst the former is uniformly accepted to be the result of intra-chain,fluorene-based, singlet-exciton emission, the origin of the ''g-band'' is subject to increasingdebate. Our studies, described in detail below, support the proposed formation of oxidation-inducedfluorenone defects that quench intra-chain, singlet-exciton emission and activate the g-bandemission. However, whilst these fluorenone defects are concluded to be necessary for the g-bandemission to be observed, they are considered not to be, alone, sufficient. We show thatinter-chain/inter-segment interactions are required for the appearance of the g-band in the PLspectra of PFO and propose that the g-band is attributable to emission from fluorenone-basedexcimers rather than from localized fluorenone pi-pi* transitions as recently suggested.

关键词： LIGHT-EMITTING-DIODES LIQUID-CRYSTALLINE POLYFLUORENE OPTICAL MICROSCOPYNSOM CONJUGATED POLYMER POLARIZED ELECTROLUMINESCENCE MOBILITY ENHANCEMENT EXCIMER FLUORESCENCE distributed-feedback ENERGY-TRANSFER GREEN EMISSION

来源：评论

学校读者我要写书评

暂无评论

Pulse train uniformity and nonlinear dynamics of soliton crystals in mode-locked fiber ring lasers

引用

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 2017年第1期34卷 66-75页

作者： Jurgang, Defi Jr. Fandio Dikande, Alain M. Univ Buea Dept Phys Fac Sci Lab Res Adv Mat & Nonlinear Sci POB 63 Buea Cameroon

The evolution of soliton crystal structures is analytically and numerically investigated in passively mode-locked fiber lasers by means of the nonlinear rotation of polarization. Four parameters are considered as fluctuating canonical variables of the light propagating along the fiber ring: the polarization, the phase, the amplitude, and the chirp. The stability criteria define pulse train uniformity in the soliton crystal via stable phase-locking regimes at 0 and pi/2, with polarization-locked regimes prohibited due to strong amplitude polarization coupling and the bounded nature of the pumped signal. Numerical investigations of the phase-locked regimes also reveal a novel phenomenon that is the generation of spatial soliton lattices. We suggest this remarkable phenomenon results from the amplitude-chirp interplay that transfers the elliptic soliton profile of temporal pumps into spatially localized excitations upon round-trip tours in the fiber ring. (C) 2016 Optical Society of America

关键词： Fibers polarization-maintaining Pulse propagation and temporal solitons Lasers fiber Lasers distributed-feedback

来源：评论

学校读者我要写书评

暂无评论

High-power, micro-integrated diode laser modules at 767 and 780 nm for portable quantum gas experiments

引用

APPLIED OPTICS 2015年第17期54卷 5332-5338页

作者： Schiemangk, Max Lampmann, Kai Dinkelaker, Aline Kohfeldt, Anja Krutzik, Markus Kuerbis, Christian Sahm, Alexander Spiessberger, Stefan Wicht, Andreas Erbert, Goetz Traenkle, Guenther Peters, Achim Humboldt Univ Inst Phys D-12489 Berlin Germany Leibniz Inst Hochstfrequenztech Ferdinand Braun Inst D-12489 Berlin Germany Johannes Gutenberg Univ Mainz Inst Phys D-55128 Mainz Germany CALTECH Jet Prop Lab Pasadena CA 91109 USA

We present micro-integrated diode laser modules operating at wavelengths of 767 and 780 nm for cold quantum gas experiments on potassium and rubidium. The master-oscillator-power-amplifier concept provides both narrow linewidth emission and high optical output power. With a linewidth (10 mu s) below 1 MHz and an output power of up to 3W, these modules are specifically suited for quantum optics experiments and feature the robustness required for operation at a drop tower or on-board a sounding rocket. This technology development hence paves the way toward precision quantum optics experiments in space. (C) 2015 Optical Society of America

关键词： Atom optics Integrated optics devices Lasers and laser optics Lasers distributed-feedback Semiconductor lasers

来源：评论

学校读者我要写书评

暂无评论

Impact of nonstationary optical illumination on image reconstruction in optoacoustic tomography

引用

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2016年第12期33卷 2333-2347页

作者： Lou, Yang Wang, Kun Oraevsky, Alexander A. Anastasio, Mark A. Washington Univ Dept Biomed Engn St Louis MO 63130 USA TomoWave Labs Houston TX 77081 USA

Optoacoustic tomography (OAT), also known as photoacoustic tomography, is a rapidly emerging hybrid imaging technique that possesses great potential for a wide range of biomedical imaging applications. In OAT, a laser is employed to illuminate the tissue of interest and acoustic signals are produced via the photoacoustic effect. From these data, an estimate of the distribution of the absorbed optical energy density within the tissue is reconstructed, referred to as the object function. This quantity is defined, in part, by the distribution of light fluence within the tissue that is established by the laser source. Whenperforming three-dimensional imaging of large objects, such as a femalehumanbreast, it can be difficult to achieve a relatively uniform coverage of light fluence within the volume of interest when the position of the laser source is fixed. To circumvent this, researchers have proposed illumination schemes inwhich the relative position of the laser source and ultrasound probe is fixed, and both are rotated together to acquire a tomographic dataset. Aproblem with this rotating-illumination scheme is that the tomographic data are inconsistent;namely, the acoustic data recorded at each tomographic view angle (i.e., probe position) are produced by a distinct object function. In this work, the impact of this data inconsistency on image reconstruction accuracy is investigated systematically. This is accomplished by use of computer-simulation studies and application of mathematical results from the theory of microlocal analysis. These studies specify the set of image discontinuities that can be stably reconstructed with a nonstationary optical illumination setup. The study also includes a comparison of the ability of iterative and analytic image reconstruction methods to mitigate artifacts attributable to the data inconsistency. (C) 2016 Optical Society of America

关键词： Fibers polarization-maintaining Fiber Bragg gratings Lasers distributed-feedback

来源：评论

学校读者我要写书评

暂无评论

Fast generation of a high-quality computer-generated hologram using a scalable and flexible PC cluster

引用

APPLIED OPTICS 2016年第13期55卷 3681-3688页

作者： Song, Joongseok Kim, Changseob Park, Hanhoon Park, Jong-Il Hanyang Univ Dept Comp Engn & Software Haengdang 1 Dong Seoul 133791 South Korea Hanyang Univ Div Comp Sci & Engn Haengdang 1 Dong Seoul 133791 South Korea Pukyong Natl Univ Dept Elect Engn Daeyeon 3 Dong Busan South Korea

In order to efficiently generate a high-quality computer-generated hologram (HQ-CGH), which requires that both a three-dimensional object image and its computer-generated hologram (CGH) are in high-definition resolution, we implement a fast CGH generation system using a scalable and flexible personal computer (PC) cluster. From experimental results obtained in generating a HQ-CGH with a CGH resolution of 1536 x 1536 and 2,155,898 light sources using a PC cluster comprising a server PC and nine client PCs, it is verified that the proposed system is approximately 4.7 times faster than a single PC with two high-performance GPUs. (C) 2016 Optical Society of America

关键词： Fibers polarization-maintaining Fiber Bragg gratings Lasers distributed-feedback

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：