激光捕获系统的信号采集与处理

为了获得高对比度、宽测量范围的InGaAs红外焦平面探测器输出的视频图像,结合成像型激光捕获系统原理分析设计了焦平面探测器与LM98640模数转换芯片的接口电路。首先确定了LM98640的采样模式,并配置其内部参考电平以满足探测器输出信号的转换范围,同时保留一定余量使ADC满足较强激光入射时探测器输出更大范围信号的转换区间。实验结果表明,设计的系统能够实现波长532 nm、1064 nm和1550 nm的激光捕捉,利用软件对光斑图像进行处理可以获得入射激光的具体信息。系统可以实现空间可见光、短波红外范围激光信号的捕捉与识别,解决了较大范围波长内激光的识别问题,提高了输出图像对比度。     

全国产1550nm窄脉宽光纤放大器

本文分析了掺铒光纤长度与泵浦功率对放大器激光输出光谱及功率的影响,采用自制窄脉冲驱动电路,自制1550nm半导体光纤耦合模块作为信号光源,自制9xxnm的半导体光纤耦合模块作为泵源,优化光纤长度,实现了波长1550?6nm,脉宽8?8ns,峰值功率2?8k W光纤激光器输出,并对输出激光功率及光谱进行了分析,最终完成了全国产1550nm窄脉宽光纤放大器的研究。     

基于FPGA的可调谐激光器控制电路设计

可调谐激光器是光纤光栅解调系统中最主要的部件之一,其输出波长和功率的稳定性影响整个解调系统的性能;文中对MG-Y可调谐激光器的调谐原理进行了分析,设计了一种基于FPGA的可调谐激光器控制电路;使用温度控制芯片ADN8834对MG-Y激光器进行温度控制,通过改变电流源的输出电流,控制激光器的输出波长;利用光谱分析仪采集激光器的输出波长,并对激光器的输出波长进行标定,制作“波长-电流”查询表;FPGA通过调用“波长-电流”查询表,实现激光器的波长在1527~1567 nm范围内以20 pm间隔连续线性扫描。同时搭建光纤布拉格光栅解调系统,验证了可调谐激光器解调光纤光栅中心波长的可行性。     

光子晶体光纤激光器

大功率光纤激光器采用掺Yb3＋双包层光子晶体光纤作为增益介质，并采用典型的F-P腔结构，分别采用二色镜和光纤端面作为高反射腔镜和激光输出腔镜，用多模大功率980nm半导体激光器泵浦20米掺Yb3＋双包层光子晶体光纤，采用连续工作模式，获得了功率为15W的1．09μm激光输出。该器件性能稳定，转换效率高，达到国内先进水平。采用再生放大锁模钛宝石激光器产生的脉宽为200fs、250kHz和800nm的光脉冲泵浦保偏光子晶体光纤形成了谱宽超过两个倍频程的超宽连续谱并具有偏振特性。     

基于LabVIEW的CO激光器控制系统

针对液氮冷却的低温流动式可调谐CO激光器运行操作过程复杂、激光输出功率稳定性控制困难的问题,设计了CO激光器的计算机测量与控制系统,实现了CO激光器的自动运行控制;该系统采用了基于LabVIEW软件平台的多任务并行程序,结合虚拟仪器技术实现了对流动式CO激光器系统的真空度、4种工作气体的流量、2路放电电流和电压的实时监测与控制,以及对激光器运行波长的调谐和扫描控制;运行实验结果表明,激光器输出特性重复性好,功率稳定性优于1%.     

光纤激光腔内的传感技术研究进展

光纤激光腔内的传感技术已广泛应用于温度、应变、声波、振动、磁场和电压等物理量的检测,与传统的光纤传感器相比,光纤激光传感器具有抗电磁干扰、窄线宽和高信噪比等优势,其应用前景广阔.在此,综述激光腔内光纤传感技术的研究进展,阐述环形腔和线性腔两种不同的腔内结构,总结基于不同腔内结构光纤激光传感器的工作原理;此外,按照温度、溶液、磁场、应力/应变的分类对光纤激光传感器性能进行介绍,并对未来的应用前景进行展望.     

基于FPGA的光学微腔生物传感器控制系统

为了促进光学微腔生物传感技术向集成化、智能化和小型化发展,提出了一种基于现场可编程门阵列(FPGA)的数字辅助控制系统.系统通过三角波信号驱动可调谐激光器进入连续扫描模式,周期性扫描光学微腔谐振波长,得到激光中心波长信号的偏移量,从而得到光学微腔的灵敏度.设计了控制系统的硬件电路及软件辅助程序.经实验验证表明:控制系统实现了光学微腔生物传感器的数据采集处理以及对激光器的调谐.     

DBR光纤激光应变传感研究

光纤激光器是一种信噪比很高的优质光源,具有光束质量好、窄线宽、高功率等优异的性能,将光纤激光器应用于传感,能弥补布拉格光栅传感的不足.通过利用光纤激光器构成的光纤激光传感器与光纤布拉格光栅传感器相比较,进行应变传感实验研究.实验结果说明光纤激光器型传感器具有更高信噪比和输出功率.与传统的布拉格光栅比较,输出信号的功率增大了23 dB,信噪比得到19 dB的提高.线宽减少了约1/5.     

基于可调谐激光器的光纤法珀振动传感器解调技术

针对非本征型光纤法珀干涉仪动态解调,研究了一种基于可调谐激光器的双波长正交相位解调方案。可调谐激光器具有波长切换速度快、调谐范围广的特点,克服了传统双波长正交相位解调中光功率不平衡和直流分量难以计算的问题。利用可调谐激光器宽范围的线性扫描(1530-1560 nm)得到EFPI传感器的干涉谱,通过干涉谱计算出EFPI传感器的初始腔长122.581μm和直流分量3.4 V,同时确定两正交波长,然后利用反正切原理对EFPI传感器的腔长进行解调。搭建双波长正交相位解调系统,在2.25 kHz的频率以及不同的加速度下,对EFPI振动传感器进行解调。结果表明,该系统可实现不同腔长变化量的解调。     

放电等离子体烧结法制备的 Nd:Lu2O3 陶瓷的高效 激光运转

文章主要针对基于放电等离子体烧结方法制备的透明Nd:Lu2O3陶瓷激光性能展开实验研究.研究结果显示,退火后的Nd:Lu2O3陶瓷样品激光性能远优于退火前的样品:当采用直线腔测试方法时,退火后样品获得了最高功率为880 mW,最大斜效率为40%的输出;当采用V型腔测试方法时,退火后样品获得了最高为1.25 W,最大斜效率为38%的输出,输出光谱包含了两条位于1076.7 nm和1080.8 nm的谱线,但功率的进一步提高受到严重的热透镜效应限制.实验结果表明,通过放电等离子体烧结方法可以制备出高光学质量的Nd:Lu2O3陶瓷样品.     

Novel tunable laser sources with 1.5-μm and 1.57-μm cascaded DFB reflectors for in situ gas monitoring applications

Novel tunable lasers based on 1.5-μm and 1.57-μm cascaded distributed-feedback reflectors are realized for real-time monitoring of H₂O and CO gas mixtures immediately in multi-gas sensor systems. With simple fabrication procedures, the new design allows the realization of a widely tunable laser source that can cover the H₂O and CO absorption wavelength bands. With the temperature tuning of 0.1 nm/°C and current tuning of 0.014 nm/mA, the laser can be tuned to cover over 3 nm wavelength range in each wavelength band. Experiments verify that the lasers can have more than 38 dB SMSR over the tuning range. The characteristics of high power, excellent spectral purity, and simple wavelength switching control can simplify the analysis procedures of gas sensing and thus reduce the cost. By direct absorption method, the tunable laser has been successfully adopted in a diode laser sensor system for monitoring of water vapor concentration near 1.5 μm and carbon monoxide near 1.57 μm. Less than 15% error in the line strength is observed between the measured data and HITRAN database.     

一种基于温控半导体激光波长扫描的光纤瓦斯测量系统

设计了一种基于温控半导体激光波长扫描的光纤煤矿瓦斯测量系统,通过改变中心波长1653 nm半导体分布式反馈( DFB)激光器的工作温度来扫描半导体DFB激光器的输出波长,在5 nm波长扫描范围内,存在明显的瓦斯气体吸收峰。半导体DFB激光器输出的光注入被测气体室,气体室的输出光携带有瓦斯气体浓度信息,用光电探测器将光信号转化为电信号,再由A/D采集卡采集到信号处理系统,通过对有吸收峰位置的光功率和无吸收峰位置的光功率进行比较,则可计算出瓦斯浓度。该传感系统采用80 mA恒流源驱动半导体DFB激光器,使其输出光强保持不变,其结构简单、灵敏度高。     

Micromachined widely tunable vertical cavity laser diodes

Wavelength tunable vertical-cavity surface-emitting lasers (VCSELs) are potentially useful for future optical communications. Traditionally, the emission wavelength of a vertical cavity laser was tuned by modulating the active region temperature. However, thermal tuning is slow, and the realized tuning range is quite limited. Micromachined tunable VCSELs (Mi-T-VCSELs) combine the traditional vertical cavity laser structure with a monolithically micromachined deformable membrane, enabling continuous wavelength tuning without mode hopping. In addition to a large wavelength tuning range, this technique does not suffer from the shortcomings of the thermal tuning technique. This paper presents the background theory, processing sequence, and experimental results for Mi-T-VCSELs     

基于改进的PID算法的光模块设计和实现

讨论了基于100G可调谐激光器光模块的设计与实现,简单介绍了MCU中各个模块功能。主要的技术涉及TEC控制、波长锁定、波长调谐和功率补偿等。通过分析传统的位置式PID算法,改良PID算法并使用该算法实现波长锁定,这样可以防止在系统调整过程中,因调整量过冲而发生的波长漂移甚至失锁。     

Measurement of the pressure broadening coefficients of the oxygen A-band using a low cost, polarization stabilized, widely tunable vertical-cavity surface-emitting laser

Vertical-cavity surface-emitting lasers (VCSELs) are used for oxygen monitoring via tunable diode laser spectroscopy at 760 nm wavelength. For the desired application, novel polarization-stable laser diodes based on AlGaAs were developed. We present measurements of the pressure-broadening coefficients of the electric dipole forbidden oxygen A-band b ¹ Σ₊ ^g → X ³ Σ₊ ^g transition at 760 nm. The time the pressure-broadening coefficients were determined with a temperature tuned VCSEL. Generally temperature tuning has the disadvantage of frequent mode-hops, but the advantage of a wider tuning range in comparison to current tuning. Because of special techniques of polarization stabilization with a combination of a dielectric surface grating and a surface relief the VCSELs have a mode hop-free tuning range of more than 7 nm and a sidemode suppression of more than 30 dB. This provides a low cost laser diode system with a wide tuning range, which enables the possibility of simultaneous measurement of temperature, pressure and oxygen concentration in air, high pressure measurements and also a higher accuracy of oxygen concentration measurements.     

Reducing Brownian motion in an electrostatically tunable MEMS laser

Brownian motion of a tunable vertical-cavity surface-emitting lasers (VCSEL) movable microelectromechanical systems (MEMS) mirror is shown to broaden the spectral width of the laser emission line. A low-noise wavelength feedback system is presented and evaluated. This feedback system is employed to reduce measured linewidth from 1050 to 400 MHz fullwidth at half-maximum (FWHM), an improvement of 62%. The effects of device design parameters on closed-loop Brownian motion levels are analyzed. The potential increases in performance resulting from vacuum packaging and advanced controller design are discussed.     

The emission characteristics of liquid‐crystal lasers

Abstract— Liquid‐crystal lasers exhibit narrow linewidth, large coherence area, and low threshold laser emission. Moreover, the wavelength of the laser line can be readily tuned using a variety of different external stimuli, including electric fields. These combined features make them particularly attractive as compact tunable laser light sources. Recent experimental results with regards to the emission characteristics of chiral nematic photonic band‐edge lasers are discussed. This type of liquid‐crystal laser consists of a self‐organizing one‐dimensional photonic band structure and a gain medium in the form of a laser dye. Some of the generic features that are observed for these lasers are discussed, including the typical emission linewidth of the laser line, the change in emission energy of the laser for high excitation energies and high pump repetition rates, and the dependence of the excitation threshold and slope efficiency on the cell thickness. In addition, how the performance changes when either the molecular structure of the chiral nematic host or the gain medium is varied is considered. To conclude, results are presented on the laser emission for a wide‐temperature‐range blue phase I band‐edge laser which consists of a self‐organizing three‐dimensional photonic band structure.     

Fiber laser-based temperature sensor systems using uniform wavelength-matched Bragg grating reflectors

A detailed investigation has been carried out into the output characteristics of a fiber laser forming, as it does the basis of an optical sensor system, in terms of its wavelength, signal intensity and linewidth, and the output spectrum when each individual fiber Bragg grating, acting as the reflectors of the laser system, has been allowed to respond to temperature in a wavelength-matched normal Bragg grating-based laser configuration. An analytical model has been created reflecting the relationship between the grating bandwidth and the temperature under each operational condition and the results obtained have significant implication for the optimum design of this type of fiber laser-based sensors. Additionally, experiments were performed to investigate the output characteristics of a fiber laser-based sensor when used for temperature measurement.