自聚焦棒外腔单频半导体激光器

本文提出了用振幅耦合因子描述激光器谐振腔与自聚焦棒光波导结构的差异及耦合腔的衍射损耗;讨论了自聚焦棒相对激光器作微小偏移对振幅耦合因子的影响.对自聚焦棒外腔半导体激光器的选模理论进行了实验验证.实现了单纵模运转,其边模抑制比大于35dB,线宽小于21MHz,最大的波长调谐范围为11nm.     

稳定大功率单频输出He-Ne激光器的新进展

继文献[1～3]之后,为了提高输出功率,并消除放电毛细管不规则带来的腔损耗,作者研磨了放电毛细管的内壁,将输出功率进一步提高到24mW。此时激光器的主要结构参数为:腔长1140mm,放电管长1m,放电管内径2.48mm;采用平凹腔结构,凹面曲率半径为4m,     

外腔谐振倍频单频红光激光器

利用全固化Nd:YVO4单频激光器连续输出的1.342μm激光,抽运由Ⅰ类临界相位匹配的LBO晶体构建的谐振倍频腔.当红外抽运光功率为1.14 W时,获得580 mW单频红光输出,最大倍频转换效率为50.9%.红光功率稳定性优于±0.5%(1 h),红外光频率漂移小于士2 MHz(1 min).     

近衍射极限输出的外腔半导体激光器研究

针对宽接触条形半导体激光器(Broad arealaser diode),设计了一个新颖独特的外腔结构,通过平面镜和光栅的组合外腔来改善光束质量.实验中在2.7倍阈值电流的驱动电流下,获得光瓣宽度(FWHM)为0.53°,相应于光束质量为1.3倍衍射极限,谱宽为0.7 nm,功率为320 mW的激光输出.     

外腔锁相改善半导体激光器列阵输出光束特性

采用一个由快轴准直透镜和一个高反射率平面镜组成的简单外腔,实现了半导体激光器列阵(DLA)锁相运行,改善了DLA的出射光束质量。DLA远场出现了3个瓣,每瓣发散角为10mrad左右;光谱从自由运行时的2 .2nm压缩到了0 .3nm ;阈值电流由7A降低到了5 .5A。     

外腔半导体激光器输出双稳环形状分析

研究了因折射率与载流子相互关联而引起的外腔半导体激光器的双稳特性，分析了不同条件下各种不同形状的载流子密度双稳环，计算了相应情况下的功率双稳环。     

外腔半导体激光器设计与高次谐波稳频

研究了利特罗(Littrow)结构外腔半导体激光器的结构参量对激光连续可调范围的影响。给出了反射镜转轴等处的机械加工误差对激光波长连续可调范围所造成的影响的数值计算结果。介绍了半导体激光器外腔结构设计的具体细节要点。利用该设计制作的外腔只需要配合商用半导体激光管便可以得到优质的780nm激光输出,经测量其线宽小于1MHz,连续可调谐范围大于3GHz。利用腔外Rb饱和吸收谱的三、五次谐波稳频方法对半导体激光器进行了稳频。其中提出了优化激光频率短期稳定度的方法,并对调制深度的选择给出了详细的理论解释。根据该优化方法设计出稳频系统对半导体激光器进行稳频,得到了稳定度达到10-12量级的半导体激光输出。     

半导体激光器高精度稳频输出控制系统

为了在光纤干涉仪中得到光源高精度稳频输出,采用高稳定度的恒温控制以及功率稳恒控制方法,通过高信噪比的运算放大器、半导体制冷器,设计了一种激光电源驱动系统,并进行了理论分析和实验验证。其能为半导体激光器提供温度控制精度在±0.01℃,制冷驱动电流可达800mA,同时使得半导体激光器输出波长控制精度在±0.1nm,驱动电流最大输出可达180mA,输出电流的稳定度为10-4~10-5。结果表明,该系统不仅结构简单,而且温度控制稳定、准确度高,可使半导体激光器的输出波长保持稳定,保证了干涉型光纤传感器的测量准确度以及在通信领域中的应用。     

调谐外腔半导体激光器输出双稳环的确定

在考察了外腔半导体激光器(ECLD)的振荡频率ν与激光二极管(LD)中载流子密度N(或增益g)、介质的折射率n以及LD第m个模式的共振频率νm间的关系之后,利用微扰法对LD的N-ν曲线上被前人错判为不稳定的两个关键区段重新进行了分析,结果表明这两个区段是稳定区段,据此,可以确定在对ECLD进行调频的过程中其增益介质的N-ν曲线上出现的双稳环.     

外腔半导体激光器的设计与高次谐波稳频

首先讨论了半导体激光器外腔结构参量对激光连续可调范围影响的理论计算方法,给出了Littrow结构外腔半导体激光器调谐范围的计算结果。然后介绍了半导体激光器外腔结构参量的具体设计,利用该设计得到了出射激光线宽小于1 MHz、连续可调谐范围可达3 GHz的780 nm波段外腔半导体激光器。接着讨论了利用腔外饱和吸收谱的三次谐波稳频方法对半导体激光器进行稳频,优化激光频率短期稳定度的方法。最后根据该优化方法设计出稳频系统对半导体激光器进行稳频,得到了稳定度达到10-12量级的半导体激光输出。     

Theoretical analysis of longitudinal mode coupling in external cavity semiconductor lasers

The single longitudinal mode behavior in long external cavity semiconductor lasers is discussed. Experimentally, the laser exhibits a single frequency oscillation even for an external cavity length of 100 cm. The mode selectivity of a composite cavity is shown to be insufficient to explain the experiments. Longitudinal mode coupling in semiconductor lasers is found to arise from an interference effect between the modes on the interband transition probability of electrons. Mode coupling equations are derived, which indicates that the single mode oscillation in long external cavity semiconductor lasers is brought about when the coupling strength goes beyond a critical value. It is shown that the effect of the hole burning in the external cavity semiconductor lasers is similar to that in the solitary laser.     

外腔半导体激光器的单纵模机制

本文建立了一种外腔半导体激光器单纵模机制的模相互作用模型。由于引入四波混频耦合项,模相互作用的效应对次级模的影响是对称的,均使次级模受到增益抑制。     

双稳外腔半导体激光器(ECLD)模式转换的数值描述

对多模半导体激光器(LD)的速率方程组进行了数值求解,分析了光栅双稳外腔半导体激光器(ECLD)模式发生跳变时的瞬态特性,讨论了光栅转角的大小对瞬态过程的影响。结果表明,当光栅转角较小时,ECLD在功率上跳过程中,切断模(switch offmode)在熄灭前可能会产生一个窄而强的光脉冲。这一现象在下跳过程中是不存在的。且上跳时,ECLD更快地达到稳态输出。     

Waveguide external cavity narrow linewidth semiconductor lasers

Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive and attractive candidate for many coherent applications due to their small size,volume,low energy consumption,low cost and the ability to integrate with other optical components.In this paper,we present an overview of WEC-NLSLs from their required technologies to the state-of-the-art progress.Moreover,we highlight the common problems occurring to current WEC-NLSLs and show the possible approaches to resolving the issues.Finally,we present the possible development directions for the next phase and hope this review will be beneficial to the advancements of WEC-NLSLs.     

Transient effects in external cavity semiconductor lasers

In several important applications of external cavity operated semiconductor lasers, including studies for FM optical communication and frequency stabilized lasers for coherent communication systems, the transient response of the laser is of crucial importance. In this letter, we present a first study of the transient optical response following a step current excitation applied to an AlGaAs laser operating in a dispersive external cavity. The study shows for the first time that, for optical feedback near the gain peak of the laser, a steady state is reached after only three roundtrips in the external cavity. However, for optical feedback far (∼100 Å) from the gain peak, 20 or more roundtrips are required before a steady state can be reached. It is also shown that under certain operation conditions the optical feedback can induce damped relaxation oscillations at each subsequent roundtrip in the external cavity.     

Effects of nonlinear gain on single longitudinal mode behavior of semiconductor lasers

The effects of nonlinear gain on the single longitudinal mode are analyzed by means of multilongitudinal mode and multitransverse mode rate equations and compared with the linear gain calculations and experments. It is shown that further suppression of the third order nonlinear gain on nonlasing modes always serves to accelerate the process of the single longitudinal mode operation and that results obtained with long cavity length are entirely contrary to those where only linear gain is considered. The experiments also show that single longitudinal mode lasers with even larger output power can be realized with long cavity length; and, with further proper reduction of the stripe width, single mode (single frequency) operation can be realized. But the results obtained from both gain considerations indicate that single longitudinal mode operation will be facilitated if the active layer is not too thin and the end face reflectivity is increased.     

Two-segment cavity theory for mode selection in semiconductor lasers

A simple three-mirror composite laser cavity is analyzed and optimum structures proposed in terms of the position of the central reflector and the value of its reflectivity in order to give single longitudinal mode operation. Two optimum structures are discussed, the first corresponding to relatively long cavities where a large period in the gain modulation is required in order to avoid a jump to the next mode with a high effective reflectivity, usually in a second mode group (as defined by a neighboring period of the gain modulation). The second corresponds to shorter lasers where jumps to neighboring modes should be avoided, since the spectral gain variation prevents jumps to other mode groups. The effects of mode discrimination due to external feedback have been analyzed and minimum values of reflectivity for the third mirror derived in order to preserve the internal mode selectivity.     

解析式表示外腔半导体激光器的特征参量

用射线法研究了强反馈可调谐外腔式半导体激光器的阈值行为，导出了ＥＣＬＤ被财在不同波长振荡所需的阈值载流子数密度外腔长度及阈值电流的解析表达式，也得到了不同电流ＥＣＬＤ的调谐输出功率及载流子密度的表达式。     

基于精密波长计的外腔半导体激光长期稳频系统

为抑制连续激光器的长期频率漂移,以精密波长计为参考频率标准,由计算机控制可实现连续激光无调制稳频.此方法从计算机获取波长计数据,利用数字比例积分微分(PID)计算出输出给激光器的反馈电压值,从而修正激光器腔长、实现激光器频率的锁定.此方法可用于目前商业激光器光谱范围内的任意波长,能在激光器频率可调节范围内任意频率点进行锁定.用此方法实现了对631 nm外腔半导体激光器的锁定,获得了1h频率不确定度为7.4 MHz、长期频率漂移率为±1.1 MHz/h的稳定锁定.