RTD在压力下的弛豫振荡特性

报道了共振隧穿二极管(RTD)在压力下的弛豫振荡特性.采用Pspice 8.0软件仿真并设计了振荡电路,测得其振荡频率达200kHz.在(100)半绝缘(SI)GaAs衬底上利用分子束外延(MBE)技术生长了AlAs/InxGa1-xAs/GaAs双势垒共振隧穿结构(DBRTS),并采用Au/Ge/Ni/Au金属化和空气桥结构成功加工出了RTD.由于RTD的压阻效应,采用显微喇曼光谱仪标定所加应力大小,对RTD在加压条件下的振荡特性进行了研究,结果表明其弛豫振荡频率大致有-17.9kHz/MPa的改变量.     

RTD在压力下的弛豫振荡特性

报道了共振隧穿二极管(RTD)在压力下的弛豫振荡特性.采用Pspice 8.0软件仿真并设计了振荡电路,测得其振荡频率达200kHz.在(100)半绝缘(SI)GaAs衬底上利用分子束外延(MBE)技术生长了AlAs/InxGa1-xAs/GaAs双势垒共振隧穿结构(DBRTS),并采用Au/Ge/Ni/Au金属化和空气桥结构成功加工出了RTD.由于RTD的压阻效应,采用显微喇曼光谱仪标定所加应力大小,对RTD在加压条件下的振荡特性进行了研究,结果表明其弛豫振荡频率大致有-17.9kHz/MPa的改变量.     

DPL中激光二极管噪声的传递特性研究

测量了几种激光二极管的噪声，并且理论分析了这种噪声向激光二极管泵浦固体激光器中传递的规律。发现低频噪声以相同的相对大小进行传递；而高频噪声则会被抑制；噪声频率接近弛豫振荡频率时，会被明显放大；等于弛豫振荡频率时会引起弛豫共振。     

固体激光器弛豫振荡尖峰脉冲参数的影响因素分析

利用固体激光器的弛豫振荡的尖峰脉冲特性,设计制作了一个窄脉宽、高重复频率的脉冲激光器。其方法是通过调节脉冲电流源的电流脉冲宽度,在固体激光器刚发出第一个尖峰脉冲时即关断泵浦电流。在实验中,对影响其尖峰脉冲参数的因素进行了探索,得出了尖峰脉冲的峰值功率、脉冲宽度与泵浦电流、腔长、输出镜透过率的关系,并从原理上对其进行了定性的分析和解释。基于实验及分析得到的结果,通过调整激光器的参数,设计出的脉冲激光器峰值功率能达到8W,脉宽能达到10 ns,重复频率可以达到百kHz的量级。文中的实验和分析结果对于固体激光器弛豫振荡的尖峰脉冲特性的理论认识及利用固体激光器弛豫振荡特性来设计脉冲激光器的参数设计都具有一定的指导意义。     

光纤激光器弛豫振荡特性研究

根据光纤激光器瞬态的速率方程,对F-P腔光纤激光器的瞬态输出特性进行了理论分析.采用数值计算方法对不同长度、不同腔面反射率、不同抽运功率下光纤激光器输出的弛豫振荡特性进行了模拟分析.结果表明弛豫振荡频率随光纤长度增加而减小,但是随抽运功率的变化很小.弛豫振荡幅度随抽运功率上升而增加,振荡的衰减时间随激光器腔镜的反射率的增加而上升,但是不随抽运功率变化.进行了975 nm抽运的Er/Yb共掺双包层光纤激光器的实验,实验表明理论分析得到的基本特性是合理的.     

连续Nd:YAG激光器弛豫振荡噪声

众所周知,连续Nd:YAG激光器输出中的弛豫振荡是频率范围在40～100千赫内主要噪声源之一。在连续工作中对将要激发的弛豫振荡来说,一定会存在某些扰动或起伏。资料[1]指出,激光棒和谐振腔轴的校正角明显影响这些噪杂波的产生,而资料[2]注意到减少冷却水流动,可以降低噪声。仅管有这些研究,但尚未分清哪一些扰动引起弛豫振荡。本文主要目的是要从实验上弄     

VCSELs与EELs多模弛豫振荡的研究

根据多模速率方程,利用MATLAB提供的SIMULINK软件包对垂直腔面发射激光器(VCSELs)和边发射激光器(EELs)多模弛豫振荡进行了研究。结果表明,与单模情况相比,多模时EELs弛豫振荡频率增大、弛豫和延迟时间缩短,而VCSELs动态特性变化不大。与此同时,在得出VCSELs的单模工作、高速调制以及提高偏置电流或自发辐射因子可改善两类器件动态特性等结论外还看到,VCSELs边模抑制比(SMSR)随偏置电流变化率高于EELs;自发辐射因子增大时,边模强度同比例增大、主模强度减小,利用微腔效应有效控制自发辐射因子可以优化VCSELs的单模特性。     

复合介质薄膜中的声子振荡弛豫

随着激光技术的发展，人们能获得的激光脉冲越来越短，这样，可以对物质在飞秒领域的超快现象进行直接的瞬态弛豫研究．超快光脉冲与物质的相互作用是科学与技术的一个前沿领域，利用超短激光脉冲诱导出样品中的非平衡态载流子，测量样品的瞬态光谱的变化是近年来发展的一种研究样品中非平衡态电子声子弛豫的新技术．在超快激光脉冲作用下引起样品瞬态光学透过率随时间变化的测量中，使用了飞秒脉冲激光器、泵浦-探测（PumP－Probe）技术、计算机控制的光学延迟线、锁定放大器及数据采集系统．激光脉冲宽度为165fs,波长为647urn，脉冲重复…     

光纤环形腔半导体激光器弛豫振荡的分析

通过建立光纤环形腔半导体激光器的单模速率方程,用小信号方法讨论了弛豫振荡与环形腔长度的关系,以及直接电流调制下的调制响应与调制带宽。分析发现,在确定的参数下,存在环形腔长度的临界值。只有当环形腔长度小于该临界值时,激光器才发生弛豫振荡。     

激光器弛豫振荡过程中光场的偏振特性

利用矢量型激光方程分析了激光器弛豫振荡过程中光场脉冲的偏振特性 .结果发现 ,在弛豫振荡过程中的光场具有线偏振特性 ,偏振方向随时间发生变化 ;在掺钕单横模光纤激光器的弛豫振荡过程中的光场表现出这种偏振特性 .     

Cavity decay rate and relaxation oscillation frequency inunconventional laser cavities

Measuring the relaxation oscillation frequency ω_r versus the normalized pumping rate r can provide a useful technique for determining either cavity or atomic parameters in many different kinds of lasers. Measurements of relaxation frequency versus pumping rate in a Nd:YAG laser using a gain-guided unstable-cavity design were recently found, however, to yield values of cavity decay rate which were unreasonably large compared to other estimates of the cavity losses. This difficulty has been resolved by a closer look at the relaxation oscillation dynamics in this type of laser. We find that in nonorthogonal laser cavities with nonuniform gain distributions the energy decay rate of the cavity oscillation mode usually employed in the relaxation frequency formula must be replaced by a different decay rate relevant to oscillation mode perturbations. A numerical simulation including this more general effect gives values very close to our experimental results, confirming the validity of this modified analysis     

High relaxation oscillation frequency operation of a QW-LD at thesecond quantized level

We describe a new approach for improving the relaxation oscillation frequency characteristics of quantum-well lasers at the second quantized level. Applying an antireflection (AR) and high-reflection (HR) coating to the laser facets suppresses lasing at the first quantized transition and promotes it at the second quantized transition. The relaxation oscillation frequency for the laser emitting at the second quantized transition is twice as high as that for the laser at the first quantized transition. The increase in the relaxation oscillation frequency of the laser operated at the second quantized transition is mainly due to the increase in the differential gain. Furthermore, the differential quantum efficiency increases to 0.5 in the AR/HR-coated laser     

Influence of lateral field on the relaxation oscillation frequencyof semiconductor lasers

We demonstrate theoretically that the lateral field distribution can be utilized to enhance the relaxation oscillation frequency of semiconductor lasers. It is found, for some laser parameters, that gain-guided semiconductor lasers with narrow stripe can exhibit higher relaxation oscillation frequency than index-guided devices     

高功率固体激光器激活介质的非辐射弛豫热吸收

分析了高功率固体激光器中激活介质的热吸收特征,建立了连续运转条件下激活离子的非辐射弛豫模型,给出激活介质非辐射弛豫热吸收对激光振荡的依赖关系,以及激光振荡条件对激活介质屈光度的影响,实验结果与理论模型分析一致。     

波长1.05微米和1.32微米的连续La_(0.1)Nd_(0.9)P_5O_(14)激光器

采用Ar~+离子激光器作为泵浦源实现了NdPP晶体的1.051微米和1.32微米的室温连续运转;采用准半共心腔获得低阈值运转.最低阈值吸收功率1毫瓦,最大输出功率达2毫瓦.由激光特性研究得到的受激发射截面σ_(1.051μ)=1.1×10~(19)厘米~2,σ_(1.32μ)=2.2×10~(-20)厘米~2.还研究了激光弛豫振荡现象,给出弛豫振荡频率与泵浦功率超阈值比的关系曲线;计算了不同输出功率时阈值泵浦功率密度与晶体长度的关系曲线.     

Optoelectronic feedback loop for relaxation oscillation intensitynoise suppression in Tm-Ho:YAG laser

An optoelectronic feedback loop that can be used to effectively reduce the intensity noise of a 2.1 μm Tm-Ho:YAG laser has been designed. The feedback circuit is based on a variable-gain biquadratic bandpass filter with adjustable central frequency and quality factor, providing a high loop gain around the relaxation oscillation frequency of the laser and a closed-loop phase margin larger than 50°. The relaxation oscillation peak in the intensity noise spectrum was completely suppressed in closed-loop operation, and a noise reduction of up to 24 dB was obtained     

光电反馈抑制掺铒光纤激光器的低频强度噪声

通过光电反馈电路对掺铒光纤激光器的中低频噪声进行了抑制。根据速率方程理论,分析了影响掺铒光纤激光器强度噪声的因素,通过电路仿真分析优化反馈电路参数,重点讨论反馈信号的相位对噪声抑制的影响。实验表明：激光器的低频(小于20KHz)强度噪声平均降低了10dB,中频弛豫振荡峰处（30KHz附近）抑制达35dB,并且克服了光电反馈抑制强度噪声使弛豫振荡峰向高频移动,导致高频噪声增大的问题。优异的噪声特性使光纤激光器在光传感领域具有很高的实用价值。     

掺钕单模光纤激光器的调Q实验研究

采用连续运转Ar+激光器5145 Å输出波长光作为泵浦源,采取端泵浦的平凹光学谐振腔结构,用光学斩波器作为Q开关,建立了掺钕单模光纤激光器的调Q实验装置,对这种激光器的调Q特性进行了实验研究和讨论。     

Effects of high density pumping on relaxation oscillations and mode spectra in lasers

Effects of high density pumping on relaxation oscillations and mode spectra are investigated in LiNdP4O12(LNP) lasers. It is shown that high density pumping reduces the spatial population inhomogenuity, which is due to periodic inversion saturation by a first lasing mode in the crystal, and results in spontaneous single longitudinal mode oscillations even at high excitation rates. Physical interpretations are given for single-mode operations on the basis of Auger recombination (annihilation) process for 1.048 and 1.32 μm quantums in LNP lasers. An effective diffusion parameter of excited states is shown in an increase with absorbed pump power density through the Auger process. Observed relaxation oscillation waveforms, which disagreed with the traditional laser dynamic theory, are found to be explained well by the rate equations, including the effective diffusion constant.