LD泵浦高重频腔倒空Nd∶YAG激光输出研究

文中从声光腔倒空动态过程的速率方程出发,分析了腔倒空过程中,在光泵浦和倒空超声波脉冲序列的共同作用下,激光增益介质的反转粒子数密度及谐振腔光场变化的动态过程。以此为基础,讨论了声光腔倒空过程中影响激光倒空效率、激光脉冲形状等的关键因素,在理论分析的基础上,进行了LD泵浦Nd∶YAG声光腔倒空高重频激光输出的实验研究,获得了重复频率1. 2MHz、脉宽120ns、平均功率9W的腔倒空激光脉冲。     

LD泵浦高重频腔倒空Nd:YAG激光输出研究

文中从声光腔倒空动态过程的速率方程出发，分析了腔倒空过程中，在光泵浦和倒空超声波脉冲序列的共同作用下，激光增益介质的反转粒子数密度及谐振腔光场变化的动态过程。以此为基础，讨论了声光腔倒空过程中影响激光倒空效率、激光脉冲形状等的关键因素，在理论分析的基础上，进行了LD泵浦Nd：YAG声光腔倒空高重频激光输出的实验研究，获得了重复频率1．2MHz、脉宽120ns、平均功率9W的腔倒空激光脉冲。     

声光调制系统驱动器的研制

超短脉冲激光调制系统包括腔倒空驱动器、匹配网络和声光换能器。研制的激光脉冲调制系统运用锁相技术,采用单片、集成锁相环代替分立元件,实现了片内鉴频和鉴相,解决了高频信号传输的难题。研制的腔倒空驱动器能输出4 MHz、800 kHz、400 kHz、80 kHz、40 kHz、800 Hz、400 Hz等不同重复频率的脉冲信号,输出功率达到瓦级,满足了声光布喇格池的要求。匹配网络的加入使声光换能器充分吸收腔倒空驱动器输出的功率,增加衍射效率。激光脉冲调制系统已应用在皮秒时间相关单光子计数光谱仪系统中,在实际应用中取得了理想的效果。     

锁模激光器的声光腔倒空特性

资料[1]中实现了用锁模激光脉冲进行光学取样。本文使用同样的技术观察声光调制器进行腔倒空的激光输出中所出现的调制。资料[2～4]中证明了声光调制器作为激光腔倒空的一种手段的优越性。当腔光允许两次通过声盒时,每次都要衍射一部分光。当两束衍射光束一致并偏离腔时,它们就可用作腔倒空激光器的输出。然而由于声光调     

高峰值功率、高重复频率的腔倒空Nd:YAG激光器

在450兆赫起动射频(rf)输入功率为100瓦的声光石英调制器达到高倒空效率的Nd:YAG激光器的内凋制。在重复频率达到2兆赫获得稳定的输出脉冲为25毫微秒、峰值功率570瓦。指出在扰动出现的惰况下循环激光输出的波动确定腔倒空动态特性,并规定脉冲重复频率近似200千赫的较低极限。     

10kHz普克尔盒驱动器

1.引言最近我们研制了在1～2kHz范围工作的连续泵浦的Nd:YAG再生放大器。为了充分利用放大器提供的高重复频率优点,我们研制了一种以场效应晶体管和一个微波管为基础的新型普克尔盒驱动器。此驱动器可同时控制Q开关、籽脉冲注入和腔倒空。过去,需要几个电光或声光器件控制这三项工作。当用于再生放大器时,这个新的驱动器要求在激光腔内有单个的普克尔盒,以简化调整过程并减少腔内损失。     

Nd:YAG激光器的腔倒空单锁模脉冲

资料[1～2]研究了用双通声光调制器的腔倒空技术。单锁模脉冲的倒空通常用工业上现有的氩激光器。但是,由于声换能器的上升和下降时间及在声柱内光束宽,使这种倒空器的单脉冲能力限制它只能做长谐振腔激光器。往返时间具有2～4毫微秒的短谐     

声光腔倒空Nd:YAG激光器的理论分析

本文系统地分析和研究声光腔倒空Nd:YAG激光器的运转机理.建立了稳态(场能建立期)和非稳态(场能倒空期)速率方程。与最佳连续运转的Nd:YAG激光器参数联系起来。求解了腔内粒子场和光子场的解析解和数值解。文中详细讨论了声光调制器性能对激光脉冲特性的影响。     

共电极折叠腔窄脉冲射频波导CO2激光器设计分析

报道了共电极折叠腔电光腔倒空射频波导CO2激光器的设计方案,为在限定激光器体积的前提下大幅度地提高激光的输出功率,主振激光采用了Z折叠腔结构以及电光腔倒空方式输出激光.本振通道采用单通道结构.此激光器结构可以提高外差频率稳定度.理论分析了控制电光腔倒空过程激光输出波形的方法.     

12.5μJ电光腔倒空锁模皮秒激光器的实验研究

报道了单脉冲能量大于10μJ的腔倒空锁模皮秒激光器。通过实验完成了光纤耦合激光二极管端面抽运Nd:YVO4晶体、半导体可饱和吸收镜(SESAM)锁模的大功率皮秒激光振荡器后,在锁模腔内插入BBO电光晶体,实现重复频率1Hz～10kHz连续可调的电光腔倒空锁模运转。在抽运功率17.9 W时,获得了单脉冲能量12.5μJ、重复频率10kHz、脉冲宽度24.7ps的激光输出。     

Calculation of the minimum repetition rate of a cavity- dumped four-level laser

Calculations using the rate equations for an ideal 4-level laser system show that there is a minimum frequency below which efficient repetitive cavity dumping of a laser will not be stable. Expressions for the field and inversion variables are derived. Experimental results have been obtained using a folded cavity Nd-YAG laser that is perturbed by an intracavity acoustooptic modulator. The observed field inside the cavity is shown to behave like a damped harmonic oscillator. The minimum repetitive frequency,f, of Stable operation is shown to increase with increased pumping rate and system loss and decrease with increasing laser cavity length. As a result, the minimum stable frequency depends on the strength of perturbation of the modulator since this adds loss to the system. The range of stable operation for the Nd-YAG laser under investigation varies from 135 kHz to several megahertz.     

Tunable acoustooptic reflection filters in LiNbO3without a Doppler shift

A proposal is presented for an acoustooptic filter in LiNbO₃ without the Doppler shift, which is normally present in acoustooptic filters and which is undesirable as an intracavity element. This tunable filter has a significantly wider tuning range than previously demonstrated electrooptic filters. A structure incorporating an interdigital acoustic transducer, polarization filter, and single-mode optical waveguide is shown. The design presented works by cascading two acoustooptic filters with an intermediate polarizer, where the Doppler shift experienced in the first filter is precisely compensated for in the second filter. Hence, the output light of the two cascaded acoustooptic filters is not shifted in frequency, thus making the device suitable for applications inside a laser cavity. The filter with intermediate polarizer can be integrated with a single-mode waveguide and requires only a single interdigital acoustic transducer. Crystal symmetry and acoustic power considerations are treated in detail     

Polarization-independent acoustooptically tuned spectral filterwith frequency shift compensation

A new polarization-independent tunable spectral filter based on the combination of a single isotropic acoustooptic cell and a pair of conventional diffraction gratings is suggested and investigated. The filter features narrow bandwidth, frequency shift compensation, and low polarization dependence. Using standard AMTIR-1 chalcogenide glass acoustooptic modulator with frequency 40-77 MHz and ruled diffraction gratings with 600 grooves/mm, a 3-dB bandwidth of 1.1 nm, and a tuning range of 16 nm were obtained. Tuning range can be increased by the use of acoustooptic cell with increased center frequency or diffraction grating of a lower dispersion. Inserting the filter inside a laser cavity, continuous-wave tunable generation of Er-doped fiber laser with maximum output power 3 mW was realized. When a Fabry-Perot etalon (0.166-nm free spectral range, 40% reflectance) was inserted into laser cavity, the linewidth was observed to be less than 0.05 nm     

皮秒染料激光器的腔倒空的研究

本文叙述了腔倒空技术的原理并描述了皮秒染料激光器的腔倒空,研制了新的高频脉冲声光调制器,实现了皮秒染料激光器的腔倒空,并获得满意的倒空效果.     

The influence of external frequency shifted feedback on a DFB semiconductor laser

To investigate the possibility of optical isolation of a semiconductor laser using acoustooptic interaction, the influence of frequency shifted feedback on a DFB laser was studied experimentally. The isolation concept is based on a frequency shift of the laserlight by means of an acoustooptic Bragg deflection. This concept offers the opportunity of optical integration when Surface Acoustic Waves are used. In the experiments, a clear difference in laser performance between regular feedback and frequency shifted feedback was observed.     

Widely tunable single-frequency Er-doped fiber laser with longlinear cavity

A widely tunable single-frequency Er-doped fiber laser is demonstrated in a 21-m-long linear cavity incorporating all-fiber acoustooptic frequency shifters and a saturable absorption grating. Stable single-frequency operation is achieved with a sidemode suppression ratio higher than 50 dB and a wavelength tuning range greater than 40 nm     

A frequency-tunable mode-locked CW Nd:Glass laser

Mode locking and frequency tuning of a CW light-focusing Nd : glass laser called the SELFOC Nd : glass laser were achieved. Using an acoustooptic modulator having a modest degree of modulation (about 3 percent), almost perfectly mode-locked pulses as short as 49 ps were obtained. Pulsewidth was measured with an intensity-correlation method using the second-harmonic generation in KDP. Most of the observed shapes of the intensity-correlation curves were in agreement with theories previously presented by several authors. When the laser was mode locked, the long-term averaged optical spectrum was observed to narrow considerably. Some experimental evidence that the CW SELFOC Nd:glass laser could be considered to have a homogeneously broadened line was also found. Frequency tuning was achieved by using a tilted etalon in a cavity. When a 50-μm-thick etalon was used, the tuning range was more than 40 Å. Pulses obtained from a frequency-tuned mode-locked laser were as short as about 100 ps.     

Tuning fidelity of acoustooptically controlled external-cavitysemiconductor lasers

External cavity semiconductor lasers in extended- and ring-cavity configurations were tuned with chirp-compensating pairs of acoustooptic filters. Nanometer-size tuning gaps observed by previous workers were eliminated. The tuning range was approximately 80 nm for the extended cavity and at least 55 nm for the ring cavity. The root-mean-square tuning error was 0.036 nm for the extended cavity and 0.018 nm for the ring cavity. The output could be swept up to 35 mm in as little as 10 msec, limited by the radio-frequency generator. Transmittance measurements made on spare acoustooptic filters using the extended-cavity laser as a swept source were in good agreement with quasi-static measurements made using a grating-tuned laser     

Electronic tuning of a dye laser with simultaneous multiple-wavelength output

Rapid simultaneous multiple-wavelength tuning of a dye laser has been achieved electronically by inserting an acoustooptic beam deflector inside the laser cavity. A beam deflector and diffraction grating combination serve as the tuning element. By applying multiple-RF signals to the acoustooptic deflector, multiple-wavelength operation is readily obtained.     

Continuous-wave frequency synthesis of a laser diode based ondiscrete-time negative frequency feedback: II. Theory

For part I, see, ibid., vol. 31, no.6, p. 1038, 1995. In this paper, we present the theory for a novel lightwave frequency synthesis system demonstrated recently. The system is composed of a frequency stabilized master laser, a frequency tunable slave laser, and an active optical feedback loop with an acoustooptic frequency shifter. The reference frequency is synthesized by circulating the optical pulse from the master laser around the loop and one output pulse with the desired frequency shift is used to stabilize the frequency of the slave laser. The theoretical aspects of the frequency synthesis system are explained based on the control theory for discrete-time negative feedback. We evaluate the frequency stability numerically by means of the Allan variance for different sampling periods, and reveal the relation between the frequency fluctuation characteristics of the slave laser in its free running condition. The numerical results agree with those of the reported experiments