A theoretical study of pulsed laser sampling photon amplifiers

Theoretical studies point to significant improvements in the performance of semiconductor laser amplifiers by injecting carriers with pulsed electric currents of sub-nanosecond duration. A pulsed Fabry-Perot amplifier (FPA) is most sensitive to input lightwave at the instant the carrier density is crossing the critical region, and gives a sharply pulsed sampling effect on the input lightwave signal. Compared with a FPA operating at subcritical electron density, the pulsed amplifier gives much higher gain, peak power, and bandwidth. In fact, pulsed operation of a FPA is also expected to give significantly higher gain and about the same peak output power as a traveling wave amplifier. Pulsed operation also improves the performance of a traveling wave amplifier by attenuating its internally reflected waves     

Optical sampling using nondegenerate four-wave mixing in asemiconductor laser amplifier

Picosecond optical sampling using nondegenerate four-wave mixing in a semiconductor laser amplifier (SLA) is demonstrated for the first time. High-peak-power pulses and electrical gating of the SLA produce an optical sampling signal with a high signal-to-noise ratio     

A sampling amplifier

A method of amplifying wide-band sisnals using narrow-band amplifiers is proposed. It uses the principle of undersampling a signal and amplifying the narrow-band signals generated by several sets of undersamples of the signal.     

Pulsed Ho:YAG oscillator and amplifier

A pulsed Ho:YAG system has been investigated both as an oscillator and an amplifier. The oscillator was operated normal mode in the TEM00mode with a slope efficiency of 0.012. WhenQ-switched, the laser produced in excess of 80 mJ per pulse with a pulse length of about 30 ns. The predictions of pulse length and energy are in fair agreement with a simple theory presented within. The Ho:YAG was also operated as an amplifier. Large signal gains in excess of 2.0 were observed, which is closely comparable with theoretical predictions. Mode-locked pulses, with a pulse length of about 0.57 ns, were produced by using an acoustooptic mode locker.     

Many-pass resonant laser amplifier

A very high gain amplifier has been developed by arranging for many amplifying passes to be made through one system. Input pulses of millijoule energy have been amplified to the damage limit of the materials (∼10 J/cm²) by this method. One such system can replace several when amplification of low-energy pulses is required.     

脉冲激光波长计

本文回顾了脉冲激光波长计的发展过程。介绍了有代表性的二种脉冲激光波长计。简要介绍了我们研制脉冲激光波长计的工作。     

Noise in free-electron laser amplifier

The equations of the free-electron laser amplifier are generalized to include higher order modes. The density and velocity fluctuations in the entering electron beam cause noise excitation in the amplifier. The electron beam fluctuations have been studied extensively, both theoretically and experimentally, in traveling wave tubes, and hence the well-tested formalism developed for this purpose is conveniently applied to the present problem. It is found that the fluctuations put a severe constraint on the achievable exponential gain in a proposed Raman-type free-electron laser operating at optical frequencies. A1/lambda^{3}scaling law is derived.     

一种准分子激光泵浦的微微秒染料激光脉冲放大器

本文叙述一种在一个泵浦周期内讯号脉冲三次通过染料池的微微秒激光脉冲放大器,它有效地利用泵浦能量,可以得到4×10~4的高增益,低的放大自发荧光以及没有脉冲变宽,并且结构简单,工作稳定。用四能级分子模型,以及作速率方程的数值解,对放大器的特性做了计算机模拟。计算与实验结果相符。     

用于光子计数单像素成像的去块状采样网络

将光子计数技术和单像素成像结合,能实现高灵敏、低成本的光子计数成像,但存在采样时间和重建时间长的问题。基于深度学习的压缩采样和重建网络,将去除偏置和激活函数的全连接层作为测量矩阵,通过从数据中学得高效的测量矩阵和避免传统迭代算法带来的巨大计算量,实现了更快、更高质量的图像重建。但利用全连接层进行高分辨图像的分块压缩感知时,重建图像会产生块状效应。针对该问题提出了重叠分块采样网络（Os_net）、嵌套采样网络(Ns_net)、卷积采样网络（Cs_net）等三种方法以取代全连接层采样。在重建网络的设计中,使用线性映射网络对图像进行重建,设计实验结果表明Cs_net的去块状化效果最好。将Cs_net二值化后应用于光子计数单像素成像系统,实验结果表明Cs_net除块状化明显优于传统算法TVAL3,且Cs_net在重建质量上也同样取得了较好的效果。     

GaAs-GaAlAs phototransistor/laser light amplifier

A hybrid light amplifier consisting of a GaAs-GaAlAs widegap phototransistor as light detector and a d.h. laser as light emitter has been realised. Amplification up to 25 dB has been achieved. Fastest turn-on and turn-off times were 16 ns and 24 ns, respectively. A monolithically integrated amplifier structure is proposed.     

Flashlamp-pumped Cr:LiSAF laser amplifier

A flashlamp-pumped Cr:LiSAF laser amplifier has been developed that is capable of producing ultrashort pulses with a peak power of ~TW. A systematic experimental study of laser oscillation, its small-signal gain, and chirped-pulse amplification has been performed under the same pumping conditions. The characteristic properties and performance of the Cr:LiSAF laser amplifier are reported     

Traveling wave semiconductor laser amplifier detectors

Near-traveling-wave semiconductor laser amplifiers for amplification and detection of optical signals are discussed. Measurements of gain, responsivity, and bandwidth are presented and compared with theory. The system performance of the laser amplifier detector is evaluated by a digital transmission experiment. The importance of using low-reflectivity amplifiers with high-responsivity and weakly wavelength-dependent devices is revealed by computer simulations. The various noise contributions of the laser amplifier detector are analyzed. Expected sensitivity values are given, and it is shown that there exists an optimum amplifier gain with respect to sensitivity     

双程放大碘原子激光放大器

本文报道了双程放大碘原子激光放大器的实验结果。在低于饱和放大区工作,利用双程放大大大提高了放大器的效率。此外,实验发现He是最佳的缓冲气体,尤其在减小光泵引起的波前畸变,以及光束热稳定方面比其它缓冲气体明显优良。     

小型飞秒激光脉冲放大器

在放大器谐振腔内插入一对棱镜,使飞秒脉冲信号边放大,边展宽。既防止了强光的自聚焦效应,又减小了整个放大器占用空间。输出光再经过另一对棱镜压缩,得到的脉宽小于100fs,重复率10kHz,平均功率达到0.2W。     

Characteristics of a gas laser amplifier

Characteristics of a gas laser amplifier are theoretically analyzed by employing Lamb's model. A wave equation in the time domain is obtained when traveling waves in the positive and negative directions are present simultaneously in the nonlinear active medium. The wave equation which contains linear and third-order nonlinear terms is applicable to any spectral construction of the incident signal, such as discrete, continuous, and mixed. An approximate solution of the wave equation is obtained in the frequency domain. Some characteristics of a kernel which appears in the frequency-domain representation are discussed. As an application of the theory, characteristics of one- and two-frequency amplifiers are calculated and compared to previous analysis.     

Signal detection with a laser amplifier

The use of signal-to-noise ratio as a figure of merit for a signal detection system involving a threshold detector may lead to erroneous conclusions when the signal strength, in absolute terms, is small. Recourse to approximate or exact distributions must be made and the notion of statistical separation must be employed. A new figure of merit utilizing the idea of statistical separation is defined. The method is applied to the question of the efficiency of a laser amplifier in a pulse detection system.     

LD泵浦再生放大器技术研究

再生放大器作为一种具有极高增益的前置放大器,在获取窄脉宽、高峰值功率激光过程中具有重要作用。本文对再生放大器的传统光路进行了改进,通过光路设计与精确时间控制,将脉冲单选功能集成到再生放大过程中,进行了腔内单选再生放大器技术研究,实验证明这种改进是完全可行的。     

板条型脉冲Nd∶YAG激光器的研究

本文研制了尺寸为124×12×6mm~3的Nd:YAG晶体板条型脉冲激光器,自由振荡单脉冲输出24J,器件总体效率2.5％,电光调Q单脉冲输出860mJ,脉宽12～15ns,Q开关效率72％。