Pulsed laser sampling photon amplifier

The performance of semiconductor laser amplifiers can be significantly improved by injecting carriers with pulsed electric currents of subnanosecond duration. Pulsed operation is illustrated in a Fabry-Perot amplifier and in a traveling-wave amplifier. The resonant amplifier is most sensitive to an input light wave at the instant the carrier density is crossing over the critical region, giving a sharply pulsed sampling effect on the input light wave signal. Compared to a resonant amplifier operating at subcritical electron density, the pulsed amplifier gives much higher gain and peak power. In fact, pulsed operation of a resonant amplifier is also expected to give significantly higher gain than 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.<>     

1550nm单频脉冲光纤激光放大器实验研究

为了满足相干探测技术对激光光源的需求,采用主振功率放大技术,对全光纤、高重复频率、1550nm单频脉冲光纤激光器进行了研究.得到了脉冲宽度400ns、重复频率10kHz、单脉冲能量14μJ、平均功率148mW的单模光纤激光脉冲输出.实验中还发现了光纤中过高的功率密度所引起的受激布里渊散射(SBS)将导致激光脉冲波形的变...     

Noise properties of pulsed ruby laser amplifiers

The spontaneous emission noise properties of a pair of pulsed ruby laser amplifiers have been studied. Absorption and scattering loss measurements coupled with gain measurements as a function of pump time gave a measure of the inversion attained in the amplifiers. The high inversions reached enabled the authors to overcome the inherent noisiness of a 3-level system by having N2considerably larger than(m_{2}/m_{1}) N_{1}. Total spontaneous emission power was measured at gain saturation for each amplifier. Comparison of the observed with the theoretically expected spontaneous noise power gave good agreement.     

A theoretical and experimental investigation of Fabry-Perot semiconductor laser amplifiers

A simple model for the characteristics of Fabry-Perot type semiconductor laser amplifiers is developed, the model leads to several simple analytic expressions. The theoretical results have been compared with measurements using a 1.3 μm laser as an amplifier. Our results are compared to those of other authors, and we indicate how the model can be used to optimize the amplifier performance.     

On the design of pulsed dye laser amplifiers

We apply a formula for the small signal gain of a dye laser amplifier (obtained and verified in a previous work) to the case of a transverse pumped R6G amplifier. We trace a set of curves as a function of dimensionless parameters which give the gain for any combination of the parameters characterizing the amplifier (dye concentration, active length, etc.). The curves can be applied to design dye laser amplifiers for ultrashort pulses, both with saturated or unsaturated gain. We give numerical examples of the use of those curves that suggest that the new designs would require much lower pumping energies than the previous ones. Similar sets of curves can be easily obtained for other dyes or pumping configurations.     

4.7--Coherent phasing of repetitively pulsed laser amplifiers

Recently completed experiments demonstrated the feasibility of a coherent optical array, using 1.06-micron laser components. This paper reports on automatic techniques used to control the relative phase of Nd :glass power amplifiers with gains up to 10 dB. Both amplifiers, fed from a master oscillator, were pumped repetitively at rates of one pulse per two seconds.     

Calculation of photon and current fluctuations in traveling-wavesemiconductor laser amplifiers

The noise properties of semiconductor laser amplifiers are calculated using the Heisenberg equations of motion. Photon noise as well as the recombination current noise are calculated with this formalism, and agreement with previously published results was found for the photon noise. The formalism also gave the conventional current shot noise in the appropriate limits, e.g., when using the amplifier reverse-biased as a detector. The method gives reasonable agreement with reported experimental results and the results for the current noise could be given a consistent physical explanation. Some concluding remarks concerning the relationship with the Langevin approach and the possibilities of minimizing the noise are given     

高功率激光通过多级和多程脉冲放大器的传输特性

采用脉冲序列模型和薄片模型,对任意空间和时间分布波形的激光通过任意增益分布多级和多程脉冲放大系统的传输特性作了详细研究。     

A theoretical description of the 5106-Å pulsed copper vapor laser

A theoretical model that accounts for the experimentally observed features of the 5106-Å pulsed copper vapor laser has been devised. The electron excitation and ionization cross sections used in the theory were calculated by the use of the classical Gryzinski-type methods.     

GaAs laser amplifiers

Experimental results are presented on the operational characteristics of GaAs laser amplifiers very closely coupled to a laser oscillator. The separation between the oscillator and the amplifier was varied from 0.2 to 2.0 microns. The amplifiers were made by lapping one end at an angle of 10 to 15 degrees. This angle is several times larger than the critical angle for confinement of radiation in GaAs lasers that is estimated from experimental data to be between 2 and 3 degrees. The measured signal gain is a decaying function of input power and approaches a value of 2 to 4 for large input signals. A maximum amplifier gain of about 150 was obtained for an input signal of 2 mW/mil junction width (corresponding to an optical flux-density of about 8 kW/cm²incident on the input side of the amplifier). At this input power level, the output fluoresence is reduced by about 50 percent and the internal oscillatory modes of the amplifier are almost completely quenched. The ratio of the oscillator output actually coupled into the amplifier to the measured output from the oscillator was estimated from gain saturation measurements. It was found to be inversely proportional to the cleaved separation between the oscillator and the amplifier and was estimated as 0.5 and 0.07 for separations of 0.2 and 2 microns, respectively. The output quantum efficiency of the laser amplifier was demonstrated to be comparable to the output quantum efficiency of a single oscillator. Tests of a new structure for a low-noise, constant-gain laser amplifier are described.     

A theoretical study of saturation effects in three-level laser systems

Exact numerical solution of a time-space (one dimensional) three-level lasing system (homogeneously broadened) is used to study the relevance of steady-state models to such a system. This study revealed: 1) the existence of two disconnected (quasi) steady-state regions-the small-signal gain region (slow pumping rate) and the high saturation region (large pumping rate), and 2) the spatially averaged equations for the high saturation region have a form similar to those usually employed in the small-signal gain region, except that a constant which in the latter case is unity becomes smaller than 1 in the high saturation region.     

脉冲Xe离子激光器

本文报导了一台小型脉冲Xe离子激光器.激光器峰值功率150瓦,在4300～6300埃中获得10条振荡谱线,激光脉宽为0.2～1微秒,放电电压4～12千伏,充气压0.1～9毫托.     

A power re-use technique for improved efficiency of pulsed oscillating amplifiers

This letter presents a power re-use technique for pulsed oscillating amplifiers. By rectifying the upconverted switching harmonics of the pulsed oscillating output, some portions of wasted power can be returned to the power supply. The efficiency of the amplifier can be enhanced without degradation of the linearity. The measured results show that the overall efficiency of the amplifier with power re-use is improved up to 22% compared to the pulsed oscillating amplifier without the power re-use at the PCS band.     

脉冲激光沉积制备Ge纳米薄膜的研究

利用脉冲激光沉积(PLD)技术,在Ar环境下于Si基片上制备出Ge纳米薄膜.用X射线衍射(XRD)仪和原子力显微镜(AFM)观测了薄膜的微观结构和形貌,分析了它们随激光能量密度和衬底温度的变化情况.结果表明:Ge薄膜在室温下即可以结晶,其平均品粒尺寸随脉冲激光能量密度的增大而增大.当脉冲激光能量密度为0.94 J/cm2时,所制备的薄膜由约13 nm的颗粒组成;当脉冲激光能量密度增大为1.31 J/cm2时,颗粒的平均尺寸增大为56 nm,凡薄膜表面变得比较均匀.此外,当衬底温度从室温升到450℃过程中,晶粒平均尺寸随温度升高而增大.在实验基础上,对薄膜的生长机理进行了分析.     

纳秒脉冲半导体激光驱动器的研究

为了获得高功率、高重复频率的纳秒级光脉冲,介绍了一种基于Marx bank脉冲发生原理的纳秒脉冲激光驱动器的设计,以及设计过程中雪崩晶体管的选取.该驱动器采用一级小雪崩管对触发脉冲进行陡化,由小雪崩管产生的脉冲对Marx bank电路进行触发,以获得大电流窄脉冲,用于驱动半导体激光器.设计所得驱动器的峰值电流为12.5A、半峰全宽为1.51ns、重复频率为100kHz,实现了大幅度纳秒脉冲半导体激光驱动器的设计要求.结果表明,对触发脉冲的陡化,可以降低后一级Marx bank电路的雪崩电压,同时使得脉宽更窄,这将更加有利于驱动半导体激光器.     

A theoretical study of the atmospheric pulsed H2+ F2chemical laser including rotational nonequilibrium effects

An atmospheric pulsed F2/H2/He chemical laser is studied numerically by a model which incorporates rotational nonequilibrium effects. The results are compared with experimental results of Chen et al. The fit between the experimental and theoretical results was found to be reasonably good. The results were also compared with those obtained from a model with an equilibrated rotational distribution. It is found that inclusion of a rotational nonequilibrated distribution which decreases the output energy by 25 percent has a certain effect on the output energy distribution among the various vibrational states but is of little importance for the lasing duration.     

超辐射掺铒光纤脉冲放大器的时间特性分析

为了分析掺铒光纤脉冲超辐射放大器的输出特性,通过对时变激光速率方程求解的方法,进行了理论分析和数值验证,获得了系统对不同调制频率的响应和输出特性.结果表明,在一定频率范围内,将产生高峰值超辐射脉冲序列.用0.1W抽运1m铒光纤放大,种子具有纳秒级调制周期且占空比为1/2时,输出脉冲峰值渐减,约200ns后渐趋稳定.通过调节种子信号的光谱特性、调制特性并选择合适的光纤参数,可以控制放大脉冲性质.这一结果为利用超辐射光纤光源产生高功率、光谱性质可调的脉冲提供了有效途径,在1.5μm大气窗口及远程应用中具有实际价值.     

A high-power pulsed xenon ion laser

Over 80 kW of peak power has been obtained on the combined visible lines of a pulsed xenon ion laser. Light pulse shapes of the strongest lines are discussed.