Magnetic-spiker excitation of gas-discharge lasers

A review is presented on the use of magnetic-spiker circuits to electrically excite rare-gas-halide and CO₂ gas-discharge lasers. The design and operation of the diode, switch, overshoot, and charge modes of magnetic-spiker excitation will be described. Special emphasis has been placed upon understanding the dynamical behaviour and saturation properties of the magnetic core material at high frequencies. The effect of voltage risetime, preionization, pulse-forming network design, and prefire on laser performance is also described. Experimental data are presented on a new and very simple magnetic-spiker circuit called the modified overshoot mode. A relatively long optical pulse magnetic-spiker KrF laser is also desribed which uses self-timed corona preionization initiated by the spiker circuit. The use of magnetic-spiker excitation to produce high output laser energies, high repetition rates, and long optical pulses is discussed. Applications of magnetic-spiker lasers in the field of medicine, microelectronics and materials processing will be reviewed.     

改进的测二极管伏安特性的电路

指出了某普通物理实验教材中所给出的伏安法测二极管特性的电路所存在的总理２,并 合理的电路。     

伏安特性实验中电压表的改进应用

改进了传统电压表的面板设计,使电压表不仅能测两端的电压,还能测量自身的电流.于是在测量元件的伏安特性实验中,使用该电压表可以不考虑被测器件电阻的大小,均采用电流表外接的接线方式,即让电压表分流.再利用电压表的电流测量功能,测出自身分流电流的大小,从而可以准确得出被测器件的电流与两端的电压.     

Temperature range and conditions of stable operation of gas-discharge rare-earth metal vapor lasers

We have experimentally studied the temperature range and conditions of the stable operation of rare-earth metal (REM) vapor lasers. Gas-discharge tubes made of alumina (Al₂O₃-GDTs) were used in the experiments. The lasing appears at the temperature when the saturated-vapor pressure of REMs reaches the value of 0.1 Torr and abruptly drops at the melting temperature of corresponding REM under any excitation conditions. The necessity of protecting film of REM aluminates Ln_nAl_mO_k and oxides Ln₂O₃ on the inner surface of Al₂O₃-GDT for stable operation of these lasers is shown. An explanation of lasing impossibility in vapors of cerium (Ce), praseodymium (Pr), neodymium (Nd), gadolinium (Gd), and terbium (Tb) under gas-discharge excitation is proposed. PACS  42.55.Lt; 34.10.+x     

The inertia of an S-shaped volt-ampere characteristic and the self-oscillation frequency limits in multilayered heterostructures

Radiophysics and Quantum Electronics -     

The volt-ampere characteristic of a metal-semiconductor junction of small area,with the assumptions of diffusion theory

A metal-semiconductor junction was considered on the assumptions of diffusion theory, taking into account the presence of a gap between the metal and the semiconductor. A junction was chosen of area small enough for it to be possible to neglect the decrease due to recombination relative to the decrease due to divergence of the lines of flow. The volt-ampere characteristics and dependences of the injection coefficient on the voltage were obtained for the cases of low and high injection levels and slight or considerable band bending. It was shown that in all the cases indicated the nature of the dependence of the injection coefficient on the voltage (increasing or decreasing) depends essentially on the distribution of the voltage drop between the gap and the space charge region. Given certain relationships between the parameters of the semiconductor the latter dependence can take the form of a curve with a maximum.     

Investigation of the aging of gas-discharge detectors of particles with the use of nuclear reaction analysis

This paper reports on the results of an investigation into the aging of drift tubes with anodes fabricated from gold-plated tungsten wires under continuous irradiation with a ⁹⁰Sr beta source. The accumulated charge is as high as 9 C cm^?1. The process of aging is studied in a gaseous mixture containing Ar, CO₂, and CF₄. It is revealed that the aging brings about a severe damage of the gold coating on a tungsten wire and an increase in the diameter of the wire in the irradiated zone from 35 to 42 μm. The observed swelling of the anode wire under forces applied from the inside is apparently a new mechanism of aging of anode wires. The swelling effect is assumed to be caused by the oxidation of the tungsten wire. It is demonstrated using the nuclear reaction analysis that the deposits containing tungsten, oxygen, carbon, and fluorine are distributed along the anode wire in the direction of the gas flow. The oxygen and fluorine distributions over the depth and along the length of the anode wire are determined.     

改善外腔半导体激光器调谐特性的新方法

基于原有的Littman结构外腔半导体激光器,提出采用一种新的光学方法来实现波长调谐。该方法采用了包含一个旋转楔形棱镜的“光杠杆”系统来降低调谐的机械要求,提高波长选择精度。通过选择不同的楔形棱镜顶角和光线入射角,机械要求可以降低1～2个数量级,波长选择精度也得到相同量级的提高。该方法使Littman结构外腔半导体激光器的调谐特性得到极大的改善,并大大降低了震动的敏感性。     

Investigation of electron-beam-excited molecular gas lasers

Physical processes are investigated in active media of high-pressure gas lasers operating on electronic transitions of molecules. Lasing was obtained in the VUV ( = 172 nm) region of the spectrum by exciting compressed xenon and an Ar:Xe mixture. The effect of the temperature and pressure on the kinetics of the processes in the active laser media Ar:N₂, Xe:0₂, and Ar:Kr:F₂ are investigated. A new class of excimers, consisting of one halide and two inert atoms, is observed for the first time ever, and the temperature dependence of the spontaneous and laser emissions of XrF* is investigated; this dependence is due to the redistribution of the energy drawn from the electron beam among the excimers KrF^* and Kr2^F*.Translated from Trudy Ordena Lenina Fizicheskogo Instituta im. P. N. Lebedeva, Vol. 142, pp. 172–202, 1983.     

一维随机激光器中准态模的饱和特性研究

针对随机激光器的半经典理论是应用电磁场时域有限差分法数值求解半经典随机激光模型方程组，基于半经典理论数值研究了一维随机激光器中准态模式的饱和特性，获得了不同准态模的空间分布和频谱分布图。计算结果分析显示：准态模式的某些特征参数如局域程度将会影响系统的饱和特性。利用这一结果，可以通过单频抽运方法选择具有低阈值、高饱和强度的准态模式作为整个激光系统的稳态输出模式。     

Investigation polarization characteristics of vertical-cavity surface-emitting lasers

We have improved transmission line laser model to study the polarization characteristics by incorporating into spin-flip model (SFM). Theoretical studies on the influence of the Bragg reflectivity on the polarization switching of vertical-cavity surface-emitting laser (VCSEL) have been discussed in this paper. We have demonstrated that reflectivity of Bragg reflectors can be optimized to provide suitable hysteresis loops width which indicates the tolerance of the input power.     

Investigation of chaos synchronization in photonic crystal lasers

Chaotic dynamics and chaos synchronization in photonic crystal (PC) lasers with optical feedback are investigated numerically. The effect of various system parameters such as amplitude reflectivity of the external mirror “r”, external cavity length “L_e”, and injection current “I” on system dynamics is addressed in detail. Simulation results are presented using MATLAB to address system behavior. The parameters r, L_e, and I are varied over the ranges (0.05–0.25), (2.8–3.2 mm), and (1.1I_th–2I_th), respectively. The results indicate that very small parameter mismatches between the transmitter laser and receiver laser affect strongly complete chaos synchronization between them.     

Investigation of polarisation effects in injection locked lasers

Received: 14 June 1996/Revised version: 6 November 1996