Single line high efficiency tunable fir generation by resonant four-wave mixing in CH3 pumped by a multiatmosphere tunable CO2 laser

By pumping CH₃F with a high pressure tunable TE-CO₂ laser, the resonant four-wave mixing process (RFWM) generates a very efficient tunable single line FIR emission at the Raman frequency. This result is strictly related to the spectroscopic structure of the CH₃F molecule. By means of this process, a tunable FIR emission on a 0.1 cm^–1 bandwidth 150 kW (8 mJ) single line, is obtained which can be used for many FIR multiphoton applications.     

A technique for the alignment of a ring laser cavity

An alignment technique for a ring laser cavity is presented which is suitable for a resonator into which auxillary laser beams cannot pass.     

Development and application of the Fraunhofer-diffraction method for measurements of plasma density fluctuations using infrared lasers

This paper is concerned with systematic developments of the Fraunhofer-diffraction method for studies of plasma density fluctuations in high-temperature plasmas using infrared lasers, namely (i) development of the general theory of the Fraunhofer-diffraction method, (ii) measurements of fluctuations propagating in an azimuthal direction, (iii) measurements of fluctuation intensities, and (iv) application in measurements on high-temperature plasmas.     

Relativistic electron motion in FEL-like fields taking retarded interactions into account

Summary The interaction of two charged particles both with each other (via Lienard-Wiechert retarded potentials) and with the wiggler field of an FEL structure, along which they are launched, is computed by means of the numerical integration of the relativistic motion equations, taking also an incoming laser wave into account. The bunching effect characterizing the collective behaviour of an electron beam in FEL-like fields is simulated by assuming one of the particles to be a suitable macrocharge.     

Investigation of a Cr: YAG passive Q-switch in CW pumped Nd: YAG lasers

This work describes the experimental results obtained on the Cr⁴⁺:YAG crystal used as a passive Q-switch in Nd: YAG lasers. In addition, the combination of a Cr⁴⁺: YAG passive Q-switch with an acousto-optical Q-switch operating simultaneously in one cavity was investigated. More than 180 W average output in the passive Q-switched mode was obtained with the C⁴⁺: YAG crystal. The pulse-to-pulse stability was better than 1%. A mode selection occurred when the laser system operated near threshold.     

激光二极管端面泵浦的单频固体激光器的理论研究

给出了激光二极管端面泵浦的驻波激光器单频运转时的最大泵浦功率与腔参数和激光介质参烽之间的简单函数关系，对于单频激光器的设计具有实际指导意义。     

Suppression of dynamic instability and comparison of the response time in mutually pumped phase conjugators

The origin and the suppression of dynamic instability have been experimentally studied in mutually pumped phase conjugators when the two input beams are coherent. Experimental results show that the dynamic instability of the phase conjugation outputs arises from the competition among backscattering gratings, reflection gratings, and shared transmission gratings. The effect of the competition on the coupling channel is also presented. A simple method, the slight vibration of the experimental table is proposed. It can eliminate the dynamic instability. The response time is measured and fit for several kinds of discovered mutually pumped phase conjugators. We find that the bird-wing and sickle mutually pumped phase conjugators, which have one internal reflection, have a shorter response time. A possible explanation is suggested.     

Influence of Nonlinear Gain and Nonradiative Recombination on the Quantum Noise in InGaAsP Semiconductor Lasers

Effects of nonlinear gain and nonradiative recombination on characteristics of intensity and phase noises of InGaAsP lasers emitting in a wavelength of 1.55 Μm are investigated. The investigations are performed based on a self consistent numerical approach that takes into account the cross correlation of fluctuations among the injected electron number, photon number and the optical phase. Time variations of the fluctuations of the intensity and the shift of the lasing frequency are statistically analyzed. The corresponding frequency dependencies of intensity and frequency noises are characterized. The results show that both intensity and frequency noises around the relaxation frequency are suppressed when counting the nonlinear gain in the rate equations. The intensity noise is enhanced in the low frequency regime by increasing the nonradiative recombination. The results fit well with those predicted by the small-signal analysis.     

基于泛函连接神经网络的FIR滤波器设计方法

基于4种FIR线性相位滤波器幅频响应函数的统一表示形式,提出了一种泛函连接神经网络模型,并应用于线性相位FIR滤波器的设计.该网络模型在实际应用中保持了余弦神经网络模型的一切优点,并且能够设计出余弦神经网络不能够设计出的单位冲激响应为奇对称的FIR线性相位滤波器,该神经网络模型具有较强的泛化能力.多通带滤波器和90°移相器两种FIR线性相位滤波器的设计实例,表明了该网络模型在高阶线性相位FIR滤波器设计中的有效性和优越性.