Dependence of the amplifying parameters on buffer gases in copper-vapor lasers

We use a pair of copper-vapor lasers in the oscillator–amplifier configuration for investigating the small-signal gain and the intensity saturation as the amplifying parameters, versus the pressure of various types of buffer gases. We show that the small-signal gain increases and the intensity saturation decreases with increase in the air pressure. Moreover, the values of these parameters are different for various gases used in the amplifier media. We show that both parameters are greater at the atmosphere of neon as a buffer gas than that of a mixture of helium and neon or air.     

Pressure dependence of small signal gain and saturation intensity of a gold-vapor laser using various buffer gases in gain medium

A pair of gold-vapor laser (627.8 nm) in an oscillator-amplifier configuration was used to investigate the small signal gain, g₀, and saturation intensity, I_s, as amplifying parameters, versus pressure at various types of buffer gas. It was shown that the small signal gain decreases and saturation intensity increases linearly with increasing the pressure. Moreover, the values of these parameters are different using various gas mixtures in gain medium. Both parameters were estimated to be more at helium buffer gas atmosphere than that of neon or their mixed ones.     

Pressure Dependence of the Small-Signal Gain and Saturation Intensity of a Copper Bromide Laser

A pair of copper bromide lasers in an oscillator-amplifier configuration is used to investigate the small signal gain and saturation intensity as amplifying parameters and output power of lasers, versus pressure of buffer gas. It is shown that the amplifying parameters and laser output power have a maximum value at optimum buffer gas pressure of 11 Torr. The challenge between microscopic parameters such as stimulated emission cross section, laser upper level lifetime, and population inversion, which determine the values of laser characteristics respective to the operational pressure of buffer gas, are investigated. Thus an optimum delay time of about 10 ns is determined, and a maximum output power equivalent to about 12 W is extracted. The amplifying parameters and measured output power of laser versus delay times show some local maxima and minima at the delay time interval of 6-43 ns.     

INVERSIONLESS GAIN IN A THREE-LEVEL SYSTEM DRIVEN BY A STRONG FIELD AND COLLISIONS

Inversionless gain in a degenerate three-level system driven by a strong external field and by collisions with a buffer gas is investigated. The mechanism of population distribution in upper laser level, contributed by the collision transfer, as well as by relaxation, induced by pressure of a buffer gas, is discussed in detail. Explicit formulae for analysis of optimal conditions are derived. The idea developed here for the incoherent pump could be generalized to other systems.     

气体脉冲放电等离子体阻抗的参量研究

在纯净氦气条件下，对高频纵向脉冲放电的等离子体动态阻抗进行了实验研究.测量了放电等离子体阻抗随放电电压、频率以及气体压强之间的变化关系，表明等离子体阻抗随频率和电压的增加而下降，随气压的升高而增大.定性分析了这些宏观参量与等离子体阻抗变化之间的关系，拟合出等离子体阻抗随电压、频率、气压变化的经验公式，并对数值模拟与实验结果进行了比较研究. 关键词： 等离子体阻抗 气体脉冲放电     

Pressure dependent modulation instability in photonic crystal fiber filled with argon gas

By using the designed photonic crystal fiber filled with argon gas, the effect of gas pressure on modulation instability(MI) gain is analyzed in detail. The MI gain bandwidth increases gradually as the argon gas pressure rises from 1 P_0 to 400 P_0(P_0 is one standard atmosphere), while its gain amplitude slightly decreases. Moreover, the increase of the incident light power also results in the increase of MI gain bandwidth in the Stokes or anti-Stokes region when the incident power increases from 1 W to 200 W. Making use of the optimal parameters including the higher argon gas pressure(400 P_0) and the incident light power(200 W), we finally obtain a 100 nm broadband MI gain. These results indicate that controlling the MI gain characteristic by changing the argon gas pressure in PCF is an effective way when the incident light source is not easy to satisfy the requirement of practical application. This method of controlling MI gain can be used in optical communication and laser shaping.     

Frequency dependence of amplifying parameters of a copper vapor laser using air as a buffer gas

We use a pair of copper vapor lasers in an oscillator–amplifier configuration to investigate amplifying parameters such as the small signal gain and the saturation intensity versus the pulse repetition frequency when two different types of buffer gases are employed. We show that the values of these parameters are not the same if different gas mixtures are used in the gain medium. We show that the values of the parameters are estimated to be higher if a He–Ne buffer gas is used than in the case of air. The laser output power is relatively high and has fairly good stability at some special pulse repetition frequencies when air is used as a buffer gas.     

Lasing on the resonance transition in sodium atoms under nonresonant optical excitation

Coherent emission on the 3P–3S resonance transition (D line) of nonresonantly excited sodium atoms in a buffer gas atmosphere is studied experimentally and theoretically. Both forward and backward coherent emission on the D lines is observed relative to the propagation direction of a pump beam whose frequency is blue-shifted from resonance. The divergence of the emitted radiation does not exceed that of the pump beam. The emission is due to the population inversion created on the “operating” transition when the pump is far detuned from resonance and the buffer gas pressure is sufficiently high. It is found that both emission intensity and the detuning range where this phenomenon is observed increase with the buffer gas pressure.     

激光诱导Al等离子体发射光谱特性的实验研究

本文从实验上研究了不同缓冲气体(He,Ar,N2和Air)中激光Al等离子体的时间分辨发射光谱,研究了原子发射谱线的强度和Stark展宽随延时、缓冲气体性质和压力变化的规律.结果表明原子谱线的强度在3μs左右达到最大值,随着延时的增加,谱线的Stark展宽减小,而缓冲气体压力的增大导致谱线的Stark展宽增大,在实验测定的四种缓冲气体中,Ar气体中谱线的Stark展宽最大.     

High buffer gas pressure perturbation of coherent population trapping in sodium vapors

We report an experimental investigation of coherent population trapping in specially selected Zeeman levels of the sodium atom, performed under high buffer gas pressure in a polydimethylsiloxane coated cell at room temperature. The results show that coherent population trapping will not be completely destroyed when the buffer gas pressure reaches 1100 Torr for He and 1000, 800, and 500 Torr, for Ne, Ar and Kr, respectively. Buffer gases with heavier mass play a larger destructive role for the coherent population trapping. The line width of the dark resonance is reduced with buffer gas pressure. The behavior of the dark resonances on increasing buffer gas is discussed and possible applications are pointed out.