非均匀加宽系统中宽带激光脉冲的增益特性研究

Study on the Gain Property of Broadband Laser Pulse in the Inhomogeneously Broadening System

基于线性啁啾脉冲的特性,建立了一种描述非均匀加宽系统中宽带啁啾激光脉冲放大的理论计算模型。这种模型的基本思想是,将啁啾脉冲看成是由一系列时间上依次排列的准单色子脉冲所组成,利用已有的Frantz-Nodvik模型计算非均匀加宽系统中的脉冲放大特性。数值计算结果表明:尽管与均匀加宽系统一样,非均匀加宽系统中也存在增益变窄和脉冲畸变效应,但在非均匀加宽系统中,脉冲前沿和后沿获得同样的放大,输出脉冲频谱也相对于中心频率对称。此外,输入脉冲的带宽越大,增益变窄和脉冲畸变效应越显著,且输出脉冲的波形逐渐向线型函数的形状过渡。

Based on the characteristics of linearly chirped pulse, a numerical model for amplification of broadband chirped pulse in the inhomogeneous broadening system has been established. The basic idea of this model is that the input chirped pulses are considered to consist of many quasi monochromatic pulses having different center frequencies and intensities, thus using the Frantz-Nodvik model the amplification is calculated. Numerical simulations indicate that the inhomogeneous broadening system astmell as the homogeneous one has the effects of gain narrowing and pulse distortion, however, in the output pulse of the inhomogeneous broadening system, the leading edge will undergo the same amplification as the trailing edge, and the spectrum is symmetrical to the center frequency. In addition, while the spectral bandwidth of the input pulse increasing, both gain narrowing and pulse distortion are becoming more serious, and the profile of output pulse is growing more similar in shape to the lineshape of the inhomogeneous broadening system.