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光参量啁啾脉冲放大器(OPCPA)是现阶段最常用的超短超强脉冲放大器之一。参量荧光是OPCPA的本征量子噪声,其形成的脉冲底座会大大降低输出信号脉冲的信噪比。采用数值模拟的方法,研究了不同脉宽比和抽运波形条件下参量荧光的演化规律及其对信噪比的影响。计算结果表明,在增益一定的情况下,随着脉宽比的增大,信噪比与效率-带宽积都呈先增大后减小的趋势。存在一个最佳脉宽比,使得两者同时达到最大。脉宽比小于此最佳值时,随着超高斯抽运光波形阶数的增大,信噪比减小而效率-带宽积增大;脉宽比大于此最佳值时,随着超高斯抽运光波形阶数的增大,信噪比增大而效率-带宽积减小。
Optical parametric chirp pulse amplifier (OPCPA) is one of the most commonly used ultra-short super pulse amplifiers at this stage. The parametric fluorescence is the intrinsic quantum noise of the OPCPA, and the formation of a pulse pedestal significantly reduces the signal-to-noise ratio of the output signal pulse. The evolution of parametric fluorescence under different pulse width and pumping waveforms and its effect on signal-to-noise ratio were studied by numerical simulation. The results show that the signal-to-noise ratio and efficiency-bandwidth product both increase first and then decrease with the increase of pulse-width ratio under certain gain. There is an optimum pulse width ratio that maximizes both at the same time. When the pulse width ratio is less than this optimal value, the signal-to-noise ratio decreases and the efficiency-bandwidth product increases as the order of the waveform of the super-Gaussian pumping light increases. When the pulse width ratio is larger than this optimal value, Gaussian pumping light waveform order increases, the signal to noise ratio increases and the efficiency - the bandwidth product decreases.