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在时间-频率域中,啁啾脉冲被淹没在放大自发辐射等噪声中,且其瞬时频率线性分布,基于此,提出采用光谱扫描滤波的办法来提升高功率飞秒激光系统的信噪比,并以法布里-珀罗干涉仪作为光谱扫描滤波器,对该法提升信噪比的效果进行了详细的理论分析.采用短时傅里叶变换方法,研究了光谱扫描滤波器对自发辐射放大(ASE)的滤波效果,数值分析表明,在时间抖动为-2 ps到2 ps之间、光谱扫描滤波器的通带宽度为0.4 nm条件下,该法能将飞秒激光系统的信噪比提升2个量级,而啁啾信号光以超过90%的透光率通过光谱扫描滤波器;级联光谱扫描滤波方式能进一步提升飞秒激光信噪比.
In the time-frequency domain, the chirped pulse is submerged in the noise such as amplified spontaneous emission, and the instantaneous frequency of the chirped pulse is linearly distributed. Based on this, the spectral scanning filter is proposed to improve the signal-noise ratio of the high-power femtosecond laser system, And Fabry-Perot interferometer as a spectral scanning filter, the method to enhance the effect of signal to noise ratio in detail a theoretical analysis.Using short-time Fourier transform method, the spectral scanning filter for spontaneous emission (ASE). The numerical analysis shows that the signal-to-noise of the femtosecond laser system can be obtained under the condition of time jitter of -2 ps to 2 ps and spectral pass filter of 0.4 nm. Ratio is improved by two orders of magnitude, while the chirp signal light passes the spectral scanning filter with more than 90% transmittance; and the tandem spectral scanning filtering method can further improve the signal-to-noise ratio of the femtosecond laser.