提升啁啾脉冲激光信噪比的扫描滤波方法

摘要

Based on the principle of scanning filtering,a new optical scanning filtering method for improving signal-to-noise ratio（SNR） of the chirped pulse is proposed.For the scanning filtering scheme of Fabry-Perot（F-P） etalon including an electro-optic crystal,the spectral characteristics of the scanning filter are analyzed quantitatively.Furthermore,the effects of the reflectivity of the parallel-plates of F-P etalon and the types of the electro-optic crystals on the output SNR are discussed in detail,and the influence of the variation of the controlling voltage applied to the electro-optic crystal on the filtering effect is also studied.The results show that the narrower the bandwidth of scanning filter transmission window is,the better the improved SNR will be.In order to ensure the filtering effect,the reflectivity of the parallel-plates of F-P etalon should be more than 0.9.Compared with the scheme of scanning filter built-in ordinary linear electro-optic crystal,the scheme of F-P etalon including an secondary standard electro-optic crystal,i.e.,KTa1-xNbx O3 crystal, requires a low voltage,and it is easy to control.The differences of KTa1-xNbx O3 crystal components have little influence on the filtering effect,whereas the variations of controlling voltage and chirp rate of the signal exhibit a greater influence on the filtering effect.%基于扫描滤波原理,提出了一种新的用以提升啁啾脉冲激光信噪比（signal-to-noise,SNR）的光学扫描滤波方法.针对内置电光晶体的Fabry-Perot标准具的扫描滤波方案,定量分析了其扫描滤波谱特性,详细讨论了Fabry-Perot标准具平行平板的镜面反射率和内置电光晶体类型对输出脉冲信噪比的影响,并进一步探讨了控制电压变化对信噪比提升效果的影响.结果表明,扫描滤波器的透射窗口带宽越窄,信噪比的提升效果越好;为了保证输出效果,Fabry-Perot标准具平行平板反射率应大于0.9;对于内置二次电光晶体钽铌酸钾晶体的Fabry-Perot标准具扫描滤波方案,其外加电压较内置普通线性电光晶体的方案更低,且更易于控制;钽铌酸钾晶体构成组分的不同对滤波器效果的影响并不大,而控制电压和信号光啁啾率的变化则会对滤波效果产生较大影响.