为了解决环形激光器小型化中信号信噪比随腔长减小而下降的问题,设计了一种能压制He-Ne气体放电辉光而不影响激光光强的窄带滤光片.基于OpenFilters软件独有的“step”自动膜系设计方法,以初始膜层厚度为线索,设计了符合光谱特性实际应用要求的多个非规整膜系结构.考虑膜层数、膜层厚度及应力等因素,选出便于石英晶振监控的窄带滤光片.在45°的入射角下,该滤光片对s偏振光在632.8nm处的峰值透射率为99.9%,通带半峰值全宽为5.2nm,截止带平均透射率为1.35%.结果表明,该滤光片可有效压制He-Ne气体的放电辉光,提高小型环形激光器的信噪比.

In order to solve the problem of signal-to-noise ratio decreasing with the decreasing of cavity length during the miniaturization of ring laser,narrow band filter was designed for suppressing the discharge glow of He-Ne gas without affecting on laser output.Based the unique “step” automatic coating design method of OpenFilters software and using the initial film thickness as the clue,a number of non-structured membrane structures were designed for the requirements of practical application of spectral characteristics.An optimized narrow band filter for crystal monitoring was selected under the consideration of layer number,thickness and stress.When s polarization light was incident from the air at angle of 45°,the filter had peak transmittance of 99.9% at central wavelength of 632.8nm,full width at half maximum of 5.2nm and average transmittance at cutoff band of 1.35%.The results show that the filter can suppress the discharge glow of He-Ne gas effectively and improve the signal-to-noise ratio of miniaturized ring laser.