斜入射滤光片的偏振相关损耗抑制技术

Restraining Technology on the Polarization Dependent Loss of the Thin-film Filter in Oblique Incidence

多腔窄带薄膜滤光片在倾斜入射时由于偏振光的中心波长会出现分离,会导致其偏振相关损耗迅速增加,严重影响光通信系统的性能。从理论上分析了斜入射时产生偏振相关损耗的原因,并提出了通过优化膜系的方法有效的实现了偏振光中心波长的对准,有效的降低了其通带内的偏振相关损耗。同时还提出了使用偏振分束器的方法,对单偏振光进行调制,在整个透射带内都实现了对偏振相关损耗的抑制。实验结果表明,两种消偏方式都能将窄带滤光片斜入射时的偏振相关损耗减小至0.2dB内,根据实际需要可以应用于不同的场合。

The central wavelength of the polarization modes will separate obviously when the multiple cavities narrowband thin-film filter is in oblique incidence,which will cause the rapid increasing of the polarization dependent loss. It will seriously affect the optical communication system performance. The reason of the polarization dependent loss in oblique incidence is analyzed theoretically. By optimizing the thin-film stack,the central wavelength of the two polarization modes can be calibrated and the polarization dependent loss in the passband of the filter can be restrained effectively. Meanwhile,by using the polarization beam-splitters,the polarization dependent loss in the whole bandwidth of the filter can be also restrained. The experimental results show that these two methods can restrain the polarization dependent loss of the narrowband filter within 0.2 dB in oblique incidence,and they can be used in different occasion according to different practical demand.