角度调谐滤光片特性分析及膜系设计

对窄带滤光片的倾斜入射特性作了分析.斜入射时其透射通带和峰值会向短波方向移动,透射曲线的稳定性跟滤光片的间隔层结构相关,多腔间使用相同的间隔层可以保证斜入射时有稳定的峰值透射率和带宽,利用该特点可以制备角度调谐窄带滤光片.透射光S和P偏振分量的中心波长随入射角度的增大出现分离现象,产生较大的偏振相关损耗.通过搭配不同厚度的高低折射率材料作为间隔层,改变其有效折射率,使其两个偏振分量的中心波长实现重合.设计了符合密集波分复用(Dense Wavelength Division Multiplexing,DWDM)系统要求的低偏振相关损耗四腔窄带角度调谐滤光片膜系,其可调谐范围达20 nm以上,并评估了所设计角度调谐滤光片的调谐性能.

Characteristics Analysis and Stack Design of Angle-tuned Filter

The characteristics of the thin film narrowband filters used in tilted incidence are analyzed.Its transmission peak and bandwidth will shift to shorter wavelength and its transmission stability relies on the structure of the spacer.Using the spacers of the same structure between the cavities,the filter have a stable transmission peak and bandwidth when it is used in tilted incidence.It can design angle-tuned narrowband filters through the characteristic.The central wavelength of S-polarization and P-polarization will separate when the filter is tilted.It causes the Polarization Dependent Loss.Using different thickness of the high and low index materials for spacer,the central wavelength of the two polarization can be coincided because the effective refractive index is changed.The stack of four-cavities angle-tuned narrowband filters with low Polarization Dependent Loss is designed and its tunable range is over 20 nm.The tunable performance of the different stacks is evaluated.