利用真空溅射法在一片亚毫米尺度的光学玻璃平板两面分别镀上不同厚度的金属薄膜,构成一种超厚的双面金属包覆波导。采用自由空间耦合技术实现了这种波导中超高阶导模的激发。由于超高阶导模具有对波长特别灵敏而对偏振不灵敏的特殊性质,以此为基础,在实验中演示了可调谐、偏振不灵敏、低损耗(小于0.5 dB)的超窄带(小于0.08 nm)和梳状滤波(通道间隔为100 GHz)。 Using vacuum sputtering method, a thin metal film with different thicknesses is respectively coated on two sides of a sub-millimeter-scale optical glass plate to form an ultra-thick double-sided metal clad waveguide. Excitation of ultrahigh-order guided modes in this waveguide is achieved using free space coupling. Due to the special properties of ultra-high-order guided modes that are wavelength-insensitive and polarization-insensitive, based on this, we demonstrate in our experiments tunable, polarization-insensitive, ultra-narrowband with low loss (less than 0.5 dB) (less than 0.08 nm) and comb filtering (channel spacing of 100 GHz).