Polarization-Insensitive Filter for Incidence Between Classic and Full Conical Mountings

An angular-dependent polarization-insensitive filter in the telecommunication region is demonstrated in this letter, which is based on a zero-contrast grating for incident plane between classic and full conical mountings. Particle swam optimization combined with the rigorous coupled wave analysis method is applied to design the filter and perform the reflectance spectra. Realization of the polarization-insensitive filter is based on the split feature of a 1D guided mode resonant filter, under oblique incidence in classic mounting. Results show that polarization-independent resonances occur near $1.454~\mu \text{m}$ under the oblique incidences of 4.8°, 5.3°, 6.5°, and 9.3°, with the incident plane angle being set as 15°, 30°, 45°, and 60°, respectively. During the process of varying the incident plane angle from classical mounting to full conical mounting, the mechanism of the increased angle of oblique incidence is also analyzed in detail.