Tunable Frequency Filter Based on Twisted Bilayer Photonic Crystal Slabs
Beicheng Lou, Shanhui Fan
Abstract
We introduce a tunable narrow-band-stop frequency filter based on twisted bilayer photonic crystal slabs. The operation of the filter is based on the guided resonance of the slabs. We choose to operate in a regime where the operating wavelength is significantly larger than the periodicity of the individual photonic crystal slabs, such that all the resonances in the operating frequency range arise from the Moire periodicity, and hence, their resonant frequencies are strongly dependent upon the twist angle. We also show that a desired notch filter line shape can be achieved by introducing additional uniform slabs and that the filter can operate without diffraction loss and is polarization-independent. Such a filter may be potentially important for communication and signal processing applications.