Tunable multi-channel optical filters based on Octonacci one-dimensional photonic quasicrystals

Abstract

We propose a structure for a tunable multi-channel optical filter based on a one-dimensional quasicrystal made up of ZnSe (layer H) and ZnS (layer L) layers organized following the Octonacci sequence. The fourth stage of the sequence, S4, is considered here with initial conditions S1 = L and S2 = H giving the multi-layered system a structure of HLHHHLH. The transmittance spectrum of the s-polarized (transverse electric mode) light is obtained analytically by employing a theoretical calculation based on the transfer matrix method. For normally incident waves, four output signals are transmitted out from the structure. The transmitted signals move to shorter wavelengths as the angle of incidence increases up to 89 deg. At this angle of incidence, the output signals exhibit narrow, sharp, and well-defined resonant peaks. On the other hand, the resonant peaks shift to longer wavelengths as the ambient temperature increases from room temperature to 500°C. The obtained results reveal that the proposed structure could be used as an efficient multi-channel optical filter. The overall dimension of the proposed structure is about 569 nm, which practically makes the filter easily integrated into photonic circuits.