Fabry-Perot Bound States in the Continuum in an Anisotropic Photonic Crystal

An anisotropic photonic crystal containing two anisotropic defect layers is considered. It is demonstrated that the system under can support a Fabry-Perot bound state in the continuum (FP-BIC). A fully analytic solution of the scattering problem as well as a condition for FP-BIC have been derived in the framework of the temporal coupled-mode theory

Chiral Optical Tamm States at the Interface between a Cholesteric and an All-Dielectric Polarization-Preserving Anisotropic Mirror

The chiral optical Tamm state is a new localized state of light at the interface between a polarization-preserving anisotropic mirror and an optically chiral medium such as a cholesteric liquid crystal. In this study the metal-free polarization-preserving mirror is used for efficient resonance control. We stress the advantage of the all-dielectric structure in obtaining high Q factor. The light is localized near the interface and the field decreases exponentially with the distance from the interface. The penetration of the field into the chiral medium is virtually blocked at wavelengths corresponding to the photonic band gap and close to the pitch of the helix. The polarization-preserving mirror has another photonic band gap as well. Our analytics agrees well with precise calculations, enabling intelligent design for laser and sensing applications.Comment: in Russia

Enhanced light absorption in Tamm metasurface with a bound state in the continuum

We consider light absorption in a germanium grating placed on top of photonic-crystalline substrate. Such a system supports an optical Tamm state decoupled from the continuous spectrum with its frequency within the photonic band gap. We have demonstrated that application of the Tamm state makes in possible to engineer extremely narrow absorber which provides a 100% absorption in a semiconductor grating in the critical coupling regime. The proposed design may be used at both normal and oblique incidence at the telecom wavelength