Coupled Chiral Optical Tamm States in Cholesteric Liquid Crystals

Abstract

The modes formed by two coupled chiral optical Tamm states localized at the interfaces between a photonic cholesteric liquid crystal conjugated with polarization-preserving anisotropic mirrors have been analytically and numerically investigated. These modes are only excited at the diffracting polarization of incident light. As the cholesteric layer thickness decreases, the spectral splitting of the localized state frequency is predicted. The splitting value depends on the crystal layer thickness. At the nondiffracting circular polarization, the localized modes are not excited, and the system becomes similar to the Fabry–Pérot cavity containing an anisotropic helical structure.

Model of a tunable hybrid Tamm mode–liquid crystal device

“…The frequency of the COTS localized at the interface between two media with reflectivities rPPAM and rCLC and the angle φ between the optical axes can be found similarly from the equation [30] rPPAMrCLCe 2iφ =1, ( 7) where rPPAM and rCLC are the PPAM and CLC amplitude reflectivities and φ is the angle between the CLC optical axis and the mirror layer adjacent to it.…”

“…Therefore, it is difficult to observe the Tamm modes localized between a CLC and a metallic layer [13,26,27]. A possible way of observing them is to use of a polarization preserving (handedness preserving or chiral) anisotropic mirror (PPAM) [28][29][30].…”

Chiral Optical Tamm States at the Interface between a Dye-Doped Cholesteric Liquid Crystal and an Anisotropic Mirror

“…A special class is the equichiral Reusch piles, in which the optical axes of neighboring layers become perpendicular to each other [ 29 ]. Previously, we demonstrated the possibility of implementing the OTS at the interface between a PPAM and a CLC; the obtained localized surface state was called the chiral optical Tamm state (COTS) [ 23 , 24 , 30 , 31 ].…”