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

Abstract

As a new localized state of light, the chiral optical Tamm state exists at the interface between a polarization-retaining anisotropic mirror and a substance with optical activity. Considering a hybrid structure comprising a metal-free polarization-preserving mirror and a cholesteric liquid crystal, we highlight the high Q factor arising from the all-dielectric framework. The intensity of localized light decreases exponentially with increasing distance from the interface. The penetration of the field into the cholesteric liquid crystal is essentially prohibited for wavelengths lying in the photonic bandgap and close to the cholesteric pitch length. The dielectric mirror has its own photonic bandgap. The energy transfer along the interface can be effectively switched off by setting the tangential wave vector to zero. The spectral behavior of the chiral optical Tamm state is observed both as reflection and transmission resonance. This Fano resonance is analogous to the Kopp-Genack effect. Our analytics are well in line with precise calculations, which may pave a new route for the future development of intelligent design for laser and sensing applications.

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

“…The fulfillment of this condition ensures the excitation of a localized state at the diffracting polarization at a wavelength of nm, while at the polarization of the opposite sign (nondiffracting polarization), the COTS is not excited. The observed state is high- Q and can be effectively tuned in frequency [ 30 ].…”

“…The layers are virtually quarter-vawelength. The multiple layer boundaries correspond to standing wave nodes and antinodes of x and y components of electric field [ 30 ], that results in rippling of the overall field. Second, the local intensity rippling in CLC has different origin, because the CLC material is homogeneously twisted along z direction and its main eigenwave is a smoothly evanescenting exponential [ 20 ].…”

“…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 ].…”

Chiral-Selective Tamm Plasmon Polaritons

“…The phase matching is another crucial condition for localized state excitation. This second condition is equivalent to the geometric phase condition for the angle between the long axis of the metasurface nanobrick and the CLC direction [ 31 , 32 ]. In Figure 2 b, this angle is shown to be and the TPP resonance frequency approximately corresponds to the center of the CLC stopband.…”

Coupled Chiral Optical Tamm States in Cholesteric Liquid Crystals

“…This is a necessary condition for forming the OTS at the CLC boundary. In [28], a chiral OTS was described at the CLC and PPAM interface. The angles between the CLC optical axes and adjacent mirror layers are hereinafter referred to as ψ and ϕ, respectively.…”