Electrically Tunable Spin‐Orbit Coupled Photonic Lattice in a Liquid Crystal Microcavity

Abstract

A 1D photonic crystal is created with strong polarization dependence and tunable by an applied electric field. This is accomplished in a planar microcavity by embedding a cholesteric liquid crystal (LC), which spontaneously forms a uniform lying helix (ULH). The applied voltage controls the orientation of the LC molecules and, consequently, the strength of a polarization‐dependent periodic potential. It leads to opening or closing of photonic bandgaps in the dispersion of the massive photons in the microcavity. In addition, when the ULH structure possesses a molecular tilt, it induces a spin‐orbit coupling between the lattice bands of different parity. This interband spin‐orbit coupling (ISOC) is analogous to optical activity and can be treated as a synthetic non‐Abelian gauge potential. Finally, it is showed that doping the LC with dyes allows us to achieve lasing that inherits all the above‐mentioned tunable properties of LC microcavity, including dual and circularly‐polarized lasing.