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.