Electrically tunable spin-orbit coupled photonic lattice in a liquid crystal microcavity

TL;DR

This paper demonstrates a tunable one-dimensional photonic crystal in a liquid crystal microcavity, exhibiting controllable band gaps, spin-orbit coupling, and polarized lasing through electric field manipulation.

Contribution

It introduces a novel electrically tunable photonic lattice with spin-orbit coupling effects in a liquid crystal microcavity, enabling dynamic control of photonic properties.

Findings

Electric field controls polarization-dependent band gaps.

Induction of spin-orbit coupling via molecular tilt.

Dye doping enables polarized lasing with tunable properties.

Abstract

We create a one-dimensional photonic crystal with strong polarization dependence and tunable by an applied electric field. We accomplish this 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 band gaps 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, we show 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.