Localised states with Rashba-Dresselhaus spin-orbit coupling

Abstract

The ability to precisely tune individual coupling amplitudes in photonic lattices is highly desirable for developing optical communication systems and enhancing the performance of photonic integrated circuits. Recently, a novel form of photonic spin-orbit coupling known as Rashba-Dresselhaus spin-orbit coupling (RDSOC) has been developed in highly birefringent optical microcavities [1]. This new coupling mechanism emerges from the interaction between modes of orthogonal polarization and opposite parity. In recent studies, many interesting phenomena such as persistent spin helix [2], polariton lasing [3], spin Hall effect [4], and polariton striped phase [5] were reported for planar liquid crystal cavities. However, localized states in liquid crystal microcavity showing RDSOC have not yet been investigated. Here, we investigate localised states in the presence of RDSOC. By utilizing a patterned microcavity filled with highly birefringent liquid crystals, we demonstrate experimentally in situ tunability of tunneling between lattice sites via RDSOC in optical microcavities. We focus on single and double Gaussian traps fabricated by Focused Ion Beam milling. The control of tunneling between the Gaussian traps is realized by applying an external voltage to the microcavity. Our method utilizes the gauge field, i.e. RDSOC, to achieve the tunneling control, contrary to the generally inverse approach. We demonstrate a topological transition being a result of tunneling sign inversion. Finally, strong coupling in liquid crystal cavities together with polariton condensation and its potential behavior in the presence of localized states is discussed. Our purely photonic realization can be extended and used as a new platform for light-matter coupling, topological photonics, and nonlinear physics.