Spontaneous mirror-symmetry breaking in coupled photonic-crystal nanolasers

Abstract

Multi-cavity photonic systems, also known as photonic molecules, exhibit multi-well potentials that may prove useful for advanced quantum and nonlinear optics. A key phenomenon arising in double-well potentials is the spontaneous breaking of inversion symmetry, with a transition to two localized states in the wells, which are mirror images of each other. Although a few theoretical studies have addressed mirror-symmetry breaking in micro- and nanophotonic systems, no experimental evidence has been reported to date. Here, we demonstrate spontaneous mirror-symmetry breaking through a pitchfork bifurcation in a photonic molecule composed of two coupled photonic-crystal nanolasers. The coexistence of localized states is shown by switching them with short pulses. This offers exciting prospects for the realization of ultra-compact, integrated, scalable optical flip-flops. Analysis suggests that such symmetry breaking should be possible with a small number of intracavity photons and is thus suitable for quantum correlation devices.