Abstract
Topological photonics, an emerging field in photonics, attracts many researchers not only due to its
fundamental interests, but also due to its potential applications. Introducing the concept of band
topology into photonic systems enables the realization of various topological states of light. Photonic
crystals (PhCs) are an important platform for the study of topological photonics, particular for integrated
photonic circuits. Topologically protected edge states, which function as optical waveguides enabling
robust light transport, have been intensively studied. Meanwhile, optical cavities are another key
component in integrated photonic systems. Here, we will discuss an optical nanocavity realized using
the semiconductor PhC platform. We designed two topologically distinct PhC nanobeams and
experimentally demonstrated lasing oscillation using a topological localized mode at the interface
between them.
