Radiative-channel valley topological laser

TL;DR

This paper demonstrates room-temperature topological lasing in a valley photonic crystal, highlighting how radiative losses can be harnessed to control lasing pathways and achieve single-mode operation.

Contribution

It experimentally shows radiative-channel-driven topological lasing in a nanorod-based photonic crystal, emphasizing the role of loss channels in lasing physics.

Findings

Achieved single-mode topological lasing at room temperature.

Loss mechanisms can be exploited to establish lasing pathways.

Identified a narrow spectral window where gain-loss balance supports lasing.

Abstract

Active topological photonic systems enable robust light control and new pathways for semiconductor lasing. However, their intrinsically non-Hermitian nature, combining gain, radiation leakage, and material loss, makes the underlying physics more complex, and prior studies have mostly focused on gain competition while the influence of loss channels is less examined. Here, we experimentally demonstrate radiative-channel-driven topological lasing in a valley photonic crystal consisting of isolated InP nanorods on an insulator, achieving room-temperature single-mode operation within an about 4 lambda scale cavity. Loss-included simulations show that material absorption and radiative leakage can be exploited to establish the lasing pathway. Local off-edge pumping provides spatial evidence of topological edge-guided lasing. Berry-curvature calculations, reflecting unit-cell symmetry breaking, verify the valley-Hall interface in a triangular lattice. Geometry and temperature tuning identify a narrow spectral window where the above-light-line edge branch matches the gain-loss balance and remains decoupled from bulk bands. These results clarify how the loss landscape governs topological lasing and establish a radiative-edge design framework for active topological photonics. The substrate-supported nanorod architecture additionally offers a scalable route for on-chip implementation.