Optical vortex Brillouin laser

TL;DR

This paper demonstrates stable optical vortex oscillations in a Brillouin laser using chiral photonic crystal fiber, enabling narrow linewidth vortex emission with potential applications in quantum information and nonreciprocal systems.

Contribution

It introduces a novel Brillouin laser system supporting vortex-carrying modes with stable oscillation and high spectral resolution, advancing vortex-based photonic technologies.

Findings

Stable vortex oscillation in Brillouin laser achieved.

Narrow linewidth of 10 kHz with 520 kHz accuracy measured.

Supports first- and second-order vortex modes.

Abstract

Optical vortices, which have been extensively studied over the last decades, offer an additional degree of freedom useful in many applications, such as optical tweezers and quantum control. Stimulated Brillouin scattering, providing a narrow linewidth and a strong nonlinear response, has been used to realise quasi-continuous wave (CW) lasers. Here, we report stable oscillation of optical vortices and acoustic modes in a Brillouin laser based on chiral photonic crystal fibre, which robustly supports helical Bloch modes (HBMs) that carry circularly-polarized optical vortex and display circular birefringence. We implement a narrow-linewidth Brillouin fibre laser that stably emits 1st- and 2nd-order vortex-carrying HBMs. Angular momentum conservation selection rules dictate that pump and backward Brillouin signals have opposite topological charge and spin. Additionally, we show that when the chiral PCF is placed within a laser ring cavity, the linewidth-narrowing associated with lasing permits the peak of the Brillouin gain that corresponds to acoustic mode to be measured with resolution of 10 kHz and accuracy of 520 kHz. The results pave the way to a new generation of vortex-carrying SBS systems with applications in quantum information processing, vortex-carrying nonreciprocal systems.