Non-Reciprocal Brillouin Scattering Induced Transparency

TL;DR

This paper introduces a novel non-reciprocal transparency effect called Brillouin scattering induced transparency (BSIT), enabling slow light in silica microresonators through long-lived phonons, overcoming previous coherence limitations.

Contribution

The work demonstrates for the first time that BSIT can be achieved with long-lived phonons, leading to non-reciprocal slow light in microresonators, a significant advancement over prior SBS-based methods.

Findings

BSIT is non-reciprocal due to propagating phonons.

BSIT enables ultralow-power slow light with high delay-bandwidth.

Experimental demonstration in silica microresonators confirms the phenomenon.

Abstract

Electromagnetically induced transparency (EIT) provides a powerful mechanism for controlling light propagation in a dielectric medium, and for producing slow and fast light. EIT traditionally arises from destructive interference induced by a nonradiative coherence in an atomic system. Stimulated Brillouin scattering (SBS) of light from propagating hypersonic acoustic waves has also been used successfully for the generation of slow and fast light. However, EIT-type processes based on SBS were considered infeasible because of the short coherence lifetime of hypersonic phonons. Here, we report a new Brillouin scattering induced transparency (BSIT) phenomenon generated by acousto-optic interaction of light with long-lived propagating phonons. We demonstrate that BSIT is uniquely non-reciprocal due to the propagating acoustic phonon wave and accompanying momentum conservation requirement. Using a silica microresonator having naturally occurring forward-SBS phase-matched modal configuration, we show that BSIT enables compact and ultralow-power slow-light generation with delay-bandwidth product comparable to state-of-the-art SBS systems.