Compact and high-resolution spectrometer via Brillouin integrated circuits

TL;DR

This paper presents a compact, high-resolution, chip-integrated spectrometer leveraging Brillouin scattering in a hybrid photonic-phononic chip, achieving unprecedented spectral resolution in a small footprint for advanced optical analysis.

Contribution

The work introduces a novel hybrid photonic-phononic spectrometer utilizing Brillouin scattering, achieving high resolution and dynamic reconfigurability in a compact device.

Findings

Spectral resolution of 0.56 nm over 110 nm bandwidth.

Achieved high reflectivity up to 50% with microsecond switching.

Device size is only 1 mm long, approaching fundamental resolution limits.

Abstract

Optical spectrometers are indispensable tools across various fields, from chemical and biological sensing to astronomical observations and quantum technologies. However, the integration of spectrometers onto photonic chips has been hindered by the low spectral resolution or large device footprint with complex multiple channel operations. Here, we introduce a novel chip-integrated spectrometer by leveraging the acoustically-stimulated Brillouin scattering in a hybrid photonic-phononic chip. The Brillouin interaction provides a dynamic reflection grating with a high reflectivity up to 50% and a fast switching time on the microsecond scale, achieving an unprecedented spectral resolution of 0.56 nm over a 110 nm bandwidth using just a single 1 mm-long straight waveguide. This remarkable performance approaches the fundamental limit of resolution for a given device size, validating the potential of the hybrid photonic-phononic device for efficient and dynamically-reconfigurable spectral analysis, and thus opens up new avenues for advanced optical signal processing and sensing applications.