Highly localized Brillouin scattering response in a photonic integrated circuit

TL;DR

This paper demonstrates a high-resolution, localized measurement technique for Brillouin scattering in photonic integrated circuits, enabling detailed analysis of opto-acoustic properties crucial for advancing SBS-based on-chip devices.

Contribution

It introduces a Brillouin optical correlation domain analysis method for spatially resolved SBS spectrum measurement on-chip, providing new insights into local waveguide properties.

Findings

Achieved 800 μm spatial resolution in SBS measurement.

Mapped local Brillouin frequency shift and linewidth along a spiral waveguide.

Provided detailed opto-acoustic property profiles for photonic-phononic waveguides.

Abstract

The interaction of optical and acoustic waves via stimulated Brillouin scattering (SBS) has recently reached on-chip platforms, which has opened new fields of applications ranging from integrated microwave photonics and on-chip narrow-linewidth lasers, to phonon-based optical delay and signal processing schemes. Since SBS is an effect that scales exponentially with interaction length, on-chip implementation on a short length scale is challenging, requiring carefully designed waveguides with optimized opto-acoustic overlap. In this work, we use the principle of Brillouin optical correlation domain analysis (BOCDA) to locally measure the SBS spectrum with high spatial resolution of 800 {\mu}m and perform a distributed measurement of the Brillouin spectrum along a spiral waveguide in a photonic integrated circuit (PIC). This approach gives access to local opto-acoustic properties of the waveguides, including the Brillouin frequency shift (BFS) and linewidth, essential information for the further development of high quality photonic-phononic waveguides for SBS applications.