Chip-based Brillouin processing for carrier recovery in coherent optical communications

TL;DR

This paper introduces a chip-based Brillouin scattering technique for carrier recovery in coherent optical communications, achieving high spectral efficiency and stability without complex digital processing.

Contribution

It presents a novel on-chip SBS approach for carrier recovery that eliminates the need for a separate local oscillator and reduces digital signal processing complexity.

Findings

Achieves up to 116.82 Gbit/sec data rate with SBS-based carrier recovery.

Provides phase and polarization stability on a photonic chip.

Records a small guardband of ~265 MHz, enhancing spectral efficiency.

Abstract

Modern fiber-optic coherent communications employ advanced spectrally-efficient modulation formats that require sophisticated narrow linewidth local oscillators (LOs) and complex digital signal processing (DSP). Here, we establish a novel approach to carrier recovery harnessing large-gain stimulated Brillouin scattering (SBS) on a photonic chip for up to 116.82 Gbit/sec self-coherent optical signals, eliminating the need for a separate LO. In contrast to SBS processing on-fiber, our solution provides phase and polarization stability while the narrow SBS linewidth allows for a record-breaking small guardband of ~265 MHz, resulting in higher spectral-efficiency than benchmark self-coherent schemes. This approach reveals comparable performance to state-of-the-art coherent optical receivers without requiring advanced DSP. Our demonstration develops a low-noise and frequency-preserving filter that synchronously regenerates a low-power narrowband optical tone that could relax the requirements on very-high-order modulation signaling and be useful in long-baseline interferometry for precision optical timing or reconstructing a reference tone for quantum-state measurements.