Phase-locking in Multi-Frequency Brillouin Oscillator via Four Wave Mixing

TL;DR

This paper explores how four-wave mixing stabilizes phase-locking in cascaded Brillouin Stokes waves within a fiber resonator, enabling stable, high-repetition-rate picosecond pulse sources for optical communications.

Contribution

It demonstrates the phase-locking mechanism of pump and Stokes waves via FWM in a fiber resonator, supported by experimental and numerical evidence.

Findings

Phase-locked steady states observed in specific parameter regimes.

Real-time measurements confirm pulse stability over time.

Numerical simulations align with experimental results.

Abstract

Stimulated Brillouin scattering (SBS) and Kerr-nonlinear four wave-mixing (FWM) are among the most important and widely studied nonlinear effects in optical fibres. At high powers SBS can be cascaded producing multiple Stokes waves spaced by the Brillouin frequency shift. Here, we investigate the complex nonlinear interaction of the cascade of Stokes waves, generated in a Fabry-Perot chalcogenide fibre resonator through the combined action of SBS and FWM. We demonstrate the existence of parameter regimes, in which pump and Stokes waves attain a phase-locked steady state. Real-time measurements of 40ps pulses with 8GHz repetition rate are presented, confirming short-and long-term stability. Numerical simulations qualitatively agree with experiments and show the significance of FWM in phase-locking of pump and Stokes waves. Our findings can be applied for the design of novel picosecond pulse sources with GHz repetition rate for optical communication systems.