Temporal soliton generation in an ultra-high-effective-Q Kerr resonator enabled by Raman gain

TL;DR

This paper demonstrates the generation of stable temporal cavity solitons and low-repetition-rate frequency combs in a fiber ring cavity with ultra-high effective finesse enabled by distributed Raman amplification, analyzing the associated noise trade-offs.

Contribution

It introduces a method to reconfigure cavity finesse using Raman gain, enabling stable soliton formation at unprecedented finesse levels.

Findings

Achieved an effective finesse of approximately 800.

Generated a low-repetition-rate frequency comb with 580 kHz spacing.

Identified a trade-off between soliton stability and noise due to Raman gain.

Abstract

We demonstrate temporal pattern formation in a coherently driven fiber ring cavity whose effective finesse is continuously reconfigured using distributed Raman amplification. We achieve an effective finesse of up to $\mathcal{F}_{\mathrm{eff}}\approx800$, corresponding to a linewidth of approximately 725 Hz ($Q\approx2.7\times10^{11}$) at 1555 nm. By exploiting the resulting increase in effective photon lifetime, we excite stable temporal cavity solitons and generate a low-repetition-rate frequency comb with a spacing of 580~kHz. Finally, we analyze the impact of the Raman loss-compensation mechanism, particularly its associated noise and show that a trade-off exists between soliton excitation threshold and stability.