Dynamic Interplay Between Kerr Combs and Brillouin Lasing in Fiber Cavities

Abstract

Highly coherent frequency combs are of crucial importance for optical synthesis and metrology, spectroscopy, laser ranging, and optical communications. Kerr combs, generated via cascaded nonlinear frequency conversion in a passive optical cavity, typically offer high repetition rates, which is essential for some of these applications. Recently, new ways of generating Kerr combs combining Kerr and Brillouin effects have emerged with the aim of improving some performances, especially in the fiber cavity platform. Direct coherent pumping is replaced by lasing on specific cavity modes, offering easily adjustable repetition rates, and enhanced coherence by Brillouin purification. In this study, such a scheme is implemented and investigated in a non‐reciprocal cavity. Highly coherent combs are demonstrated by finely controlling bi‐chromatic Brillouin lasing and the Kerr comb parameters. A suitable numerical model is introduced to account for the interplay between Brillouin scattering, Kerr effect, and cavity resonant feedback. Quantitative agreements with experiments reveal the importance of the pump lasers detuning in setting the comb's properties, through the mode pulling effect. This phenomenon, along with multi‐mode lasing that impedes the coherence, is not studied in previous fiber‐based demonstrations. These limitations are discussed, and several scaling laws are devised.

Unexpected phase-locked Brillouin Kerr Frequency comb in fiber Fabry Perot resonators

“…However, normal GVD resonators are increasingly utilized for OFCs generation, in particular because of their high conversion efficiency between the pump and the generated comb lines [8,[17][18][19][20]. As the upper branch of a normally dispersive cavity does not exhibit modulation instability, various excitation techniques had to be identified to trigger OFCs in this regime, notably through mode-crossing effect [17,18], Brillouin effect [21], dual-pumping [22], coupled-cavity [18,19,23], modulated pump [20] or pulsed pumping scheme [24][25][26][27][28]. All these tecnhiques rely on the generation of switching waves (SWs) [24,26,[29][30][31], connecting the high and * thomas.bunel@univ-lille.fr low stable states of bistable Kerr cavities.…”