Coexistence of multiple microcombs in monochromatically pumped Si3N4 microresonators

We experimentally demonstrate that multiple microcombs can coexist in monochromatically pumped Si3N4 microresonators. By pumping around the mode crossing using a CW laser with mixed polarization, three types of coherent microcombs are generated simultaneously: (i) TE-polarized soliton microcomb; (ii) TM-polarized Turing rolls microcomb; and (iii) cross-phase-modulation-induced TM-polarized microcomb. It is proved that the type-(iii) microcomb shares the same comb line spacing with the type-(i) microcomb although the free spectral ranges of TE and TM modes are different. In addition, a 22.95-GHz signal is extracted from a similar to 100-GHz microresonator by heterodyning the TE and TM comb lines, and phase noise analysis reveals their coherence characteristics. (C) 2022 Optica Publishing Group

Automated summary

The experimental results demonstrate that multiple coherent microcombs can coexist in monochromatically pumped Si3N4 microresonators, including TE-polarized soliton microcombs, TM-polarized Turing rolls microcombs, and cross-phase-modulation-induced TM-polarized microcombs. By heterodyning the comb lines, a specific frequency signal is extracted from the microresonator, and its coherence characteristics are analyzed.