|Title||Hybrid InP and SiN integration of an octave-spanning frequency comb|
|Publication Type||Journal Article|
|Year of Publication||2021|
|Authors||T. C. Briles, S-P. Yu, L. Chang, C. Xiang, J. Guo, D. Kinghorn, G. Moille, K. Srinivasan, J. E. Bowers, and S. B. Papp|
Implementing optical-frequency combs with integrated photonics will enable wider use of precision timing signals. Here, we explore the generation of an octave-span, Kerr-microresonator frequency comb using hybrid integration of an InP distributed-feedback laser and a SiN photonic-integrated circuit. We demonstrate electrically pumped and fiber-packaged prototype systems, enabled by self-injection locking. This direct integration of a laser and a microresonator circuit without previously used intervening elements, such as optical modulators and isolators, necessitates understanding self-injection-locking dynamics with octave-span Kerr solitons. In particular, system architectures must adjust to the strong coupling of microresonator backscattering and laser-microresonator frequency detuning that we uncover here. Our work illustrates critical considerations toward realizing a self-referenced frequency comb with integrated photonics.