  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 ofan
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
microresonatorcircuit without previously used intervening elements, like
optical modulators and isolators, necessitates understand-ing
self-injection-locking dynamics with octave-span Kerr solitons. In particular,
system architectures must adjust tothe strong coupling of microresonator
back-scattering and laser-microresonator frequency detuning that we
uncoverhere. Our work illustrates critical considerations towards realizing a
self-referenced frequency comb with integratedphotonics.
