Phase Stabilization of a Soliton Microcomb Using Microwave Injection Locking

We demonstrate a microwave injection locking (MIL) technique to stabilize the phase of the repetition frequency of a broadband free-running single soliton comb. MIL is achieved by applying amplitude modulation to the pump laser, that generates the soliton in a high-Q Si<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>N<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> microresonator and by locking the free-running soliton comb to the third-order modulation sidebands. We obtain a single sideband phase-noise suppression of 35 dB at a 1-kHz offset from the carrier and an injection locking bandwidth of 60 kHz.