Power-Efficient Kerr Frequency Comb Based Tunable Optical Source

We designed and demonstrated a power-efficient highly integrated photonic system, requiring a total power consumption of 1.7 W and producing a spectrally pure coherent optical signal with a wavelength range of 23 nm in the C-band. The system consists of a compact, low-power InP-based photonic integrated coherent receiver, microresonator-based Kerr frequency comb, and agile electronic circuits. The photonic coherent receiver contains a 60-nm widely tunable Y-branch local oscillator (LO) diode laser, a coupler, and a pair of photodetectors. It consumes record-low (approximately 184 mW) electrical power. The optical frequency comb reference has excellent spectral purity, <4 kHz optical linewidth, and good frequency stability. The spectrally pure tunable optical source was produced by offset locking the on-chip LO laser of the integrated receiver to this frequency comb source. A possibility of further stabilization of the frequency comb repetition rate by locking to an external radio frequency synthesizer was demonstrated.