Compact Kerr comb based on fiber Fabry–Pérot microresonator with few-GHz repetition rate

Optical frequency combs with repetition rates in the 1–10 GHz range are critical for precision spectroscopy and low-noise microwave synthesis, because their densely packed comb lines bridge high-resolution frequency calibration with mature radio frequency electronics. Generating low-noise Kerr frequency combs in this regime within a compact package remains challenging. Here, we address this challenge using a few-mode fiber Fabry–Pérot resonator (FM-FFPR) with a quality factor Q up to 4.0 × 109, packaged within a compact footprint of 85 × 90 × 25 mm3. Self-injection locking of a distributed feedback laser diode to the FM-FFPR narrows the pump linewidth and enables stable soliton generation at a repetition rate of 1.7 GHz. The repetition rate phase noise closely approaches the quantum noise limit, reaching −105 dBc/Hz at 100 Hz offset, with an intrinsic integrated timing jitter of 6.7 fs (100 Hz–10 MHz) and an Allan deviation below 3 × 10−11 at 1 s averaging time. These results establish the FM-FFPR microcomb as a viable platform for compact, low-noise optical frequency comb systems at few-GHz repetition rates, with potential applications spanning photonic microwave generation, dual-comb measurement, and precision sensing.