Peak-power-efficient GHz fiber frequency comb with long-term stability enabled by silica-integrated architecture

Gigahertz-repetition-rate optical frequency combs offer unique advantages for high-speed spectroscopy, precision metrology, and astronomical instrumentation, yet practical implementations remain challenged by limited peak power, architectural complexity, and long-term instability. Here we demonstrate a fully stabilized 1 μm gigahertz fiber frequency comb in which high peak power is delivered directly from the oscillator, eliminating the need for external amplification and pulse recompression. The oscillator produces 54 fs pulses that enable direct octave-spanning supercontinuum generation in a tapered photonic crystal fiber (PCF). The resulting spectrum spans 467–1470 nm and supports robust f −2 f self-referencing using a compact common-path interferometer. Both the repetition rate and carrier-envelope-offset frequency remain phase-locked over multi-day operation, with in-loop fractional instability reaching the 10 −20 level at 10,000 s averaging time. These results establish a compact, fiber-based gigahertz comb platform that combines octave bandwidth with sustained long-term stability, providing a practical route toward robust high-repetition-rate coherent sources for precision photonic applications.