Characterization and Repetition Rate Locking of a 1 GHz Erbium‐Doped ZBLAN Waveguide‐Chip Comb Laser

A compact, self‐starting, passively mode‐locked erbium‐doped ZBLAN waveguide chip laser operating at a 1 GHz repetition rate and actively stabilized to an RF reference is reported. The laser generates stable pulse with a duration of 324 fs and a bandwidth of 12 nm at an average output power of 13 mW and relative intensity noise below −140 dBc/Hz (100 Hz). Repetition‐rate locking is implemented via piezoelectric cavity‐length control. The resulting repetition‐rate linewidth is reduced to 2 Hz, and up to 60 dB suppression of phase and frequency noise. Potential applications of this GHz comb include time transfer, spectroscopy, and remote sensing.