A 2-nm mode-hop-free tunable 1018-nm DBR single-frequency low-noise fiber laser

This paper presents a comprehensive optimization of tuning capability and noise characteristics in 1018-nm distributed Bragg reflector (DBR) single-frequency fiber lasers. By implementing an advanced doped fiber design and a dual-stage precision thermal control system, for the first time, we demonstrate a fusion-spliced DBR fiber laser incorporating an 8-mm Yb-doped fiber that achieves >2 nm mode-hop-free continuous tuning across an extended temperature range of -20 °C to 175 °C. The integration of a piezoelectric transducer (PZT) tuning mechanism enables rapid frequency adjustment with a 10-GHz tuning bandwidth. Regarding noise performance, the combination of ultra-stable temperature regulation and a specially designed low-noise laser diode (LD) pump driver achieves remarkable improvements: the intrinsic linewidth is reduced from 3 kHz (free-running) to 800 Hz, while the intensity noise exhibits suppressed relaxation oscillations below -137 dBc/Hz. These performance advancements establish this laser system as an exceptional optical source for precision microwave measurements based on Rydberg atom spectroscopy.