A tunable narrow-linewidth Raman laser based on high quality packaged microrod resonator

The enhancement of the microcavity quality factor contributes to fundamental linewidth reduction in microcavity lasers. This study demonstrates silica microrod resonators with quality factors approaching 10⁹, fabricated by CO₂ laser reflow technology. To improve practical applicability, low-loss package techniques were developed, yielding packaged resonators with optimized optical performance. Using this platform, stimulated Raman lasing was achieved with a pump mode Q-factor of 1.333 × 10⁹, exhibiting a threshold of 0.765 mW. The laser output stability was characterized by a standard deviation of 0.671 mV over 45 minutes of operation, with corresponding Allan deviation analysis. At the maximum output power of 106.4 μW, the measured frequency noise spectral density reached 0.46 Hz²/Hz, corresponding to a linewidth of 2.89 Hz. Thermal tuning of the packaged module achieved a wavelength shift of 0.206 nm, with a temperature sensitivity of 8.92 pm/°C. This work establishes a new technical pathway for developing compact narrow-linewidth lasers, showing significant potential for medical diagnostics, optical communications, and defense applications.