Fig. 1. Experimental setup of narrow linewidth laser

Fig. 2. Schematic diagram of super stable cavity mechanical mechanism

Fig. 3. Cavity transmission signal and error signal of scanning state (left) and locked state (right)
(a): Scan trigger signal; (b): Error signal in scanning state; (c): Cavity transmitted signal in scanning state; (d): Trigger signal in scan off; (e): Error signal in locked state; (f): Cavity transmitted signal in locked state

Fig. 4. Spectrum signal after frequency locking (left) and current feedback PID frequency response (right)
(a): Spectrum signal of cavity reflected light after frequency locking; (b) PID gain characteristic curve; (c): PID phase characteristic curve

Fig. 5. Error signal acquisition in scanning and locking state
(a): Represents the error signal in the scanning state; (b): 20 s error signal after locking

Fig. 6. Frequency distribution statistics of error signals after locking

Fig. 7. Frequency drift for 12 consecutive hours after frequency lock