Ultra-narrow linewidth single-frequency DFB fiber laser based on the CPM-FBG

Utilizing the modulation of the refractive index of the fiber Bragg grating based on the arc discharge process, a scheme of the single frequency narrow linewidth distributed feedback (DFB) fiber laser based on the corrugation-pitch-modulated fiber Bragg grating (CPM-FBG) is proposed. The mathematical model and simulation study of the CPM-FBG is established, and the interest of phase shifted fiber Bragg grating (PSFBG) is proved. An on-line CPM-FBG production system is achieved, and the erbium-doped CPM-FBG is formed. A single-frequency narrow linewidth distributed feedback (DFB) fiber laser is realized, and the laser threshold power is 25.4 mW with 3 dB linewidth at 805 Hz and side mode rejection ratio greater than 48.8 dB.