Tunable Random Fiber Laser Based on Dual-Grating Structure

In order to reduce the pumping threshold and achieve a short-cavity single-mode transmission with narrow-linewidth random fiber laser, we propose tunable laser based on combination of grating highly reflective Bragg (FBG). Theoretical modeling refractive index-modulated was carried out. Random is regarded as linear uniform gratings different periods. Simulation calculations were performed using transfer matrix method determine preparation parameters. Under premise satisfying light localization, point-by-point used write in femtosecond according simulated We constructed linewidth 1.68 kHz 29.2 mW FBG combined an erbium-doped fiber. Due broad scattered wavelength range grating, by changing central high-reflection FBG, output realized, 0.847 nm (1549.110–1549.957 nm). Moreover, laser’s power are stable for long time. Compared other lasers, proposed has advantages lower threshold, shorter cavity length, narrower linewidth, relatively simple structure.