Enhanced multiwavelength random fiber laser based on hybrid optical amplifier incorporating Sagnac loop mirror interferometer

• A MWRFL is generated using a hybrid optical amplifier combined with a polarizer and HNLF. • The optimal lasing spectrum achieves 52 lasing lines within 9.5 nm wavelength bandwidth and high extinction ratio of 20 dB. • The multiwavelength bandwidth is wider than previous structure of MWRFL based on linear cavity. • Removing the HNLF and polarizer degrades spectral flatness and reduced the number of lasing lines to 32. This work presents an enhanced multiwavelength random fiber laser employing a hybrid optical amplifier in combination with high nonlinearity devices, achieved through the integration of a polarizer with highly nonlinear fiber (HNLF). A Sagnac loop mirror interferometer serves as the comb filtering device, while the hybrid optical amplifier comprises an erbium-doped fiber amplifier (EDFA) and a semiconductor optical amplifier (SOA) as gain media. The SOA’s role in the laser cavity is to mitigate mode competition caused by the homogeneous broadening of the EDFA. The multiwavelength performance is enhanced by introducing nonlinear polarization rotation effect through the interaction of the HNLF, SOA, and polarizer (Condition A). The optimal lasing spectrum features 52 lasing lines within a 3 dB uniformity range and a high extinction ratio (ER) of 20 dB. The multiwavelength bandwidth is 9.5 nm, which is broader compared to previous studies on MWRFLs utilizing a linear cavity configuration. Removing the polarizer (Condition B) reduces the number of lasing lines to 51 and the ER to 19 dB. Furthermore, excluding the HNLF (Condition C) from the linear cavity decreases the spectral flatness and lowers the number of lasing lines to 32. A decrease in EDFA power results in fewer lasing lines, and variations in the angle of polarization controller has changed the ER value. Laser stability was evaluated over 2 hours, showing a peak power fluctuation of approximately 4 dB.