Pump power optimization for linear cavity multiwavelength Brillouin–Raman fiber laser

The optimization of the pump power of L-band multiwavelength Brillouin–Raman fiber laser utilizing a linear cavity is experimentally demonstrated. We determine the optimum Raman pump power (RPP) in which the maximum number of Brillouin Stokes lines, a wide tuning range, and a high optical signal-to-noise ratio (OSNR) can be obtained. Two different dispersion compensating fiber lengths (1.18 and 7.1 km) are used in this work. The number of Brillouin Stokes lines is saturated in the moderate Raman pump region, and both the tuning range and OSNR decrease with increasing RPP. The tuning range decreases from 20 nm to 13 nm and from 27 nm to 16.5 nm and the OSNR decreases from 18.6 dB to 15.3 dB and from 19.3 dB to 16.6 dB for the 1.18 and 7.1 km fiber lengths, respectively. The optimum RPP is identified at 500 mW for the 1.18 km fiber length and at 325 mW for the 7.1 km fiber length.