Brillouin erbium fiber laser generation in a figure-of-eight configuration with double brillouin frequency spacing

This paper presents an experimental finding of a tunable multiwavelength Brillouin-erbium fiber laser with a double-Brillouin-frequency spacing in a figure-of-eight cofiguration. This double-frequency shifter is formed by incorporating a four-port circulator to isolate and circulate the odd-Stokes signals through a gain medium of a 10 km long nonzero dispersion shifted fiber (NZ-DSF). The ebium gain block amplifies the output even-order Stokes signals formed in a ring cavity. Tip to 15 lasing lines with a wavelength spacing of 0.173 nm have been realized at a 980 nm pump power of 50 mW with a Brillouin pump of 3 dBm. The multiwavelength laser source demonstrates a 10 nm tuning range from 1552 to 1562 nm with the optical signal-to-noise ratio of the desired output channels at around 34.5 dB.