Fig. 1. Experimental setup of MPF

Fig. 2. Side mode suppression principle of dual-channel narrow bandwidth Brillouin fiber laser MPF. (a) Vernier effect principle; (b) MPF response effect diagram based on dual-wavelength single-longitudinal-mode Brillouin fiber laser

Fig. 3. Principle of dual-channel narrow-bandwidth Brillouin fiber laser MPF. (a) Generation of frequency-shifted optical carrier; (b) generation of dual-sideband swept signal light; (c) upper sideband of DSB modulated signal amplified by dual-wavelength Brillouin fiber laser; (d) response of MPF

Fig. 4. Spectrum of pump injected SMF

Fig. 5. Frequency response corresponding to MPF before and after access to sub-ring cavity. (a) Frequency response of single ring cavity at 5.735 GHz and 16.475 GHz respectively; (b) results of suppression of comb tooth edge mode by dual-ring cavity, illustrations are bandwidths of two passbands respectively

Fig. 6. Stability measurements at filter center frequency of 5.735 GHz