A stable optical comb with double-Brillouin-frequency spacing assisted by multiple four-wave mixing processes

A stable optical comb with a double-Brillouin-frequency spacing, employing a 2.5-km common single mode fiber (SMF) is proposed and demonstrated experimentally. The simultaneous existence of the first-order and third-order Stokes within the ring cavity excites the higher-order Stokes and anti-Stokes via multiple four-wave mixing (FWM) processes. Ten odd-order Stokes, nine odd-order anti-Stokes and a second-order Stokes signal with a wavelength spacing of 0.172 nm (∼20 GHz) are simultaneously achieved at a Brillouin pump (BP) level of 160 mW. The maximum power fluctuation of the proposed optical comb is less than 1 dB at room temperature within 100 min. The optical comb can show a good stability and flexibility in the choice of operating wavelength.

► A stable optical comb with a double-Brillouin-frequency spacing with 19 channels.
► Exploiting multiple four-wave mixing processes.
► A simple ring cavity structure.
► The optical comb can operate at any wavelength.