Multi-wavelength fiber laser incorporating enhanced four-wave mixing and Brillouin random lasing resonance

A multi-wavelength fiber laser simultaneously incorporating enhanced four-wave mixing and Brillouin random lasing resonance is proposed to generate broadband Brillouin frequency combs. A continuous wave emitted by a tunable laser is firstly sent to an erbium doped fiber amplifier for power amplification to serve as a Brillouin pump (BP) light, accompanied by the repressed wideband gain spectrum of the optical amplifier, is injected into a fiber dual ring cavity. On the one hand, it makes up for the power distribution contradiction between the BP light and the feedback light. On the other hand, the injection of broadband noise induces red shift of the gain spectrum of the optical amplifier within the fiber cavity, significantly enhancing its gain bandwidth. Therefore, stronger power of BP light and feedback light lead to enhanced stimulated Brillouin scattering and Rayleigh scattering in the highly nonlinear fiber, which are fed back to a dispersion shifted fiber, resulting in an enhanced four-wave mixing, the generated Brillouin comb spectrum was greatly extended. In addition, Brillouin random lasing resonance, in combination with broadened erbium gain bandwidth, further intensifies these nonlinear effects. As a result, a record wideband Brillouin comb spanning 100 nm was produced, and it produced 393 comb lines within a peak power variation of 30 dB. The maximum peak variation is only 0.307 dB within a 90-mins test cycle, indicating excellent stability of the proposed system. Finally, a detailed verification of the randomness of Brillouin random lasers was conducted based on the spin glass theory.