Real-Time Mode Following Based Narrow Linewidth Brillouin Fiber Swept Laser

We propose and demonstrate a novel concept of Brillouin fiber swept laser with narrow linewidth based on mode following effect. Utilizing the synergy of the Brillouin gain spectrum and cavity mode, the real-time mode following effect is achieved. In the experiment, a tunable laser source was employed to realize synchronous tuning of Brillouin gain spectrum for matching the shift of cavity mode induced by an intra-cavity piezoelectric transducer wound with gain fiber. We theoretically analyzed the influence of the driving parameters and wound fiber length on the frequency sweep range. Experimental results show that the obtained maximum continuous frequency sweep range is ∼445.76 MHz while the driving frequency is 12 kHz and the wound fiber length is 12 m, which is consistent with the theoretical analysis. This new type of fiber swept laser has huge potential application value in optical sensing and communication system.