60 nm tunable multi-wavelength fiber laser with Brillouin gain loop

Abstract

We demonstrate a multi-wavelength fiber laser with Brillouin cavity loop. Brillouin-Erbium fiber laser (BEFL) integrates Brillouin and Erbium gains in the resonate cavity to produce high power multi-wavelength fiber laser. The Brillouin gain loop connects with main ring cavity by port2 of the circulator1. A coil of SMF with a length of 10 km is employed by 3-dB fiber coupler as Brillouin gain medium, and pumped by Brillouin pump (BP), a tunable laser with a maximum output power of 15 dBm to generate Stokes light. The measured results were extracted from the laser system by using 90/10 coupler where 10% power is used for monitoring and measurement purpose while the 90% power is feedback into the laser cavity. A 1550 nm tunable laser diode (LD) provided the BP that can be tuned from 1470 nm to 1580 nm (110 nm tuning range). Two fiber circulators are used as the fiber reflection loops at both ends of the linear cavity. The effect of the erbium-doped fiber amplifier (EDFA) locating at different locations in the cavity BEFL on Stokes wave is experimentally studied. In the experiment, with EDFA in position A, the tunable range and the output power of the multi-wavelength laser were limited by gain saturation of the signals and the self-lasing cavity modes. The self-lasing cavity modes were suppressed without EDFA, but the tunable wavelength range was narrower because of the low gain. By using EDFA at the total reflective side of the linear cavity, more Stokes waves and wider tunable range was observed because the more powerful Stokes feedback light was amplified twice by the EDFA. The peak power of -1.8dBm and the tuning range of 60 nm were obtained. It has many important applications, such as dense wavelength division multiplexing (DWDM) systems, distributed fiber sensing, slow light, and microwave photonics, etc.