Low-threshold Brillouin laser at 2 µm based on suspended-core chalcogenide fiber.

We present, to the best of our knowledge, the first demonstration of a 2 µm Brillouin laser based on a thulium-doped fiber pump and a chalcogenide fiber. A short 1.5 m piece of suspended-core chalcogenide As38Se62 fiber is employed as a gain medium, taking advantage of its small effective mode area and high Brillouin gain coefficient. A record-low lasing threshold of 52 mW is achieved, which is about 10 times lower than previously demonstrated in silica fiber cavities.