2-μm Brillouin laser based on infrared nonlinear glass fibers

Infrared fiber materials such as chalcogenide, tellurite, and heavily germanium-doped silica glasses are attractive materials for many applications based on nonlinear optical effects such as Kerr, Raman, and Brillouin processes. Here, we experimentally demonstrate a close-to-single-frequency Brillouin fiber laser in the 2-μm wavelength region either based on tellurite (TeO₂) glass or on heavily germanium-doped silica glass. Our results reveal a strong enhancement of the Brillouin gain efficiency at 2 μm of more than 50 times that of standard silica optical fibers. A lasing threshold and narrow linewidth of 98 mW and 48 kHz, respectively, have been demonstrated in the tellurite fiber-based laser. This simple Brillouin laser source configuration confirms the potential applications of such fibers for the development of nonlinear photonic devices in the important 2-μm spectral range.