Dual-Wavelength Fiber Laser Inscribed by Femtosecond Laser in High-Erbium-Doped Fiber

A femtosecond (fs) laser direct inscribing dual-wavelength fiber laser was proposed and experimentally demonstrated. A unique double-peak reflection spectrum can be produced when a fiber Bragg grating (FBG) is inscribed by fs laser point-by-point inscription in a high-erbium-doped fiber (HEDF). By inscribing two such FBGs in the core of an HEDF with a separation of 2 cm, a two-mode laser output can be obtained with dual wavelengths of 1544.428 nm and 1549.812 nm. The laser has a slope efficiency of 1.14% and a maximum output power of 4.6 mW. This simple-structure dual-wavelength fiber laser is expected to be used in multi-wavelength laser sensors and communication devices to reduce cost and improve performance.