Intermediate infrared 4-micron wave band and 3-micron wave band dual-wavelength all-fiber laser

The invention relates to an optical fiber laser, in particular to an intermediate infrared 4-micron waveband and 3-micron waveband dual-wavelength all-optical fiber laser, which is used for solving the problem that an erbium-doped zirconium fluoride all-optical fiber laser adopting a 980nm semiconductor laser pump and a 1970nm/970nm dual-wavelength cascade pump can only obtain 3-micron waveband single output. A 888nm semiconductor laser pumping heavily doped holmium ion indium fluoride fiber laser can only obtain single output of a 4 [mu] m wave band, and a space optical device makes the 4 [mu] m wave band laser difficult in pumping coupling adjustment, low in pumping coupling efficiency, poor in laser structure stability, large in engineering application difficulty and the like. The mid-infrared 4-micron waveband and 3-micron waveband dual-wavelength all-fiber laser comprises a semiconductor laser pumping source, a gain fiber, a 4-micron waveband fiber bragg grating pair and a 3-micron waveband fiber bragg g