Over 5-W Passively Q-Switched Mid-Infrared Fiber Laser With a Wide Continuous Wavelength Tuning Range

We report efficient high-average-power, high-energy passively Q-switched operation of an Er3+-doped fluoride fiber laser at room temperature with wavelength-tunable resonator configuration utilizing a plane ruled grating for wavelength selection. The fiber laser produced stable Q-switched pulses with a maximum average output power of 5.16 W at 2811.7 nm and a maximum pulse energy of 27.7 μJ at 2834.6 nm for 30.5-W launched pump power and could be tuned over a wavelength range of 90 nm from 2762.5 to 2852.5 nm, with > 4-W average power over the range of 76.1 nm. Our results present fivefold increase in output power over previously published values directly attained from ~3-μm passively Q-switched fiber lasers and firmly establish a fiber laser as a compact, wavelength-tunable, multiwatt, tens of microjoules mid-infrared pulse source with large scope of both industrial and scientific applications.