Energy scaling of 4.3 μm room temperature Fe:ZnSe laser.

We demonstrate a fourfold increase of the output energy of the gain-switched mid-IR Fe:ZnSe laser. Iron doping of the ZnSe polycrystalline samples was realized using a postgrowth thermal-diffusion method from the metal film. Gain-switched Er:Cr:YSGG (2.8 μm) laser pumped Fe:ZnSe lasing was studied in a Fabry-Perot cavity over a 236-300 K temperature range. The maximum output energy reached 4.7 mJ at 4.3 μm and 3.6 mJ at 4.37 μm at 236 K and 300 K and was limited only by available pump energy. The laser threshold was about 8 mJ and was practically unchanged over the studied temperature range. The laser slope efficiencies, measured with respect to the input pump energy, decreased from 19% to 16% with an increase of temperature from 236 to 300 K. The output radiation featured a Gaussian spatial profile with M(2) = 2.6.