[en] Characteristics of a Fe:ZnSe laser are studied at room temperature. The laser active elements are heavily doped single crystals with the ${\text{Fe}}^{2+}$ ion concentration $n=0.64\times <!--\; ??\; -->{10}^{19}-<!--\; ???\; -->5.7\times <!--\; ??\; -->{10}^{19}{\text{cm}}^{-<!--\; ???\; -->3}$, grown from melt by the Bridgman method. The generated energy of 870 mJ is obtained at the total efficiencies with respect to the absorbed and incident energies ${\mathrm{\eta <!--\; ??\; -->}}_{\mathrm{a}\mathrm{b}\mathrm{s}}=43\mathrm{\%<!--\; \%\; -->}$ and ${\mathrm{\eta <!--\; ??\; -->}}_{\mathrm{i}\mathrm{n}\mathrm{c}}\approx <!--\; ???\; -->35\mathrm{\%<!--\; \%\; -->}$, respectively. The laser slope efficiency with respect to the absorbed energy is ${\mathrm{\eta <!--\; ??\; -->}}_{\mathrm{s}\mathrm{l}\mathrm{o}\mathrm{p}\mathrm{e}}\approx <!--\; ???\; -->50\mathrm{\%<!--\; \%\; -->}$. In a heavily doped active element with the ${\text{Fe}}^{2+}$ concentration $n=5.7\times <!--\; ??\; -->{10}^{19}{\text{cm}}^{-<!--\; ???\; -->3}$, in which the medium excitation depth is just a part of the total element dimension along the optical axis (the element is completely non-transparent for the pumping radiation), the radiation spectrum of the Fe:ZnSe laser shifts to the long-wavelength range by more than 300 nm as compared to spectra of the laser on crystals excited along the whole element length. It is shown that Fe:ZnSe lasers on heavily doped single-crystal elements can be efficiently excited by a radiation of a Cr:ZnSe laser without tuning the spectrum of the latter to the longer wavelength range.