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Energy and spectral–temporal characteristics of lasers on heavily doped single crystals Fe:ZnSe are studied. With the cavity formed by faces of the crystal at a bivalent iron concentration of 2.8 × 1019 cm−3, the slope and total laser efficiencies with respect to the absorbed energy were 53% and ≈ 42%, respectively. Laser spectra with the cavity free of air and elements capable of forming Fabry–Perot interferometers were recorded using a monochromator with an HPL-256-500 (HEIMANN Sensor) pyroelectric line photodetector. The spectra have a periodical structure with the period of about ≈ 4 cm−1. A similar periodical structure was observed in other cavity types with active elements differing in thickness, production technology, and even crystal material (Fe:ZnSe, Fe:ZnS). Presently, we have no adequate explanation for such a periodical structure. A simple method is suggested for obtaining nanosecond radiation pulses in the spectral range of 4–5 µm based on heavily doped Fe:ZnSe single crystals. [ABSTRACT FROM AUTHOR]

Characteristics of a Fe:ZnSe laser are studied at room temperature. The laser active elements are heavily doped single crystals with the Fe 2 + ion concentration n = 0.64 × 10 19 - 5.7 × 10 19 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 η abs = 43 % and η inc ≈ 35 % , respectively. The laser slope efficiency with respect to the absorbed energy is η slope ≈ 50 % . In a heavily doped active element with the Fe 2 + concentration n = 5.7 × 10 19 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. [ABSTRACT FROM AUTHOR]