Abstract

The existence of mid-infrared atmospheric transparency window from 4 up to 5 μm provides constant demands for compact and reliable laser sources generating radiation in this wavelength region. Other interest for those radiation can be in medical applications where the 4 - 5 μm radiation could be used for new treatment methods. Laser active materials fulfilling these requirements can be Fe:ZnSe or trivalent dysprosium active ion in a lead thiogallate (PbGa₂S₄ - PGS) matrix [1,2]. The energy transition ⁶H_11/2 → ⁶H_13/2 corresponding to the generated radiation wavelength of ~ 4.3 μm can be excited either at the wavelength of ~ 1.32 μm (pumping to ⁶H_{9/2 +} ⁶F_11/2 energy level), or directly to the ⁶H_11/2 energy level by the ~ 1.7 μm radiation. In our previous experiments, the Dy:PGS laser was pumped by flashlamp pumped Nd:YAG (1.32 μm), Er:YAP (1.66 μm) [3], or Er:YLF (1.73 μm) [4] laser radiation. In case of 1.32 μm excitation, also the low pumping rate source based on diode pumped Nd:YAG laser was used [5]. With the improved setup the energy up to 18 mW in 4 ms long pulses was obtained in the pulsed regime (rep. rate 20 Hz) at 4.3 μm wavelength with slope efficiency 3 % with respect to absorbed pumping energy. This contribution shows the pulsed and CW operation of 1.7 μm diode pumped Dy:PGS laser generating at 4.3 μm region.

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