Cr:ZnMgSe laser pumped by 1.7 μm Er:YLF radiation

The aim of the presented work is to demonstrate operation of a Cr:ZnMgSe laser pumped by a Er:YLF laser. Laser output characteristics are compared with a Cr:ZnSe laser operated under similar conditions. Pumping 1.73 mu m Er:YLF laser (Er:YLF rod 80 mm long, flashlamp-pumped) radiation was focused into the Cr:ZnMgSe or Cr:ZnSe active crystal (thickness 4.9 mm and 2.2 mm, respectively; absorption coeficient 4.5 and 10.9 cm(-1) @ 1.73 mu m, respectively). The active crystal was inserted into the stable non-selective optical resonator or into the resonator with a wavelength-selective element. The 65 mm long non-selective resonator was formed by a flat dichroic pumping mirror (HT @ 1.74 mu m, HR @ 2.4 mu m), and a concave output coupler (R = 82 % @ 2.4 mu m, r = 500 mm). The maximal output pulse energy and efficiency with respect to the absorbed pumping energy were measured 5.8 mJ and 36 % for the Cr:ZnMgSe laser, and 10.2 mJ and 76 % for the Cr:ZnSe laser. Central emission wavelength was 2.46 mu m and 2.4 mu m for the Cr:ZnMgSe and Cr:ZnSe laser, respectively. The spectral line-width was about 55 nm in both cases. In the case of 80 mm long output wavelength selective resonator the MgF2 Lyot filter was inserted between the active crystal and the output coupler. Output wavelength tuning was obtained in the range 2.35 - 2.55 mu m and 2.29 - 2.53 mu m for the Cr:ZnMgSe and Cr:ZnSe laser, respectively. Maximum output energy was similar to 4 mJ in both cases.