Dy:PbGa2S4 laser radiation and its delivery by hollow waveguide

The mid-infrared radiation generated by bulk Dy:PbGa2S4 laser working at room temperature was characterized and for its delivery the special type of COP/Ag hollow waveguide was used. The optical pumping of Dy:PbGa2S4 laser was performed by flashlamp pumped Er:YLF laser at 1.73 μm wavelength. The compact 60 mm long Dy:PbGa2S4 laser oscillator worked in free-running mode with the repetition rate 1.5 Hz. The output energy was 5.1 mJ in 80 μs long pulse at 4.3 μm wavelength. The spatial beam structure was close to the Gaussian shape. The goal of the presented study was the preliminary investigation of the mid-infrared Dy:PbGa2S4 radiation delivery possibility by the cyclic olefin polymer and silver coated hollow glass waveguide. The length of the waveguide was 103 cm and the inner diameter was 700 μm. The thickness of the polymer inner layer was calculated for the optimal 4 μm radiation transmission. Mid-infrared laser radiation was coupled into the waveguide by the CaF2 lens with the focal length 55 mm. The characterization of delivered 4.3 μm radiation was provided. It was observed that the spatial structure is changing essentially, which follows from the transmission principle of the hollow waveguide. As conclude the delivery system for 4.3 μm mid-infrared Dy:PbGa2S4 laser radiation was investigated for the first time.