Abstract
We report on a comprehensive characterization of Cr2+-doped CdSe single crystal as an efficient active material for tunable laser applications in the mid-infrared spectral region. Optical gain, thermo-optical behavior, power efficiency, scalability and wavelength tunability have been thoroughly investigated. Using an antireflection-coated crystal pumped by a Tm-fiber laser at at 1.94 μm, 1-W CW output power and 50% slope efficiency at 2.65 μm emission wavelength have been obtained in a diffraction-limited output beam. An output peak power of 2.5 W has been achieved without significant beam distortion in a quasi-CW regime. Exploiting an intra-cavity diffraction grating in a Littrow configuration, a maximum tuning range of 900 nm from 2.22 to 3.12 μm, limited by the finite bandwidth of resonator components, has been demonstrated with an uncoated crystal.
Highlights
We report on a comprehensive characterization of Cr2+-doped CdSe single crystal as an efficient active material for tunable laser applications in the mid-infrared spectral region
Using an antireflection-coated crystal pumped by a Tmfiber laser at at 1.94 μm, 1-W continuous wave (CW) output power and 50% slope efficiency at 2.65 μm emission wavelength have been obtained in a diffraction-limited output beam
Efficient and broad-emission-bandwidth coherent light sources in the middle-infrared spectral region from 2 to 4 μm are of great interest for various applications in the fields of molecular spectroscopy, frequency metrology, industrial material processing, laser surgery, and optical radar systems for atmospheric remote sensing
Summary
Efficient and broad-emission-bandwidth coherent light sources in the middle-infrared (mid-IR) spectral region from 2 to 4 μm are of great interest for various applications in the fields of molecular spectroscopy, frequency metrology, industrial material processing, laser surgery, and optical radar systems for atmospheric remote sensing. Using an antireflection (AR) coated Cr2+:CdSe crystal we demonstrated a diffraction-limited beam with a maximum CW output power of 1 W at the emission wavelength of 2.65 μm with an incident pump power of 2.1 W. Concerning the calculated stress, FEA simulation yields a maximum intensity of 2 · 106 Nm−2 of the equivalent von-Mises stress [20] over a maximum length of 1.5 mm This analysis reveals that for pump intensities approaching 1 GWm−2, the power scalability of Cr:CdSe crystal is mainly limited by thermal lensing and optical beam distortion, being the thermal fracture issue well below the threshold value
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