Thermo-optical and lasing characteristics of Cr^2+-doped CdSe single crystal as tunable coherent source in the mid-infrared

Abstract

We report on a comprehensive characterization of Cr 2+-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 Tmfiber 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.

Generation of nanosecond 2.65 μm pulses and pulse narrowing in fiber-bulk Ho3+:YAG laser pumped gain-switched Cr2+:CdSe laser

“…The simulation results of the spike pulse duration are illustrated by the solid line, which have the same tendencies as the experimental results. Nevertheless, the calculated values were lower than Value [15,26,34] Refractive index at 2.65 μm, n 2.46…”

“…Then interest was inspired in the research of this class of materials, and laser oscillations of Cr 2þdoped ZnSe, ZnS, CdSe, CdMnTe, etc., were gradually realized [11][12][13] . Among the materials, Cr 2þ ∶CdSe attracted plenty of attention for its large emission cross section and ultra-broad emission band (2.2-3.6 μm) [14,15] .…”

“…The values of the parameters come from Refs. [15,26,34]. The pump duration and pump power were the same as that in the experiment.…”

Review of Surface Modification Technologies for Mid‐Infrared Antireflection Microstructures Fabrication

“…Mid‐IR systems are usually implemented as fibers, [ 4,5 ] as waveguides, [ 6,7 ] or as free‐space optics. [ 8,9 ] For these cases, most of the commonly used mid‐IR transparent materials have a high refractive index: often above 2, and in some cases, up to 4 (see Figure ). High Fresnel loss (also known as surface reflection loss) are associated with a high refractive index, such that the transmittance of normal incident light for materials with a refractive index of 1.6 (sapphire optics) decreases by 95% and to 64% for materials with a refractive index of 4 (germanium optics).…”

Structural quality in single crystalline CdSe ingots grown by PVT

“…Cadmium Selenide (Space Group: P63mc (186), a=4.30Å, c=7.01Å)) is mainly employed for nuclear radiation detectors operating at room temperature [1], nonlinear optical devices [2] and as substrate for epitaxial growth [3]. Characterization of Cr2+-doped CdSe single crystal showed that it is an efficient active material for tunable laser applications in the mid-infrared spectral region [4] and that Fe2+ : CdSe can be considered a promising medium for amplification of femtosecond pulses in the middle infrared range up to 6 µm [5]. Thermal, mechanical and chemical stability are important properties of this semiconductor which additionally might not suffer from polarization under applied electric fields [6,7].…”