We demonstrate two gain-switched 2400 nm Cr:ZnSe lasers with 4.7 and 0.72 ns pulse durations pumped by 1645 nm Er:YAG and 1907 nm Raman-shifted Nd:YAG radiations, respectively, achieving pulse compression factors of 24 and 15.

Chromium-doped zinc selenide (Cr:ZnSe) crystals are the gain media of choice for mid-infrared lasers operating over a 1.9–3.4 µm spectral range. In this study, we used laser-induced breakdown spectroscopy (LIBS) of Cr:ZnSe polycrystalline materials to improve the sensitivity of detecting chromium concentration in the laser-active materials. The fundamental harmonic of a Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser was used as an excitation source. After calibration of the LIBS signal, we calculated that chromium's limit of detection (LOD) was 30 parts per million (ppm). Normalization of the Cr(I) intensity peak at 357.9 nm by the square root of the Zn(I) peak at 636.2 nm reduced the LOD to 20 ppm and increased the coefficient of determination to R² ≈ 0.98. These results demonstrate the potential of LIBS for microscale mapping of dopant distributions in laser crystals and for on-site monitoring of material quality during fabrication.

Lasers operating in the middle infrared (mid-IR) region are useful for various applications ranging from free-space communication to biological tissue characterization. Transition metal-doped, particularly Cr and Fe, II-VI compounds, are key materials for mid-IR lasers operating in the 2-5 mu m range. However, producing high-quality transition metal-doped ZnSe crystals is challenging due to limitations in conventional doping methods. This study investigates the fabrication of transparent ZnSe ceramics using spark-plasma sintering (SPS). Sintering was conducted at pressures up to 90 MPa and temperatures up to 1100 degrees C under a vacuum with argon gas purging. The resulting ceramics achieved 99.9% density relative to single crystals. Transparent ZnSe and Fe:ZnSe ceramics, with transparencies of up to 52% and 33%, respectively, at 15 mu m, were fabricated. The successful fabrication of these transparent ZnSe and Fe:ZnSe ceramics demonstrates the viability of SPS as a method for producing TM-doped ceramic mid-IR gain media.

We present the modeling and experimental characterization of a room-temperature, sub-nanosecond, gain-switched (GS) Fe:ZnSe laser operating at 4.4–4.8 μm. As pump sources, we used a 2.79 µm Q-switched Cr:Er:YSGG laser with a pulse duration of 52 ns and the 2.98 μm idler of a Nd:YAG pumped KTA-OPO system with a pulse duration of 9 ns. The shortest pulse durations were measured to be 1.4 ns and 0.7 ns under excitation by the Cr:Er:YSGG laser and KTA-OPO system, respectively. The developed Fe:ZnSe laser model showed good agreement with the experimental results. Optimization of the laser parameters based on model simulations suggests that an Fe:ZnSe microchip laser configuration could be achieved with a pulse duration of ~250 ps and an efficiency of ~20%.

Ultrashort light sources in the middle-infrared range are highly beneficial for applications such as gas molecular spectroscopy, remote sensing, atmospheric science, medical treatments, and light-matter interaction studies. Ultrafast lasers utilizing chromium-doped ZnS/Se (Cr:ZnS/Se) have proven to be robust and stable solutions within this spectral region. Nonlinear spectral broadening is fundamentally important, as it pushes the pulse duration limits imposed by the bandwidth of laser media. In this study, we demonstrate the spectral broadening and supercontinuum generation in several bulk materials, including InP, Si, GaN, GaAs, PbMoO4, YVO4, diamond, and TiO2, using pump radiation with up to 4 W average power centered at 2.35 mu m from a Cr:ZnS femtosecond MOPA system. Some of the investigated materials have excellent potential as effective media for middle-infrared supercontinuum generation, demonstrating the feasibility of developing a single-cycle pulse middle-infrared laser system. (c) 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Sub-nanosecond mid-IR lasers are essential for applications like optical parametric amplification and material processing, yet effective sources are limited. This study explores room temperature gain-switched (GS) Fe:ZnSe lasers at 4.4-4.6 mu m, focusing on spike-like oscillation dynamics to generate sub-ns pulses from 9 ns KTA-based OPO pump pulses. We suppressed relaxation oscillations by optimizing cavity length, gain element length, and output coupler reflectivity for single-pulse oscillation regime and obtained single-pulse GS operation. Numerical approximation predicted an output pulse with 850 ps pulse duration. Experimentally, single-spike oscillation yielded output energy as high as 1.05 mJ (Delta t = 841 ps) with 16 mJ pumping from the 2.98 mu m KTA-OPO idler. This corresponds to a peak power of 1.25 MW. These findings demonstrate the potential of Fe lasers for high-energy, ultra-short pulse generation in the mid-infrared range.

We present a Cr:ZnS Kerr-lens mode-locked master oscillator-single-pass amplifier scheme for supercontinuum generation in nonlinear materials. The amplified output radiation was broadened in bulk InP over the 1800-3000 spectral range at a −30 dB level.

We report on room temperature tunable mid-IR Fe:ZnSe laser system pumped by radiation of electro-optically Q-switched Cr:Er:YSGG MOPA system. The output energy of 55mJ at 4400 nm was demonstrated in 90 ns pulses.

High levels of heavy metal contamination in soil present substantial threats to human health and the environment, leading to severe health problems such as neurotoxicity, cancer, kidney issues, chronic obstructive pulmonary disease, and reduced life expectancy. This research aims to identify and analyze heavy metals in soil samples collected from Superfund sites in North Birmingham, Alabama, specifically in affected areas with zip codes 35207 and 35217 and control area 35214. These affected areas were previously used for mining, coal-fired power plants, coke furnaces, smelting, and other potential sources of heavy metal pollution. Laser-induced breakdown spectroscopy (LIBS) was employed to study 60 soil samples systematically collected from affected and control areas. We found that by using LIBS, we could detect arsenic (As), lead (Pb), and manganese (Mn) in all soil samples from the affected areas. The limit of detection (LoD) was 29.5 mg/kg for Pb, 95.5 mg/kg for As, and 327 mg/kg for Mn using specific parameters of the detection system and/or argon gas purging at atmospheric pressure. The results were compared with ICP-MS measurements to validate the accuracy of the LIBS findings. The data showed good linearity for all calibration data at relatively low concentrations and a good correlation with ICP-MS measurements.

We report on the experimental characterization and modeling of sub-nanosecond Fe: ZnSe mid-IR gain-switched laser operating at room temperature. A single-spike oscillation with an output energy of 0.33 mJ was achieved under 4.67 mJ pump energy.

We report on 2.79μm flashlamp-pumped electro optically Q-switched Cr:Er:Ysgg lasers with the La 3 Ga 5 SiO 14 Q-switch. The “short”(“long”) cavity oscillators demonstrated up to 300(190)mJ output energy in 15(85)ns pulses at a 3Hz repetition rate. In the 2.9m long MOPA configuration, 300mJ was reached at l00ns pulse duration.

We report on 2.79μm flashlamp-pumped electro optically Q-switched Cr:Er:Ysgg lasers with the La3Ga5SiO14 Q-switch. The “short”(“long”) cavity oscillators demonstrated up to 300(190)mJ output energy in 15(85)ns pulses at a 3Hz repetition rate. In the 2.9m long MOPA configuration, 300mJ was reached at l00ns pulse duration.

We report on 2.79μm flashlamp-pumped electro optically Q-switched Cr:Er:Ysgg lasers with the La <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</inf> Q-switch. The “short”(“long”) cavity oscillators demonstrated up to 300(190)mJ output energy in 15(85)ns pulses at a 3Hz repetition rate. In the 2.9m long MOPA configuration, 300mJ was reached at l00ns pulse duration.

We report on developing three flashlamp-pumped electro-optically Q-switched Cr:Er:YSGG lasers with the Q-switch based on a La3Ga5SiO14 crystal. The "short" laser cavity was optimized for high peak power applications. In this cavity, 300 mJ output energy in 15 ns pulses at a 3 Hz repetition rate was demonstrated with pump energy below 52 J. However, several applications, such as Fe:ZnSe pumping in a gain-switched regime, require longer (∼ 100 ns) pump pulse duration. We developed a 2.9 m long laser cavity that delivers 190 mJ of output energy in 85 ns pulses for these applications. We also demonstrated the Cr:Er:YSGG MOPA system producing 350 mJ output energy at 90 ns pulse duration and 47.5 J of pumping, corresponding to an amplification factor of 3.

It was demonstrated that in the nonselective cavities, suppression of the spatial hole burning via "mode twisting" for lasers based on polycrystalline Cr:ZnS and Cr:ZnSe results in linewidth narrowing to ~80-90 pm from ~20-50 nm.

We report on a 2.79 μm flashlamp pumped electro-optically Q-switched Cr:Er:YSGG laser. The maximum output energy of 190mJ was demonstrated in 85 ns pulses at a 3 Hz repetition rate.

We report on 2.79μm flashlamp-pumped electro optically Q-switched Cr:Er:Ysgg lasers with the La3Ga5SiO14 Q-switch. The “short”(“long”) cavity oscillators demonstrated up to 300(190)mJ output energy in 15(85)ns pulses at a 3Hz repetition rate. In the 2.9m long MOPA configuration, 300mJ was reached at l00ns pulse duration.