Chromium-doped chalcogenide lasers

Abstract

Broadly tunable near-and mid-infrared lasers are of interest for a variety of applications including high-resolution spectroscopy, metrology, pumping of nonlinear optical frequency converters such as optical parametric oscillators (OPOs) and standoff chemical sensing. Tunable laser sources in the 2-3 µm region include Cr 2+ -doped chalcogenide lasers; cryogenic systems, such as color center lasers; limited tunability devices, such as Tm and Ho lasers, gas or chemical lasers, and diode lasers; and nonlinear optical devices such as OPOs. Transition-metal-doped chalcogenide lasers are of high interest because of their high versatility, broad room-temperature wavelength tunability, high optical efficiencies, and their potential to be scaled to high powers via direct diode or fiber laser pumping. To date, continuouswave, gain-switched, Q-switched and mode-locked laser operation has been demonstrated. Material advantages include broad absorption and emission bands, high fluorescence quantum efficiencies at room temperature, high gain crosssections, and minimal loss mechanisms such as excited-state absorption or upconversion. Additionally, the materials can be produced by a variety of methods, including several direct growth techniques and diffusion doping. The principal material disadvantages include a relatively large change in refractive index with temperature (large dn/dT), which can induce thermal lensing, and a short, microseconds, energy storage time. In this paper we review fundamental material properties, the current state-of-the-art of continuous-wave and pulsed Cr 2+ doped chalcogenide lasers, and recent research results.

Measurement and modeling of infrared nonlinear absorption coefficients and laser-induced damage thresholds in Ge and GaSb

“…An advantage of breaking the pulse into elements is that a non-Gaussian temporal profile can be implemented, which allows the accurate modeling of nonlinear coefficients even if the input pulse has a unusual time profile, which is typical of gain-switched lasers [21,22]. When appropriate, the FD model either used a Gaussian profile or was modified to accept the measured temporal profile from a gain-switched Cr 2+ : ZnSe nanosecond laser.…”

Energy scaling of nanosecond gain-switched Cr2+:ZnSe lasers

“…Transitions to high-lying excited states are spin forbidden, which gives this laser advantages over earlier TM lasers such as Co 2+ and Ni 2+ [6,7]. Benefits of Cr:ZnSe lasers include compactness, up to 63% conversion efficiency [8], pure CW power up to 14 W [9,10], and pulsed average power up to 18.5 W [11]. However, the maximum gain-switched pulse energy with ns pulse durations has been limited to a few mJ for many years.…”

10-watt room-temperature Er-fiber-laser-pumped pure CW polycrystalline Cr2+:ZnS laser

“…[1][2][3][4][5][6] Much attention has been devoted to the development of Cr 2+ :ZnSe lasers due to their excellent lasing and optical properties in the mid-IR spectral region. The laser action of Cr 2+ :ZnSe in continuous wave (CW) regime of operation with efficiency 7 exceeding 60%, power levels 8 in excess of 1.8 W, gain switched pulsed lasing 9 with average output power of up to 18.5 W, and CW wavelength tunability 10 spanning 1880-3100 nm have been reported. Recent progress 11 in fabrication of high-quality Cr 2+ :ZnSe laser crystals has resulted in demonstration of multi-Watt output powers of pure CW, Er/Tm-fiber laser pumped Cr 2+ :ZnSe laser systems.…”