Harmonics Generation in Large-Mode-Area Cr:ZnS Waveguide Amplifier

The mid-infrared (mid-IR) wavelength range between 2 and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5\ \upmu \mathrm{m}$</tex>, which is often called a “molecular finger-print” region, is characterized by the presence of strong fundamental and overtone rovibrational absorption bands of atmospheric constituents, vapors, and gases, such as carbon monoxide and dioxide, methane, ammonia, NOx, etc. This makes ultra-broadband Cr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup>- II-VI compound-based lasers particularly attractive for various environmental and climate change-related sensing tasks [1]–[3]. Due to the lattice-matched to Si and because the Cr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup>:ZnS operation wavelength range of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2-3.1\ \upmu \mathrm{m}$</tex> lies well in the transparency window of Si, Cr<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup>-doped ZnS laser may provide a path for direct integration with Si photonics allows for high-power broadest tunable and few-cycle ultra-fast laser operation, including frequency combs even in the directly diode-pumped setups.