Cr2+:ZnSe laser in the infrared region

The mid-infrared (mid-IR) radiation is of great interest for a wide range of scientific and technological applications of spectroscopy and frequency metrology of information technology, industrial process control, photochemistry, photobiology and photomedicine. The "mid infrared'' region covers the portion of the electromagnetic spectrum between 2 to 5 µm at room temperature. Covers important atmospheric windows, and numerous molecular gases, toxic agents, air, water, and soil pollutants, components of human breath, and several explosive agents have strong absorption fingerprints in this region. There are many sources give mid infrared laser, this research focus on one source called Cr2+: ZnSe solid state laser in the mid infrared region. This source is known as "molecular fingerprint". In recent years Cr2+: ZnSe also emerged as mid infrared region laser in a solid material. The Cr2+: ZnSe depends on the ion-host combination material. On the other hand, more than 40 years after the invention of the laser, much of the mid-IR spectrum still remains inaccessible to conventional lasers due to fundamental limitations, most notably a lack of suitable crystalline laser gain materials. This has confined the spectral range of conventional solid-state lasers, mainly to wavelengths below ∼3 μm, resulting in a severe shortage of coherent laser sources at longer wavelengths, and presenting a major obstacle to the widespread advancement of mid-IR science and technology. At the same time, alternative technologies for the generation of mid-IR radiation has been proposed, devised and developed, with the goal of overcoming this persistent barrier. In particular, over the past decade, there have been major new developments in mid-IR sources, driven by the emergence of a number of new technologies and continuing innovations and refinements in many of the more established techniques. The Cr2+: ZnSe pump by thulium fiber laser at 1.800 µm. The first process, sample must be grown and doped with Cr2+ ion. Diffusion is the best factor appears during the sample preparation, diffusion depends on the same factors such as temperature and concentration. The diffusion can be defined as spread out of particle (an atom, ion or molecule…) through random motion from higher concentration region to lower concentration region. The concentration and diffusion have a great role in Cr2+: ZnSe. The absorption coefficient is associated strongly with concentration, while the concentration increases the peak absorption increase, The temperature is another factor which is affected on this laser process, the temperature is related to the concentration and diffusion. The emission intensity increase with increasing pump energy density