Development Of CdMgTe and CdMgSe For Optical Switching Applications

Presently, there is an increase need for materials that exhibit strong nonlinear absorption for various military applications. In addition, materials with the following characteristics are desired: variable band gap, a cut-on wavelength of 0.4 through 1.4 micron, and a linear transmission greater than 98 percent from the visible (0.4 micron) through the NIR/SWIR (0.65 through 3 micron). In Phase I, we investigated Cd1-xMgxTe and Cd1-xMgxSe for their usefulness in optical switching applications. These materials have nonlinear absorption in the wavelength range from visible to NIR, and possibly extending to SWIR. Phase II work will further investigate the growth of IIA/B-VIB ternary materials with a goal of standardizing and optimizing the growth procedures that produce device quality crystals. The major challenges in producing and processing these materials include: the highly reactive and corrosive nature of group II A elements and II A- VI compound melts; the phase diagrams of these II-VI materials are not very well understood, and the purity of commercially available group II A elements is only 99.9% which is not adequate to make semiconductor grade materials. As the end result of this Phase II work, we will be capable of producing material that can be directly used as passive optical switching. BENEFIT: Presently, numerous military and commercial systems utilize the mid-wave infrared (MWIR) spectral region for target detection. Unfortunately, a significant amount of spectral information is oftentimes lost because of weather or other environmental conditions. As a result, many systems are utilizing the visible (VIS) to the short wave infrared (SWIR) spectral regions. This has lead to an increase in the need for materials that can provide filtering across multiple broad wavelength regions and have the ability to filter out unwanted information. The materials proposed in this research can be engineered to meet these requirements. Applications include optical limiting, eye and sensor protection, optical pulse shaping, information processing, and laser mode locking.