En route to broadly tunable middle-infrared optically and electrically pumpable Cr2+ and Fe2+ doped II-VI semiconductor lasers

University Of Alabama At Birmingham, Birmingham AL

Investigators

Abstract

The objective of this program is to further explore capabilities of Cr2+:ZnSe crystals as potential candidates for broadly tunable middle infrared lasing under electrical excitation. The hypothesis to be verified in the proposed project is that low dimensional Cr2+:ZnSe structures can provide quantum confinement of the electron-hole pairs in quantum wells and quantum dots accompanied by effective energy transfer from excitons to dopant ions which will enable an efficient pathway for Cr2+ lasing under interband optical or electrical excitation. Our rationale relates to the well known observation that in bulk and thin film ZnSe chromium reduce considerably the efficiency of ZnSe visible emission due to effective free-carrier capture accompanied by intra-center mid-IR emission from Cr2+. Among the problems to be addressed are a) fabrication and characterization of high optical quality and high quantum efficiency Cr doped bulk, thin films, quantum wells and quantum dots prepared by thermal diffusion, pulsed laser deposition, and sol-gel technology, respectively; b) physical mechanisms of the energy pathways between the host and Cr2+ ions under interband and electrical excitation in the bulk and nanostructures c) theoretical modeling and experimental realization of stimulated emission under interband optical excitation as well as electroluminescence in the bulk and the nanostructures. Broader Impacts. The approaches to be investigated will lead to ground-breaking advances for low-cost optically and electrically pumpable broadly tunable mid-IR laser sources which will impact medical, environmental, scientific, and counter-terrorism applications such as: detection of explosives, chemical and biological warfare agents and their precursors, industrial process control, and measurement of medically important molecular compounds in the exhaled breath of patients. The outcome of this development project will be offered as "technology opportunity" for U.S. laser and photonics companies in order to maximize the societal impact of the project. A critical component of the proposed program is training of scientists and engineers. This workforce development will involve (i) incorporation of findings into four courses taught to two campuses of the University of Alabama System, (ii) graduate student training, and (iii) undergraduate student research through REU site. The program will expose graduate and undergraduate students (including those in NSF-funded Alabama Alliance for Minority Participation AMP) at different education levels to topics in lasers, optical spectroscopy, materials and nanophysics. This will encourage the pursuit of graduate and post-graduate work in these fields helping to diversify both science and engineering graduate programs, and the workplace.