High-Power, Continuous-Wave 3.0- to 3.5-Micron Emitting Quantum Cascade Semiconductor Laser Navy STTR FY2012.A Sol No.: Navy STTR FY2012.A Topic No.: N12A-T003 Topic Title: High-Power, Continuous-Wave 3.0- to 3.5-Micron Emitting Quantum Cascade Semiconductor Laser Proposal No.: N12A-003-0057 Firm: Intraband LLC 200 N. Prospect Ave. Madison, Wisconsin 53726-4027 Contact: Luke Mawst Phone: (608) 332-2520 Abstract: The technical objectives of this proposal are: 1) the design of 3.0-3.5 micron-emitting quantum cascade laser (QCL) structures grown on metamorphic-buffer-layer (MBL) substrates; 2) the realization of electroluminescent QCL structures on MBLs with emission in the 3.0-3.5-micron wavelength range. Novel tapered active-region (TA) QCLs will be designed to substantially suppress carrier leakage out of their active regions, in order to achieve electro-optic characteristics of low temperature sensitivity. Novel MBL-based approaches will be used for realizing low layer-strain levels for the structure of 3.0-3.5 micron-emitting intersubband-transition semiconductor sources. The design will be for QCLs able to achieve CW operation to at least 0.5 W at room temperature and with high beam quality. A development plan describing monolithic coherent-beam combining of TA QCLs for scaling the spatially coherent CW power to at least 5-10 W levels will be devised. Benefits: Reliable, high coherent power laser sources at 3.0-3.5 microns will enable a host of commercial applications for which no other suitable laser source currently exists. One of the primary values of this wavelength range is that it covers the vibration bands of many important molecular species. The lasers developed under this program can therefore be used to detect, identify and measure these molecules by absorption spectroscopy at large distances. An environmentally significant application is the remote sensing of methane, which is a major source of radiative forcing with a global warming potential 25 times greater than carbon dioxide and whose fundamental absorption line is at ~3.35 microns. Many other hydrocarbon molecules like naphtha also have vibration bands in this wavelength range, and these laser sources can be used to measure their levels or to remotely detect leaks when stored and transported. In commercial manufacturing environments, these lasers can accurately monitor concentrations of reaction chemicals like HCl (3.47 microns) for process control. Additionally, many popular plastics have absorption bands at ~3.4 microns making the lasers ideal for the marking, welding or cutting these materials. Finally, the achievement of watt-range continuous-wave (CW) powers delivered in high-quality beams will be highly beneficial for infrared countermeasures (IRCM) and LIDAR in both military and civilian applications. Return