High Power Mid-Infrared Quantum Cascade Lasers

RJM Semiconductor with subcontract support from University of Connecticut proposes to develop tunable high power mid-infrared Quantum Cascade Lasers (QCLs) over the 2-10mm wavelength range. These QCL sources have important applications in spectroscopicsensing of chemical weapons and explosives and also can be used in secure free-space optical communications links and infrared countermeasures. We plan to utilize an innovative active region design which uses double-phonon resonance for better hightemperature continuous wave (CW) performance and an integrated thermoelectric controller and multi-section architecture in order to fabricate lasers with continuous tunability. This combined with a new distributed feedback laser design would enable us toachieve tunable lasers with narrow linewidths. The Phase I tasks include: (1) modeling of the band structure and tuning characteristics of QCLs, (2) Molecular Beam Epitaxy (MBE) growth and materials characterization of AlInAs/InGaAs/InP laser structures,(3) fabrication and measurements of the optical spectra and tunability of QCLs, and (4) design of tunable high power QCLs based upon Bragg gratings and integrated thermo-electric heaters. For Phase II, tunable high power QCLs would be developed andcharacterized as deliverables. Improvements in emission power, laser operating temperatures, tuning range, and modulation speed would be achieved in Phase II using novel laser design, improved heat-sink packaging, and power combining methods for laserarrays. There exists an urgent need to develop trace gas sensors for detection of chemical weapons and explosives for military and homeland security applications. Infrared Absorption Spectroscopy at specific wavelengths in the 2-10mm range has beendemonstrated to provide sensitive (parts per billion) detection of chemical molecules in the atmosphere. The development of high sensitivity, low-cost QCL chemical sensors would have wide ranging applications for military and homeland security forces.The QCL-based chemical weapons sensors could be used by ground troops in hostile environments and for airborne surveillance of the battlefield. Police forces could use these chemical weapons sensors to monitor potential terrorist targets. Airport securityagents could use these chemical sensors for passenger and luggage screening. Customs agents could use these chemical sensors at ports-of-entry to detect explosives and narcotics. Also large potential commercial markets exist for environmental/industrialchemical sensing of power plant and automotive emissions and chemical waste effluent from factories. The total potential markets for QCL-based chemical sensors are estimated to exceed $100M annually by 2007.