Dilute-Nitride Mid-IR (2-5 micron) Diode Lasers on InP Substrates

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0355442MawstDilute nitride compounds, such as InGaAsN, have recently enabled high performance diode lasers on GaAs substrates in the l= 1.3 mm region. The performance advantages over conventional InP-based materials are now well established; they exhibit significantly lower threshold current density with reduced temperature sensitivity compared with conventional InP-based lasers. Novel approaches are now needed to extend the emission wavelength of the dilute-nitride materials beyond 1.3 mm while maintaining high performance. While diode lasers in the 2-4 mm wavelength region have been demonstrated using GaSb- or InAs-based structures, they suffer from poor radiative efficiency and strong temperature sensitivity, allowing them to operate CW only at low temperature for wavelengths longer than 2.8 mm. New structures and active layer materials based on dilute-nitrides hold potential to achieve, efficient, room temperature CW operation in this important wavelength region. To extend emission wavelengths beyond that achievable with a conventional InGaAsN type-I QW, a new active layer structure is clearly needed. The PI proposes a novel dilute-nitride structure to access the Mid-IR (2.0 - 4.0 mm) wavelength region using conventional InP substrates. A strain-compensated, dilute-nitride active region based on In(Ga)AsN/GaAsSb type-II quantum wells is proposed. Broad Impact: Mid-IR sources, which operate efficiently at room temperature, would revolutionize chemical sensing and free-space optical communication systems. Compact chemical sensors could be developed based on this technology for real time portable detection systems. Free from atmospheric disturbances, free-space communication links could become viable from the availability of efficient, high power laser sources in the 2-4 mm region. While providing an interdisciplinary research environment for a graduate student, encompassing materials science, chemistry, advanced device modeling and optoelectronic device physics, this program integrates undergraduates into the development and execution of the research as well as providing a vehicle for new curricular materials.Intellectual merit: New dilute-nitride materials and superlattice structures will be developed, allowing us to study the optical and electronic bandstructure of these new materials and structures. A closely coupled experimental and theoretical approach will provide valuable insights into the physics of gain, carrier recombination, and carrier leakage processes in dilute-nitride type-II laser structures.