Midwave Infared (MWIR) Quantum Cascade Lasers (QCL) Thermal Monitoring

Max-IR Labs LLC, in collaboration with UT Dallas, successfully demonstrated construction and operation of a prototype Infrared Near-Field Scanning Optical Microscopy (IR-SNOM) instrument for high-spatial-resolution thermal mapping of small heat sources, in particular Quantum Cascade Laser (QCL) facets, during Phase I.Preliminary data demonstrated feasibility of implementation of this instrument and method, employing several innovations, for the measurement/mapping of thermal signals from QCLs. Based on principles of near-field optics, the instrument implements a tapered infrared fiber with a sub-wavelength aperture as a sensor element that enables measurements over large temperature ranges with sub-wavelength spatial resolution.Phase II of this STTR project will focus on improvement of signal-to-noise ratio (SNR), automated near-field probe positioning, advanced measurement schemes for improved differentiation between thermal signals and IR signals emitted by QCLs, and on thermal modeling of QCLs. Testing and characterization of the IR-SNOM instrument during Phase II will focus on research into thermal effects that can have a significant impact on a laser's optical performance and reliability, and on understanding potential failure mechanisms. Collected data will be compared with simulated thermal signals based on thermal modeling, exploring influences of mounting configuration, ridge geometry and coating design on the thermal performance of QCLs.