Output facet heating mechanism for uncoated high power long wave infrared quantum cascade lasers
Dagan Hathaway,
Monas Shahzad,
Tamil S. Sakthivel,
Matthew Suttinger,
Rowel Go,
Enrique Sanchez,
Sudipta Seal,
Hong Shu,
Arkadiy Lyakh
Affiliations
Dagan Hathaway
NanoScience Technology Center, University of Central Florida, 12424 Research Pkwy, Orlando, Florida 32826, USA
Monas Shahzad
NanoScience Technology Center, University of Central Florida, 12424 Research Pkwy, Orlando, Florida 32826, USA
Tamil S. Sakthivel
Department of Materials Science and Engineering and Advanced Materials Processing and Analysis Center, University of Central Florida, 12760 Pegasus Drive, Orlando, Florida 32816, USA
Matthew Suttinger
NanoScience Technology Center, University of Central Florida, 12424 Research Pkwy, Orlando, Florida 32826, USA
Rowel Go
NanoScience Technology Center, University of Central Florida, 12424 Research Pkwy, Orlando, Florida 32826, USA
Enrique Sanchez
NanoScience Technology Center, University of Central Florida, 12424 Research Pkwy, Orlando, Florida 32826, USA
Sudipta Seal
NanoScience Technology Center, University of Central Florida, 12424 Research Pkwy, Orlando, Florida 32826, USA
Hong Shu
IRGLARE, LLC, 3259 Progress Drive, Orlando, Florida 32826, USA
Arkadiy Lyakh
NanoScience Technology Center, University of Central Florida, 12424 Research Pkwy, Orlando, Florida 32826, USA
Output facet temperatures of an uncoated high power continuous-wave quantum cascade laser (QCL) emitting at 8.5 μm were measured by using micro-Raman thermometry. The rate of the measured temperature changes with the injected electrical power increased from 6.5 K/W below the laser threshold to 12.3 K/W above the threshold. In addition, the measured temperature rise exceeded 220 K at an optical power of 0.9 W, well above the model projections based only on Joule heating. Facet oxidation was characterized via x-ray photoelectron spectroscopy measurements at incremental etch depths. While the oxidation reactions of InP and Ga were observed only at the surface level, the measured penetration of native Al2O3 was ∼24 nm. COMSOL thermal modeling demonstrated that light reabsorption by the native Al2O3 layer could well explain the additional temperature rise above the threshold. These results suggest that facet oxidation must be addressed to ensure the reliability of high-power long wave infrared QCLs.
