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Enhanced Emission from Ultra-Thin Long Wavelength Infrared Superlattices on Epitaxial Plasmonic Materials

Molecular beam epitaxy allows for the monolithic integration of wavelength-flexible epitaxial infrared plasmonic materials with quantum-engineered infrared optoelectronic active regions. We experimentally demonstrate a six-fold enhancement in photoluminescence from ultra-thin (total thickness of 1/32-th wavelength) long wavelength infrared (LWIR) superlattices grown on highly doped semiconductor designer metal virtual substrates when compared to the same superlattice grown on an undoped virtual substrate. Analytical and numerical models of the emission process via a Dyadic Greens function formalism are in agreement with experimental results and relate the observed enhancement of emission to a combination of Purcell enhancement due to surface plasmon modes as well as directionality enhancement due to cavity-substrate-emitter interaction. The results presented provide a potential path towards efficient, ultra-subwavelength LWIR emitter devices, as well as a monolithic epitaxial architecture offering the opportunity to investigate the ultimate limits of light-matter interaction in coupled plasmonic/optoelectronic materials.