Characterizing enhanced nonlinear optical responses in the mid-infrared spectrum

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This proposal requests funding for sensitive optical detectors in the mid-infrared (2 to 20 um) spectral range, enabling measurements of strongly enhanced nonlinear optical responses of various dielectric materials as well as the spatial, spectral and temporal tailoring of coherent thermal emission from films and time-varying metasurfaces. Specifically, funds are requested to purchase optical power detectors with associated electronics for measurements of giant ultrafast nonlinear optical responses and a sophisticated spectrometry system for detecting the thermal and spectral fingerprints of samples in the mid-IR. This necessary detection equipment for mid-IR will enable the applicants and numerous HQP to bring their nonlinear optics expertise established in the visible and near-IR regimes (400-2000 nm) into the so far largely unexplored mid-IR spectrum, where we predict light-matter interactions in phonon-mediated resonant solid state materials will reveal giant nonlinear optical enhancements, and create opportunities for thermal emission engineering.***Research enabled by this equipment is motivated by four of our recent findings: 1)nonlinear optical response of materials are greatly enhanced at near-zero permittivities due to inherent plasmonic resonances, which we have shown in near-IR; 2)prediction that the nonlinear optical properties of phononic solid state materials in the mid-IR can greatly exceed those of plasmonic ones; 3)near-zero permittivity materials can dynamically control the resonances of plasmonic and dielectric scatterers, which we have shown in near-IR; and 4)the theoretical prediction that the spatiotemporal coherence and emissivity of a blackbody can be enhanced or suppressed using near-zero permittivity. However, all experimental work has been confined to the near-IR spectrum due to the complete lack, either at uOttawa or in the NRC Ottawa facilities, of available measurement devices that are compatible with a femtosecond laser system with intense optical pulses in the mid-IR.***These specialized mid-IR optical detection systems are crucial to the expansion of the applicants' NSERC-funded research on nonlinear optics and metasurfaces from the near-IR to the mid-IR, where technological limitations have thus far prevented nonlinear optics research. The applicants hope to reveal that these distinct nonlinearities stemming from phononic resonances are even stronger than those observed at plasmonic resonances, thus providing insights into both. Furthermore, understanding large nonlinear responses based on this distinct physical phenomena could leading to the development of new coherent sources, absorbers, and signal processing devices with the potential of finding applications in thermal emission engineering of photovoltaics, optical remote detection of environmental hazards and pollutants, active-control thermal and optical camouflage and perhaps even achieving thermal emission engineering that could surpass the blackbody limit.