title: Simple Nanoimprinted Polymer Nanostructures for Uncooled Thermal Detection by Direct Surface Plasmon Resonance Imaging.
abstract: We experimentally demonstrate the uncooled detection of long wavelength infrared (IR) radiation by thermal surface plasmon sensing using an all optical readout format. Thermal infrared radiation absorbed by an IR-sensitive material with high thermo-optic coefficient coated on a metal grating creates a refractive index change detectable by the shift of the supported surface plasmon resonance (SPR) measured optically in the visible spectrum. The interface localization of SPR modes and optical readout allow for submicrometer thin film transducers and eliminate complex readout integrated circuits, respectively, reducing form factor, leveraging robust visible detectors, and enabling low-cost imaging cameras. We experimentally present the radiative heat induced thermo-optic action detectable by SPR shift through imaging of a thermal source onto a bulk metal grating substrate with IR-absorptive silicon nitride coating. Toward focal plane array integration, a route to facile fabrication of pixelated metal grating structures by nanoimprint lithography is developed, where a stable polymer, parylene-C, serves as an IR-absorptive layer with a high thermo-optic coefficient. Experimental detection of IR radiation from real thermal sources imaged at infinity is demonstrated by our nanoimprinted polymer-SPR pixels with an estimated noise equivalent temperature difference of 21.9 K.
authors.affiliation: Ultrafast and Nanoscale Optics, Department of Electrical Engineering, University of California , San Diego, California 92093, United States.
authors.forename: Brandon
authors.identifier: http://orcid.org/0000-0002-4800-1040
authors.initials: B
authors.lastname: Hong
authors.affiliation: Ultrafast and Nanoscale Optics, Department of Electrical Engineering, University of California , San Diego, California 92093, United States.
authors.forename: Felipe
authors.initials: F
authors.lastname: Vallini
authors.affiliation: Ultrafast and Nanoscale Optics, Department of Materials Science & Engineering, University of California , San Diego, California 92093, United States.
authors.forename: Cheng-Yi
authors.initials: CY
authors.lastname: Fang
authors.affiliation: Center of Excellence for Telecommunication King Abdulaziz City for Science and Technology , Riyadh 12371, Saudi Arabia.
authors.forename: Amr
authors.initials: A
authors.lastname: Alasaad
authors.affiliation: Ultrafast and Nanoscale Optics, Department of Electrical Engineering, University of California , San Diego, California 92093, United States.
authors.forename: Yeshaiahu
authors.initials: Y
authors.lastname: Fainman
keywords: nanoimprint; parylene; surface plasmon resonance; surface plasmon resonance imaging; thermo-optic effect; uncooled infrared detection