A novel scheme of optical readout based on thermo-optical cavity coupled plasmonic scattering for infrared detection

A novel scheme of optical readout based on thermo-optic cavity coupled plasmonic scattering for infrared imaging sensor is proposed to lessen the complex and bulky of existed systems using reflective or diffractive optical readout schemes. This new scheme readouts thermally-modulated back-scattering visible light signals of metallic nanostructures under large-angle dark field illumination. Numerical simulation is employed to reveal the mechanisms of large temperature sensitivity and low angular sensitivity of scattering, which is attributed to the thermal-optic effects of Fabry–Perot (F-P) microcavity coupled with local surface plasmon resonance (LSPR) generated from metallic nanostructures. The feasibility of the proposed scheme is demonstrated by preliminary experiments and optical measurements. Thermal-optic modulated scattering spectra have been obtained for 3.39 μm infrared illumination and a temperature sensitivity of 0.24 nm/℃ for 605 ~ 640 nm band has been reached. This scheme provides a new approach to develop compact and low cost infrared imaging systems.