Plasmonic Cavity Spectroscopic Polarimeter

This Small Business Technology Transfer program will develop a spectroscopic polarimeter-on-a-chip using novel plasmonic resonant cavities sensitive to linear polarization over a narrow wavelength range. Spectral selection will be possible through geometric scaling, with this work concentrating on the visible to near infrared wavelength band. Dielectric gratings with subwavelength period will act as a quarter wave plate to convert circularly polarized light into linear polarization on selected pixels. This will allow complete measurement of the polarization state with no moving parts. Detailed performance predictions will be obtained through finite element modeling (FEM) of the harmonic Maxwell’s equations. The FEM provides detailed field information, including E field, B field, energy density, and time dependent information with subwavelength resolution, which greatly aids in understanding the underlying physical mechanisms. Test structures will be made using well established nanofabrication facilities, and characterized with spectral and polarization sensitive far field techniques. Additional studies using near-field scanning optical microscopy will provide detailed information for subwavelength scale validation of the models. BENEFIT: This program will develop spectroscopic polarimeters for advanced imaging applications in visible to near IR wavelengths. However, the basic structures can readily be scaled to longer wavelengths. The plasmonic resonant cavities can be adapted for a wide range of other applications including surface enhanced RAMAN spectroscopy, optical modulators, and electric field sensors among others.