Nanoplasmonic Directional Light Sensor and Color Filter

Matthew Davis National Institute of Standards and Technology, Center for Nanoscale Science and Technology, Gaithersburg, Maryland, USA Henri Lezec National Institute of Standards and Technology, Center for Nanoscale Science and Technology, Gaithersburg, Maryland, USA Amit Agrawal National Institute of Standards and Technology, Center for Nanoscale Science and Technology, Gaithersburg, Maryland, USA

Surface plasmon polaritons (SPPs) are surface waves that exist at the interface between a metal and a dielectric resulting from coupling of electromagnetic radiation to surface charge oscillations. The study of SPPs, though easily understood with classical electromagnetics, offers a richness of phenomena that have led to a diverse range of applications in sensing, imaging, and nonlinear optics. Advances in theoretical understanding and fabrication methods have resulted in an unprecedented ability to control light through plasmonic nanostructures. For instance, enhanced transmission of light through subwavelength apertures is achieved by surrounding the aperture with nanopatterned grooves. Furthermore, periodic arrangements of the grooves results in a highly wavelength sensitive device response. Such spectral response has proven to be a useful property for color filtering in sensing, display, and imaging devices. More recently, we have demonstrated that an aperiodic slit-grooved-array (SGA) can act as a wavelength-dependent plasmonic directional light filter. This behavior is achieved through careful selection of individual groove widths, depths, and placements between the slit and the grooves. Typically, selection of groove parameters for the SGA device is achieved through time-consuming FDTD calculations. This is feasible on current desktop computers for 1D devices such as the SGA, however extending this approach to 3D plasmonic filters would benefit from a less computationally-intensive design method. In this talk, we will first present the design methodology using a 1st-order SPP interference model that is used for the filter design, a process that is free of FDTD calculations. This model is based on optimizing the phase-shift accrued by light coupling/scattering from multiple grooves surrounding a single deep-subwavelength slit. Finally, we will discuss the nanofabrication and experimental characterization of the designed nanoplasmonic filter; and demonstrate the immense time saving factor of this approach. It is expected that a passive plasmonic device sensitive to the direction of incident white light may represent a simpler approach over existing light trackers.

amit.agrawal@nist.gov









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