Angle-mdulated single-pixel plasmonic color filter

We demonstrate the design, simulation and experimental realization of a single-pixel aperiodic slit-groove plasmonic device that exhibits angle-selectable RGB color response at optical frequencies. The structure demonstrates high quality-factor and optical contrast with full-color RGB response. Surface plasmon polaritons (SPPs) are surface waves at a metal and dielectric interface resulting from the coupling of electromagnetic radiation to charge oscillations. The study of SPPs, though easily understood with classical theory, offers a richness of phenomena that has led to a diverse range of applications in sensing, imaging, and non-linear optics [1]. In recent years, plasmonic based structures exhibiting a full-color RGB response have been developed, however these devices require the fabrication of three physically separate structures with scaled periodicities each tailored to a single frequency [2–4]. Here, we demonstrate the design, fabrication and experimental characterization of a single aperiodic slit-groove based plasmonic device that exhibits angle-selectable RGB color response with high-Q and high optical contrast at optical frequencies. The device consists of a single-subwavelength slit surrounded by multiple grooves whose position, widths and depths are individually optimized to exhibit the desired color response at specific incident angles (Fig. 1(b) and (c)). In this talk, we will discuss how the optimization method as proposed here could be utilized to fabricate high-Q slit-groove plasmonic structures for sensing applications. A simple-interference based 1st-order analytical model that is used for a filter design process, and free of FDTD calculations, will also be discussed. This model is based on optimizing the phase-shift accrued by light coupling/scattering from multiple grooves surrounding a single deep-subwavelength slit. Besides its simplicity and accuracy in predicting the spectral transmission (Fig. 1(b)), the plasmonic filter design model represents immense time saving factor during the filter design process. We will finally discuss a three-dimensional directional light sensor produced by this model. We expect this design process and optimization algorithm to be applicable to a number of other plasmonic and photonic device designs. This reverse-engineering approach of designing structures holds promise for next generation aperiodic nanophotonic devices.