Bidirectional waveguide coupling with plasmonic Fano nanoantennas

We introduce the concept of a bidirectional, compact single-element Fano nanoantenna that allows for directional coupling of light in opposite directions of a high-index dielectric waveguide for two different operation wavelengths. We utilize a Fano resonance to tailor the radiation phases of a gold nanodisk and a nanoslit that is inscribed into the nanodisk to realize bidirectional scattering. We show that this Fano nanoantenna operates as a bidirectional waveguide coupler at telecommunication wavelengths and, thus, is ideally suitable for integrated wavelength-selective light demultiplexing

A study of localized surface plasmon resonance nanoslit array and applications for chip-based protein detection

Ordered arrays of nanostructures in thin metal (Au) films have been studied for localized surface plasmon resonance (LSPR) sensing with a transmission spectral mode. We report on a nanoslit array device that is designed to permit extraordinary optical transmission (EOT) with a tunable primary peak in the visible to near infrared range and a spectral shape and light transmission that is determined by surface plasmon manipulation in the embedded gold film. Finite-difference time-domain (FDTD) simulation studies show that a nanoslit array device can provide a well-defined transmission resonance and display a monotonically increasing value of the resonance peak wavelength, ?max, with increasing period. Simulation studies show that the refractive index (RI) changes occurring on the in-slit gold surfaces contribute the most to the resonance transmission wavelength shift, suggesting that the strong confinement of LSPR in the narrow slit region is the origin of the sensitive RI response. These planar nanoslit array devices were used to detect the ligand binding protein, ß-lactoglobulin (ß-LG), with functionalization of specific binding retinals linked via a self-assembled monolayer at the array surfaces. These results illustrate the promise of nanoslit arrays for LSPR bio-detection in a lab-on-chip device platform

Investigation of Surface Plasmon Resonance in Super-Period Gold Nanoslit Arrays

Surface plasmon resonance in super-period metal nanoslits can be observed in the first order diffraction as well in the zeroth order transmission. In this paper, surface plasmon resonance modes in various super-period gold nanoslit arrays are investigated. It is found that the surface plasmon resonance frequencies are determined by the small period of the nanoslits in super-period nanoslits. The number of nanoslits in the unit cell super-period and the nanoslit width do not control the surface plasmon resonance frequencies. It is also found that the resonance wavelength observed in the first order diffraction reveals more accurate the real surface plasmon resonance wavelength in the metal super-period nanoslit array device.Comment: 14 pages, 6 figure

Integrated all-optical logic discriminators based on plasmonic bandgap engineering

Optical computing uses photons as information carriers, opening up the possibility for ultrahigh-speed and ultrawide-band information processing. Integrated all-optical logic devices are indispensible core components of optical computing systems. However, up to now, little experimental progress has been made in nanoscale all-optical logic discriminators, which have the function of discriminating and encoding incident light signals according to wavelength. Here, we report a strategy to realize a nanoscale all-optical logic discriminator based on plasmonic bandgap engineering in a planar plasmonic microstructure. Light signals falling within different operating wavelength ranges are differentiated and endowed with different logic state encodings. Compared with values previously reported, the operating bandwidth is enlarged by one order of magnitude. Also the SPP light source is integrated with the logic device while retaining its ultracompact size. This opens up a way to construct on-chip all-optical information processors and artificial intelligence systems.Comment: 4 figures 201