Compact and Efficient Ring Resonator–Based Plasmonic Lens with Multiple Functionalities

Abstract

A novel plasmonic lens based on a metal–insulator–metal bus waveguide coupled to a ring resonator is proposed and numerically investigated. The inner edge of the ring resonator was perforated with nanogrooves so that light emitted by these nanogrooves was sharply focused at the center of the ring. The structure relies on interference and resonance theory. The principle of the lens can be extended to a device 1 × N demultiplexer as well as a 1 × N power splitter. These functionalities were validated through finite element method simulations. Results show that the lens had a sharp focus, without any smearing, and a full width at half maximum (FWHM) intensity of around 240 nm. For the 1 × N demultiplexer, the selectivity was high with an FWHM bandwidth of less than 20 nm and crosstalk of less than − 10 dB, whereas the 1 × N power splitter had a narrow bandwidth and was able to split power into N equal parts with negligible imbalance. The proposed focusing structure is compact, and the simulation results show that the structure performs the various functionalities with high efficiency. Due to this, these structures will be of utmost utility in future all-optical signal processing systems.

Visible-Range Multiple-Channel Metal-Shell Rod-Shaped Narrowband Plasmonic Metamaterial Absorber for Refractive Index and Temperature Sensing

“…A microwave frequency band of a PMA was first proposed by Landy et al in 2008 [ 19 ]. The absorption enhancement of an incident EM wave in a PMA is attributed to different patterns of mode resonances, e.g., LSPR, surface lattice resonance (SLR) [ 20 , 21 , 22 ], surface plasmon polariton resonance (SPPR) [ 23 , 24 , 25 ], gap plasmon resonance (GPR), and cavity plasmon resonance (CPR) [ 26 , 27 , 28 ]. After then, a variety of works were proposed to concern the absorptance response of a PMA working at the frequency range from a microwave [ 29 ] through terahertz (THz) [ 30 ], infrared [ 31 , 32 ], and into the visible region [ 33 , 34 , 35 ].…”