Highly tunable nanoscale metal-insulator-metal split ring core ring resonators (SRCRRs)

Abstract

A class of nano-scale wavelength-selective optical filters is proposed where the core of a metal-insulator-metal square ring is replaced with a split-ring core (SRC). The proposed resonator supports split-ring-resonator-like (SRR-like) resonant modes that are characteristics of the structure. These resonant modes are highly adjustable, via the gap size of the split-ring core, over a range of hundreds of nanometers. The proposed resonator can also incorporate tunable materials localized in the gap of the SRC or placed throughout the resonating path. By varying the refractive index (1 to 2) of the material in the gap of the SRC, first and second SRR-like modes can be tuned over ~200 and 300 nm, respectively. A circuit model based on transmission-line theory is proposed for the structure and used to derive the resonance conditions of the split-ring-resonator-like modes; the model compares favorably to the numerical results. The proposed resonator has the potential to be utilized effectively in integrated nano-scale optical switches and tunable filters.

Plasmon-induced transparency effect in a single circular split-ring core ring resonator side-coupled to a metal-isolator-metal waveguide

“…Based on this we can conclude that, for the TM 2.5 mode, the gap acts like a nanoinductor. 40 On the other hand, for the TM 2 mode, no magnetic field is observed in the core. Therefore, the TM 2.5 mode is sensitive to the width of the gap, while TM 2 mode remains approximately unchanged.…”

“…In order to find the resonance condition, the impedance of the split ring core must be added to the equivalent circuit. The equivalent impedance of the SRC, Z SRC , can be written as [40][41][42] …”

“…L m ¼ l 0 ð2R 2 À wÞ 2 =t is the magnetic field inductance of the SRC (t¼1 as the structure is 2D), L e ¼ Àl eff =ðx 2 e m w 0 Þ is the electron self-inductance of the SRC, and C ¼ e 0 w 0 =g is the capacitance of its gap; w 0 ¼ cw is the effective width of the SRC which is less than w due to the skin depth and the asymmetry of the current distribution between the center and the external sides of SRC (c % 0:6). [40][41][42] Z SRC is added to the transmission-line resonator as a load, which represents the symmetric mode in the ring and has a characteristic impedance of Z 0 ¼ bd=xe 0 . Due to symmetry, we have Z R ¼ Z L ¼ Z (Refs.…”

A Metal-Insulator-Metal Deep Subwavelength Cavity Based on Cutoff Frequency Modulation

“…For this reason, MIM waveguide-based cavities were proposed to realize compact devices with various structures, such as disks [17,18], rings [19,20], and blocks [21][22][23]. As the dielectric layer between metals becomes thinner, the propagating SPP mode has a larger k (wavevector), thereby miniaturizing the physical size of the photonic device [13,21,24].…”

π-Network Transmission Line Model for Plasmonic Waveguides with Cavity Structures

“…In recent years, because of their outstanding performance in subwavelength optical waveguides [3,4], surface plasmon waveguides have become a hot point. A variety of metallic structures have been proposed as waveguides in nano scale [5][6][7]. Many efforts have been made to develop nano scale metal-dielectric-metal (MDM) waveguide based on plasmonic devices.…”