Enhancement of Second Harmonic Generation in Metal-Insulator-Metal Plasmonic Waveguides

Nonlinear effects such as second harmonic generation (SHG) are important for applications such as switching and wavelength conversion. In this study, the generation of second harmonic in metal-insulator-metal (MIM) plasmonic waveguides was investigated for both symmetric and asymmetric structures. This study considered two different structures as plasmonic waveguides for the generation of second harmonic, and analysis was performed using the finite-difference time-domain method. Besides, the structure has grating on both sides for more coupling between photons and plasmons. The wavelength duration of grating per unit length (number of grooves) was optimized to reach the highest second harmonic generation. To perform this optimization, the wavelength of operation (λ = 458 nm) was considered. It was shown that field enhancement in symmetric MIM waveguides can result in the enhancement of SHG magnitude when compared to literature values. Also, asymmetric devices result in more than two orders of magnitude enhancement in SHG, as compared to the symmetric structure. It has been shown that the electric field of the second harmonic depends on the thickness of the crystal (insulator). Hence, its thickness was optimized to achieve the highest electric field.     

Investigation of Second Harmonic Generation in Asymmetric Metal-Insulator-Metal Plasmonic Waveguides

Plasmonics - In this study, the second harmonic generation in metal-insulator-metal (MIM) plasmonic waveguides was investigated for both symmetric and asymmetric structures. Nonlinear processes...     

Plasmonic Filter Using Metal-Insulator-Metal Waveguide with Phase Shifts and its Transmission Characteristics

Plasmonics - A plasmonic filter based on metal-insulator-metal (MIM) waveguide with phase shifts is proposed, and the corresponding transmission characteristics are investigated. Since the...     

Analysis and Optimum Design of Hybrid Plasmonic Slab Waveguides

Propagation properties of hybrid plasmonic slab waveguides are studied in detail using transfer matrix method considering structural and material aspects. Hybrid metal–insulator, hybrid metal–insulator–metal, and hybrid insulator–metal–insulator waveguides are considered. Propagation length (L _p), spatial length (L _s), and mode length (L _m) are utilized as three common figures of merit to compare and optimize the waveguides according to the layer thicknesses and metal/dielectric materials. The effect of constituting materials including metals (such as silver, gold, copper, and aluminum) and dielectrics (common dielectric materials used in photonic integrated circuit technologies such as silicon and silicon compounds, III–V compounds, and polymers) are discussed. It is found that hybrid waveguides are partially to completely superior to conventional plasmonic waveguides, providing a better balance between confinement and loss.     

Design of a Single-Mode Plasmonic Bandpass Filter Using a Hexagonal Resonator Coupled to Graded-Stub Waveguides

Plasmonics - In this paper, a plasmonic filter based on metal-insulator-metal (MIM) configuration is proposed. It uses a hexagonal nano-resonator (HNR) coupled to multi-stub waveguides (MSWs) from...     

Multiple-Channel Plasmonic Filter Based on Metal-Insulator-Metal Waveguide and Fractal Theory

Plasmonics - A multiple-channel plasmonic filter based on metal-insulator-metal waveguide and fractal theory is proposed. The sandwiched insulator layer is constructed by a series of dielectrics...     

Plasmonic Slot Waveguides with Core Nonlinearity

We analytically study the interplay between group velocity dispersion and material dispersion due to femtosecond ultrafast pulse inside plasmonic slot waveguides with nonlinear dielectric core. The analytic investigation of the role of the core nonlinearity on pulse propagation has been investigated. Interestingly, our model shows that the focusing and defocusing effects of the material can be revered if the material is confined inside the core of a plasmonic slot. We confirm our analytical results with nonlinear finite difference time domain (FDTD) simulations.     

High-Performance Tunable Plasmonic Absorber Based on the Metal-Insulator-Metal Grating Nanostructure

Plasmonics - A new high-performance plasmonic absorber based on the metal-insulator-metal grating nanostructure is proposed and numerically studied. The effect of geometric parameters of grating...     

Graphene-Based Plasmonic Waveguides: a Mini Review

Plasmonics - Graphene plasmonics is one of the most explored fields since the successful experimental discovery of the graphene due to its unprecedented properties. The dynamical modulation and...     

Plasmonic Directional Couplers Based on Multi-Slit Waveguides

We propose and investigate the performance of the plasmonic directional couplers based on two dimensional multi-slit plasmonic waveguides, employing the finite difference time domain simulation method. The idea behind the directional properties of the directional couplers is the interference of two wave components, in and out of phase, at the coupled and isolated ports, respectively. The coupler is also analyzed by an analytic method. The simulation results comply well with those of the analytic considerations. The effects of variations of the coupler structural parameters, crosstalk between the input and output ports, and the overall structure loss are also investigated.     

Magneto-Optic Effects in Subwavelength Nonlinear Plasmonic Waveguides

Plasmonics - We report a new type of magneto-optic effect in nonlinear metamaterial waveguides, composed of an array of split ring resonators (SRRs) with varactors. The results show that there...     

Modelling of Polarization-Dependent Loss in Plasmonic Nanowire Waveguides

We have investigated the potential of using gold nanowires embedded in a dielectric cladding environment as polarization-independent long-range surface plasmon polariton waveguides at telecom wavelengths. We performed finite-element analysis on various symmetric and close-to-symmetric cross-sectional geometries and evaluated the effects of cladding thickness on the propagation and coupling loss. The calculations confirm that fabrication of polarization-independent waveguides with reasonable tolerances is feasible and that straight-waveguide insertion losses around 1.5 dB for short (0.5 mm) devices can be realized when coupling to and from conventional dielectric waveguide geometries.     

Ultra-Broadband Excitations of Plasmonic Waveguides by Bowtie Apertures

Plasmonics - The plasmonic bowtie antenna constantly attracts researchers’ interests recently. In this paper, we design and demonstrate polarization sensitive and ultra-broadband excitations...     

Multi-mode Hybrid Plasmonic Waveguides with Enhanced Confinement and Propagation

A hybrid waveguide, which consists of a dielectric wire above a dielectric-metal interface, has been previously proposed to achieve high confinement with low loss. By exciting this geometry with an aperture in the metal that takes advantage of the extraordinary transmission through subwavelength apertures, it is possible to strongly couple to multiple modes. The real part of the fundamental mode is in fact capable of exceeding the index of refraction of all the materials used while maintaining a manageable imaginary part, as a result of appropriate choice of materials for the dielectric wire and the metal. In addition, as the confinement of the second mode is comparable to that of the fundamental mode but has a much longer propagation length, this mode can be utilized in light-guiding applications where enhanced confinement and propagation is desired.     

Spatial Nonlinearity in Anisotropic Metamaterial Plasmonic Slot Waveguides

Plasmonics - We study the main nonlinear solutions of plasmonic slot waveguides made from an anisotropic metamaterial core with a positive Kerr-type nonlinearity surrounded by two semi-infinite...     

Tunable Multiple Fano Resonances and Stable Plasmonic Band-Stop Filter Based on a Metal-Insulator-Metal Waveguide

Plasmonics - A metal-insulator-metal (MIM) waveguide consisting of two stub resonators and a ring resonator is proposed, which can be used as refractive index sensor and stop-band filter at the...     

Design and Optimization of Open-cladded Plasmonic Waveguides for CMOS Integration on Si3N4 Platform

Herein, we present a design analysis and optimization of open-cladded plasmonic waveguides on a Si₃N₄ photonic waveguide platform targeting CMOS-compatible manufacturing. For this purpose, two design approaches have been followed aiming to efficiently transfer light from the hosting photonic platform to the plasmonic waveguide and vice versa: (i) an in-plane, end-fire coupling configuration based on a thin-film plasmonic structure and (ii) an out-of-plane directional coupling scheme based on a hybrid slot waveguide. A comprehensive numerical study has been conducted, initially deploying gold as the reference metal material for validating the numerical models with already published experimental results, and then aluminum and copper have been investigated for CMOS manufacturing revealing similar performance. To further enhance coupling efficiency from the photonic to the plasmonic part, implementation of plasmonic tapering schemes was examined. After thorough investigation, plasmo-photonic structures with coupling losses per single interface in the order of 1 dB or even in the sub-dB level are proposed, which additionally exhibit increased tolerance to deviations of critical geometrical parameters and enable CMOS-compatible manufacturing.

     

Design of Plasmonic Comb-Like Filters Using Loop-Based Resonators

A subwavelength plasmonic comb-like filter is proposed by using dual symmetric slot cavities which are placed between two parallel metal–insulator–metal (MIM) structure waveguides. The structure can be considered as a resonance loop which consists of slot cavity resonators and MIM waveguide resonators. The reflective wavelength range and channel spacing are determined by the lengths of slot cavities and MIM waveguides, respectively. Three, four, and five reflective channels with high reflection are achieved in a small wavelength range. Higher channel count can be available by increasing the length or the real part of effective index of MIM waveguides. Such a device can find applications in various optical systems such as wavelength demultiplexing components.     

A High Performance Plasmonic Sensor Based on Metal-Insulator-Metal Waveguide Coupled with a Double-Cavity Structure

A high performance plasmonic sensor based on a metal-insulator-metal (MIM) waveguide coupled with a double-cavity structure consisting of a side-coupled rectangular cavity and a disk cavity is proposed. The transmission characteristics of the rectangular cavity and disk cavity are analyzed theoretically and the improvements of performance for the double-cavity structure compared with a single cavity are studied. The influence of structural parameters on the transmission spectra and sensing performance are investigated in detail. A sensitivity of 1136 nm/RIU with a high figure of merit of 51,275 can be achieved at the resonant wavelength of 1148.5 nm. Due to the high performance and easy fabrication, the proposed structure may be applied in integrated optical circuits and on-chip nanosensors.     

Coherent-Controlled All-Optical Devices Based on Plasmonic Resonant Tunneling Waveguides

Plasmonics - In this study, the signal processing in three-port and four-port plasmonic coupler devices by coherently controlling the phases and amplitudes of launched surface plasmons is...