Metal-dielectric Waveguide Research Articles

Triple-channel glasses-shape nanoplasmonic demultiplexer based on multi nanodisk resonators in MIM waveguide

In this paper a metal-insulator-metal (MIM) plasmonic waveguide is proposed. Based on the proposed MIM waeguide and nanodisk resonators a novel 1*3 wavelength demultiplexer (WDM) structure is designed. The proposed WDM structure is based on three plasmonic filters. Each of this plasmonic filters consists of two waveguides (input and drop), and a middle cavity that are coupled with nanodisk resonators horizontally. Using these proposed plasmonic filters a three channel plasmonic demultiplexer also designed and simulated in this paper. By seting suitable values for the designed structural parameters (refractive index and geometric parameters), the structure output can be modified and adjusted in a controlled. According to the simulation results of the plasmonic demultiplexer structure, the transmission efficiency of one of the channels reaches about 80 % and The effect of cross talk is less than -23 dB. There are three different wavelengths for each channel in this proposed WDM structure. It is also notable that, 2D Finite-Difference Time-Domain (FDTD) numerical method is imployed in this paper. Large-scale photonic integration, the ultra-compact demultiplexer devices, ultra-compact demultiplexer devices, the development of optical integrated circuits and integrated plasmonic devices are among of the application that the proposed structure can be used in them.

A Microscale Numerical Analysis of Ex-OR and Ex-NOR Logic Gates by Using Single Plasmonic MZI

This work is focused on a detailed mathematical and numerical simulation–based analysis of Ex-OR and Ex-NOR logic gates at microscale by employing metal-insulator-metal (MIM) plasmonic waveguide–based Mach-Zehnder interferometer (MZI). The geometry of MIM waveguide is designed by considering the air as dielectric material in between silver metallic layers. The bulk plasma frequency and damping constant of silver metallic layers are considered as ωp = 140 × 1014 rad/s and $${\varvec{\gamma}}=$$ 0.4 × 1014 rad/s, respectively. A nonlinear Kerr-material with response in the order of picosecond is employed in linear arms of MZI to switch the phase of optical signals. The design of single MZI is modelled within the footprints of 19 × 3 µm with a high extinction ratio (ER) of 29 dB. The phase change property of MZI is utilized to validate the operation of Ex-OR and Ex-NOR gates. The results suggest that the proposed plasmonic-based logic gates can pave the path for efficient all optical signal processing system.

Optical refractive index sensor with Fano resonance based on original MIM waveguide structure

In recent years, optical refractive index sensors have received significant attention in the field of chemical and biological sensing owing to the advantages of small size. In order to achieve the requirements of small structure and high sensitivity of nano refractive index sensing, this paper proposes a Fano resonance–based waveguide structure in which a metal-insulator-metal (MIM) structure using surface plasmons and U-shaped cavities are coupled unilaterally. The transmittance spectrum of the waveguide-coupled resonator with different incident light wavelengths can be obtained. The U-shaped cavity and semi-annular straight waveguide are superimposed on and coupled to each other to form the Fano resonance transmittance spectrum. An extremely narrow impedance is formed in the transmittance spectrum. The proposed structure can obtain superior sensing performance at the nanoscale after the optimisation. The results confirm that the sensing sensitivity of the refractive index of the optimised waveguide structure can achieve up to 825 nm/RIU. The results of experiments show that this structure could accurately identify the five proposed pure edible vegetable oils at room temperature. But experiments have also shown that it could not effectively distinguish between the five proposed mixed edible vegetable oils. This structure provides an effective reference for the design and development of refractive index sensors for application to pure edible vegetable oils.

High-Q Fano Resonance in Subwavelength Stub-Wall-Coupled MDM Waveguide Structure and Its Terahertz Sensing Application

Waveguide structures effectively controlling and guiding terahertz (THz) waves can achieve interesting resonance effects when combined with resonators. At present, achieving high quality factor (Q-factor) resonance in THz resonator-coupled waveguide structure is still a critical consideration to expand its practical application. Here, a high Q-factor Fano resonance based on a metal-dielectric-metal (MDM) waveguide consisting of a stub resonator and a metal wall with an aperture in the center is investigated theoretically and numerically in the THz region. The results show that the sharp and asymmetric Fano resonance peak is induced by the destructive interference between the stub resonator and metal wall which act as a Fabry-Perot cavity. Q-factor is obviously improved about 60 times (3.72 to ~225) by introducing the metal wall into the stub-coupled MDM waveguide. Moreover, Fano resonance can be effectively tuned by varying different structure parameters. Owing to the high sensitivity of Fano resonance peak to dielectric surroundings, a large-range refractive index (RI) sensor based on the proposed structure with a high sensitivity of 96480 nm/RIU is obtained. The figure of merit (FOM) of 195 is greatly improved compared to other THz Fano-based RI sensors. These results provide possibilities for subwavelength MDM waveguide structure to apply for THz bio/chemical sensing, bandpass filters, and on-chip highly integrated plasmonic device.

Широкополосный металлодиэлектрический волноводный тракт с малыми потерями КВЧ-диапазона

. The present paper is devoted to the design of a new shielded metal-dielectric waveguide with low losses (less than 0.5 dB/m) and wide bandwidth for the 90–100 GHz frequency range. Various types of waveguide structures were analyzed, such as metal waveguides, oversized metal waveguides, dielectric waveguides, dielectric waveguides with a metal shield and various designs of the dielectric filling element. Estimates of loss per unit length in them are obtained. The design of a waveguide containing an oversized round metal screen and a dielectric element consisting of a plate and a rod, located in the center of symmetry of the device, is proposed. The task of creating a transition from the investigated waveguide to a standard rectangular metal waveguide is considered. It is a horn transition from a circular cross-section to a rectangular one with a length of more than 25 wavelengths with a dielectric structure continuing the dielectric element of the waveguide path. As a result of the work, the ratios of the dimensions of the structural elements of the waveguide path and the materials used were obtained that satisfy the required losses.

Nanoplasmonic magneto-optical isolator [Invited

We introduce a nanoplasmonic isolator that consists of a cylindrical resonator placed close to a metal-dielectric-metal (MDM) waveguide. The material filling the waveguide and resonator is a magneto-optical (MO) material, and the structure is under an externally applied static magnetic field. We theoretically investigate the properties of the structure and show that the cavity mode without MO activity splits into two modes when the MO activity is present. In addition, we find that the presence of the MDM waveguide leads to a second resonance due to the geometrical asymmetry caused by the existence of the waveguide. We also show that, when MO activity is present, the cavity becomes a traveling wave resonator. Thus, the transmission of the structure depends on the direction of the incident light, and the proposed structure operates as an optical isolator.

Integrated form of the waveguide circuits in the terahertz range

Problem statement. The successful development of the terahertz range is inextricably linked to the creation of effective guide systems with the required characteristics, as well as a complete set of functional elements. Known guide systems of the specified range for several reasons do not allow creating a complete set of functional elements and circuits for various purposes. In this paper, the authors consider the principles of creating modular waveguide circuits based on a metaldielectric waveguide.Objective. Study of the issues of creating waveguide circuits for various purposes in an integrated design. The choice of a square-section metal-dielectric waveguide is justified to solve this problem. The absence of surface currents on the walls of this waveguide dramatically reduces energy losses at the joints and flange connections. This allows for creating integrated circuits as a single module. A diagram of the high-frequency part of a monopulse locator made by pressing in plastic is given as an example.Results. It is shown that the studied design of the circuits excludes flanged connections between waveguide elements, thereby reducing losses in the connections between various functional elements, which reduces the total losses in the circuit. Experimental results are presented.Practical implications. A technology for integrated design of ultra-high-frequency terahertz circuits based on a metaldielectric waveguide, excluding flanged connections between functional elements, is proposed. This waveguide and the functional elements provide the development of various circuits for operation at high powers.

Numerical investigation of an optimized plasmonic on-chip refractive index sensor for temperature and blood group detection

A highly sensitive sensor focused on two Metal-Insulator-Metal (MIM) waveguides and three quadrilateral cavities sandwiched perpendicularly in between the MIM waveguides is proposed. Fano resonance induced by the coherent superposition of the narrow band spectral response and broadband spectral response, excites the structural transmission characteristics. The Finite Element Method (FEM) is used to numerically investigate the transmission characteristics and sensitivity of the refractive index sensor for different configurations. The linear relationship between resonant wavelength and refractive index is used to sense the materials. By optimizing the structural parameters, a numerical evaluation of the refractive index sensitivity (S) up to 1556 nm/RIU, and associate figure of merit (FOM) of 14.83 is recorded. The device is also explored as a temperature sensor with 0.61 nm/°C sensitivity. Since ethanol is used as a sensing medium, the operating range of the sensor is between −114.3 °C and 78 °C, melting and boiling temperature of ethanol. To detect human blood groups using the proposed sensor, a mathematical model is developed, which shows impressive performance for the detection of human blood groups very precisely. Compact size, ultrafine sensitivity, and sharp Fano peak profile make the proposed sensor an ideal candidate for on-chip sensors.

Study on Fano resonance sensing characteristics of double-baffle MDM waveguide coupled disk cavity with absorption material

A metal-dielectric-metal (MDM) waveguide coupled disk cavity structure with bimetallic baffle is proposed, which bases on the transmission characteristics of surface plasmon polaritons (SPPs) in subwavelength structure, and the absorption material InGaAsP is filled in the Fabry–Perot (F-P) cavity and disk cavity. The Fano resonance is an asymmetric spectral line formed by the destructive interference between the wide continuous state generated by the F-P resonator and the narrow discrete state interference generated by the disk cavity. Based on the coupled mode theory, the formation mechanism of the Fano resonance of the structure is qualitatively analyzed. The structure was simulated by finite element method to quantitatively analyze the influence of structural parameters and absorption material InGaAsP on the refractive index sensing characteristics. The proposed sensor yields sensitivity higher than 1360 nm/refractive index unit (RIU) and a figure of merit of [Formula: see text] by optimizing the geometry parameters and filling the absorption material InGaAsP. This structure has potential applications for high integration of nanosensors, slow-light devices, and nano-optical switches.

Fano resonance in a MIM waveguide with double symmetric rectangular stubs and its sensing characteristics

In this paper, a metal–insulator–metal (MIM) type surface plasmon waveguide structure is designed, which is composed of a circular split-ring resonance cavity (CSRRC) and a double symmetric rectangular stub waveguide (DSRSW). The finite element method (FEM) is used to investigate the transmission characteristics of the structure. The results show that the interference between the wide-band continuous state excited by the DSRSW and the narrow-band discrete state excited by the CSRRC produces double Fano resonances. The resonance wavelength and line shape of the Fano resonance can be tuned by the geometric parameters of the structure. After optimizing the geometric parameters, the sensitivity of the structure can be up to 1180 nm/RIU, and the figure of merit (FOM) can be up to 5585.3. Meanwhile, the structure can produce a maximum optical delay of about 0.128 ps, and the corresponding group refractive index is about 42.67. This structure has potential applications in refractive index sensors and slow light devices.

Mode coupling enhancement from dielectric to plasmonic waveguides

Efficient dielectric–plasmonic interconnect is significant in the design of future electronic–photonic integrated circuits that deal with large data transfer. We propose three designs and analysis of small-footprint couplers that are located at the interface between dielectric and plasmonic waveguides. To the best of our knowledge, our proposed couplers outperform all the works reported in the literature in several aspects including size and coupling efficiency (CE). Our results indicate that the optimum dimensions of the proposed couplers are determined based on whether the coupler is located in the metal side or dielectric side, or the coupler extends equally in both types of materials. The proposed couplers work over a broad frequency range achieving a CE above 88% at the optical communications wavelength 1550 nm. In addition, our results indicate that the CE can be further increased to above 93% by increasing the width of the dielectric waveguide before it is connected to the coupler. Moreover, our proposed designs provide a considerable alignment tolerance, which is needed when aligning the dielectric waveguide to the metal–dielectric–metal waveguide. Our proposed couplers have an impact on the design and miniaturization of nanoscale all-optical devices.

1 × 2 plasmonic wavelength demultiplexer using rectangular MIM waveguide

Abstract A 1 × 2 plasmonic demultiplexer with a rectangular metal-insulator-metal (MIM) waveguide comprising one input port and two output ports has been proposed. The proposed demultiplexer is based on the principle of interference of surface plasmon polariton waves. By placing the output port at the designed position along the rectangular MIM waveguide, the desired wavelength can be extracted from the mixture of the wavelengths. Results were simulated using finite element method (FEM) technique and plot of field and its intensity were obtained for both the wavelengths. The results agree with the proposed theory. Power transmission of more than 80% at the desired port with a suppression of more than 90% at the undesired port is obtained for both the wavelengths. A low crosstalk of less than −11.06 dB with a low insertion loss of less than 14.32 dB are measured. It is shown that the wavelength selectivity of the plasmonic demultiplexer is further dependent on the width of the MIM waveguide as well as the materials chosen. The design can be further extended to a 1×N demultiplexer by appropriate selection of position of the output ports.

Design of a Refractive Index Plasmonic Sensor Based on a Ring Resonator Coupled to a MIM Waveguide Containing Tapered Defects

In this paper, a novel nanoscale refractive index sensor topology, which incorporates a ring resonator containing circular tapered defects coupled to a metal-insulator-metal (MIM) plasmonic waveguide with tapered defects, is proposed. For the proposed design, the effect of introduction of defects on transmittance value, shape of magnetic field, and sensor parameters such as sensitivity (S) and figure of merit (FOM) are investigated numerically and simulated using finite-difference time-domain (FDTD) method. By optimizing the ring radius and selecting the appropriate waveguide width, we have achieved a maximum sensitivity of 1295 nm per refractive index unit (RIU) and a fairly high FOM equal to 159.6 RIU−1. The structure can be used as a high accuracy refractive index sensor for refractive indices ranging from 1 to 1.65. Due to the small size, wide detection range, and the high detection resolution of the proposed sensor, it is a good choice for integrated bio-sensing applications.

Sensing Features of the Fano Resonance in an MIM Waveguide Coupled with an Elliptical Ring Resonant Cavity

In this article, a novel refractive index sensor composed of a metal–insulator–metal (MIM) waveguide with two rectangular stubs coupled with an elliptical ring resonator is proposed, the geometric parameters of which are controlled at a few hundreds of nanometer size. The transmission feature of the structure was studied by the finite element method based on electronic design automation (EDA) software COMSOL Multiphysics 5.4 (Stockholm, Sweden). The rectangular stub resonator can be thought of as a Fabry–Perot (FP) cavity, which can facilitate the Fano resonance. The simulation results reveal that the structure has a symmetric Lorentzian resonance, as well as an ultrasharp and asymmetrical Fano resonance. By adjusting the geometrical parameters, the sensitivity and figure of merit (FOM) of the structure can be optimized flexibly. After adjustments and optimization, the maximum sensitivity can reach up to 1550 nm/RIU (nanometer/Refractive Index Unit) and its FOM is 43.05. This structure presented in this article also has a promising application in highly integrated medical optical sensors to detect the concentration of hemoglobin and monitor body health.

Fano resonance based on D-shaped waveguide structure and its application for human hemoglobin detection.

Fano resonance is a pervasive resonance phenomenon which can be applied to high sensitivity sensing, perfect absorption, electromagnetic-induced transparency, and slow-light photonic devices. In this paper, we propose a metal-insulator-metal (MIM) waveguide structure consisting of a D-shaped cavity and a bus waveguide with a silver-air-silver barrier. The Fano resonance can be achieved by the interaction between the D-shaped cavity and the bus waveguide. The finite element method is used to analyze the transmission characteristics and magnetic-field distributions of the structure in detail. Simulation results show the Fano resonance can be adjusted by altering the geometric parameters of the MIM waveguide structure or the refractive index of the D-shaped cavity. The maximum refractive index sensitivity of the structure can reach up to 1510 nm/RIU, and there is a good linear relationship between resonance wavelength and refractive index. Since it has good sensitivity and tunability, the MIM waveguide structure can be used in bio-sensing, such as human hemoglobin detection. We show its applicability for the detection of three different human blood groups as well.

On the resonant properties of the THz metal-dielectric waveguide impedance

Various asymptotic representations for the longitudinal monopole impedance of a two-layer metal-dielectric cylindrical waveguide with finite-conducting external walls and a lossy internal dielectric layer are derived. Areas of their applicability are determined and their properties are investigated. New features for the resonance properties of the structure under consideration are revealed and described.

Theory and FDTD simulations of an amorphous silicon planar waveguide structure suitable to be used as a surface plasmon resonance biosensor

In this paper we present our work concerning the design of a semiconductor waveguide structure to be used as a biosensor based on Surface Plasmonic Resonance effects (SPR). The proposed structure is a planar metaldielectric waveguide where the sensor operation is based on the coupling between the fundamental propagation TM mode and the surface plasmon excited at the outer boundary of the metal, which interfaces the sample medium. Gold and aluminium are the metals considered for the plasmonic coating, amorphous silicon and a reduced graphene oxide layer are considered for the waveguide structure. FDTD simulations of the proposed structure show a clear attenuation peak in the output power at the wavelength where the plasmonic resonance is excited.

Multiple Fano resonance in MIM waveguide system with cross-shaped cavity

A Metal-Insulator-Metal (MIM) waveguide structures consists of cross-shaped cavity and baffle was proposed. The simulation results show that the tunable Fano resonance existed in cross-shaped cavity structures by adjusting the length parameters of horizontal and vertical cavities. Further, the position and alignment of the resonant peak wavelength can be easily changed. The sensitivity of the structure is up to 1075 nm/RIU and the figure of merit (FOM) is 9.95 × 104 by changing the parameters of structure. However, for improved double cross-shaped cavity structure, a linear refractive index sensitivity of 1100 nm/RIU with a figure of merit of about 1.08 × 105 can be obtained. The results clarified that the developed structure could have a great potential in nanosensor and spectral splitter.

MIM waveguide structure consisting of a semicircular resonant cavity coupled with a key-shaped resonant cavity.

We describe the optical transmission properties of a surface plasmon polariton waveguide structure consisting of a metal-insulator-metal (MIM) waveguide and a semicircular resonant cavity coupled with a key-shaped resonant cavity. Finite element algorithm simulated the optical response of a MIM waveguide structure. The influence of coupling length, geometrical size, and asymmetry of the key-shaped cavity and the radius of the semicircular resonant cavity on the Fano resonance line was investigated. Results demonstrate that variation of the key-shaped cavity asymmetry leads to the appearance of dual Fano resonances. When materials with different refractive index fill in the key-shaped cavity, the MIM waveguide structure achieves a sensitivity of 1261.67 nm/RIU. This performance allows the waveguide to be used for nanoscale biosensor applications such as measuring glucose concentrations. We simulated various spiked glucose concentrations by calculating the frequency shift as the second Fano resonance line moves towards longer wavelength. Glucose concentrations were calculated from variations of the Fano resonant wavelength. The waveguide structure proposed in this paper shows impressive practical prospects for many applications in the chemical sensing and biomedical fields.

High-sensitivity Fano resonance temperature sensor in MIM waveguides coupled with a polydimethylsiloxane-sealed semi-square ring resonator

A compact Fano resonance temperature sensor is proposed in this paper. The sensor consists of two metal-insulator-metal (MIM) waveguides and a side-coupled polydimethylsiloxane (PDMS)-sealed semi-square ring resonator. We numerically investigate the transmission characteristics of the plasmonic structure to assess the optical properties of the sensor with the finite element method (FEM) and obtained great optical performance. The simulation results show that a sharp transmission-reflection profile can be observed in the transmission spectra and the Fano resonances curves exhibit different responses to the variations of structural parameters and ambient temperature. Due to the high thermal-optic coefficient of PDMS, the proposed sensor has an outstanding sensitivity, as high as −4 nm/°C. Our research also demonstrates that the device has the advantage of low dissipation loss due to the high Q factor. The sensor offers the prospect of development of practical applications for high sensitivity temperature-measurement.