Showing papers on "Stub (electronics) published in 2016"

Experimental investigation on stub-column behavior of cold-formed high-strength steel tubular sections

Abstract: This paper presents the experimental investigation on the compressive behavior of cold-formed high-strength steel tubular stub columns. In this paper, the nominal 0.2% proof stress of the high-strength steel was 700, 900, and 1,100 MPa. A total of 25 stub column tests on circular, rectangular, and square hollow structural sections were conducted. Geometric imperfections and load-deformation histories were reported and assessed. The experimental results were compared against the design values calculated from the Australian, European, and North American codes, and the corresponding compactness criteria were assessed. A finite-element model, which incorporated the varying material properties, was described, and the influence of geometric and material imperfections was also evaluated. The finite-element results successfully captured the experimental observations and can be adopted for future parametric studies.

Waveguide-Fed Tunable Metamaterial Element for Dynamic Apertures

Abstract: We present the design of a tunable metamaterial element that can serve as the building block for a dynamically reconfigurable aperture. The element-a complimentary electric-LC (cELC) resonator-is patterned into the upper conductor of a microstrip transmission line, providing both a means of exciting the radiating metamaterial element as well as independent access for biasing circuitry. PIN diodes are connected across the capacitive gaps of the cELC, and a dc bias current is used to switch the junction between conducting and insulating states. The leakage of RF signal through the bias line is mitigated by integration of a radial decoupling stub. The proposed design and operation of the element are demonstrated through full-wave electromagnetic simulations. We discuss the potential application of the cELC element as a building block for metamaterial apertures capable of dynamic beamforming, imaging, or security screening applications.

Theoretical analysis of ultrahigh figure of merit sensing in plasmonic waveguides with a multimode stub

Abstract: We propose an expanded coupled mode theory to analyze sensing performance in a plasmonic slot waveguide side-coupled with a multimode stub resonator. It is confirmed by the finite-difference time-domain simulations. Through adjusting the parameters, we can realize figure of merit (FOM) of ∼59,010, and the sensitivity S can reach to 75.7. Compared with the plasmonic waveguide systems in recent Letters, our proposed structure has the advantages of easy fabrication, compactness, sensitivity, and high FOM. The proposed theory model and findings provide guidance for fundamental research of the integrated plasmonic nanosensor applications.

Composite action of octagonal concrete-filled steel tubular stub columns under axial loading

Abstract: Four groups of axial compression tests on hexagonal CFT stub columns have been carried out aiming to investigate the effects of the concrete strength and steel ratio on the behaviour of hexagonal CFT stub columns. Studies on parametric analysis and composite action between core concrete and steel tube have been carried out using FE modelling which had been benchmarked using the test data. Based on the essential data obtained in this paper, the ratio of axial stress-yield strength of steel tube was determined at the ultimate state. The stress contour of core concrete was simplified to an unconfined area without constraint and a confined area with uniform constraint imposed by hexagonal steel tube. Eventually, a practical design equation of the ultimate bearing capacity of hexagonal CFT stub columns was proposed based on the superposition principle. An excellent agreement between the proposed equation and the experimental results was observed, with an average ratio of predicted to measured capacity of 1.08 and a standard deviation of 0.05.

Fano resonances in a plasmonic waveguide system composed of stub coupled with a square cavity resonator

Abstract: A coupled plasmonic waveguide resonator system which can produce sharp and asymmetric Fano resonances was proposed and analyzed Two Fano resonances are induced by the interactions between the narrow discrete whispering gallery modes in a plasmonic square cavity resonator and the broad spectrum of the metal–insulator–metal stub resonator The relative peak amplitudes between the 1st and 2nd order Fano resonances can be adjusted by changing the structure parameters, such as the square cavity size, the stub size and the center-to-center distance between the square cavity and the stub resonators And the 1st order Fano resonant peak, which is a standing-wave mode, will split into two resonant peaks (one standing-wave mode and one traveling-wave mode) when it couples with the 2nd Fano resonance Also, the potential of the proposed Fano system as an integrated slow-light device and refractive index sensor was investigated The results show that a maximum group index of about 100 can be realized, and a linear refractive index sensitivity of 938 nm/RIU with a figure of merit of about 135 × 104 can be obtained

Comparative study of square stirrup-confined concrete-filled steel tubular stub columns under axial loading

Abstract: This paper presents a comparative study and a 3D finite element (FE) model of square stirrup-confined concrete-filled steel tubular (stirrup-confined CFT) stub columns. The FE results agreed well with the experimental results. The results indicated that: (1) The ultimate load-bearing capacity of CFT stub columns with internal studs was no improvement; (2) All three forms of stirrup confinement effectively reduced local bucking of the steel tube, and the cross ties was optimal, followed by spiral stirrups; (3) With the same overall steel ratio, the behavior of the square stirrup-confined CFT stub columns was considerably higher than in the square CFT stub columns.

Design of a Compact Ultra-Wideband Bandpass Filter With an Extremely Broad Stopband Region

Abstract: This letter presents a design of a compact ultra-wideband (UWB) bandpass filter (BPF), which can exhibit an UWB response from 3.1 to 9.9 GHz with low insertion loss (IL) of 0.8 dB and an extremely broad stopband region from 10.9 to 25.1 GHz with high rejection level of 20 dB. This UWB BPF is simply constructed by using only one single-stage parallel-coupled line and two rectangular stub resonators. In this design, the rectangular stub resonators provide an exciting mode to enhance the desired UWB response and also create tunable transmission zeros to extend a wide stopband by controlling the impedance ratio $(R)$ properly. The filter was fabricated and measured to verify the design concept.

Tunable ultra-wide band-stop filter based on single-stub plasmonic-waveguide system

Abstract: A nanoscale plasmonic filter based on a single-stub coupled metal–dielectric–metal waveguide system is investigated theoretically and numerically. A tunable wide band-stop can be achieved by loading a metal bar into the stub. The band-stop originates from the direct coupling between the resonance modes. The bandwidth and the center wavelength of the band-stop can be tuned by changing the parameters of the metal bar. Compared with previously reported filters, the plasmonic system has the advantages of easy fabrication and compactness. Our results indicate that the proposed system has potential to be utilized in integrated optical circuits and tunable filters.

A Four-Band Rectifier With Adaptive Power for Electromagnetic Energy Harvesting

Abstract: This letter presents a novel adaptive power rectifier operating at four bands to harvest the electromagnetic energy in the low and wide-range power density conditions. The power range of the rectifier is extended by two operation modes controlled adaptively by a FET switch according to the input power level. A cross-shaped match stub connected by a stepped impedance microstrip line is designed to make the rectifier work at four bands. Two cascaded radial open stubs act as a dc-pass filter to block the fundamental frequency wave and the high order harmonics to further improve the RF-DC (radio frequency-direct current) efficiency, and to smooth the output dc power. When the input power level is −10dBm, the measured maximum RF-DC efficiencies are 47.8%, 33.5%, 49.7% and 36.2% at the frequencies of 0.89GHz, 1.27GHz, 2.02GHz and 2.38GHz, respectively. The efficiency is above 30% in every band when the input power is from −12dBm to 12dBm, which shows a wide input power range.

Differential Dual-Band Bandpass Filter With Tunable Lower Band Using Embedded DGS Unit for Common-Mode Suppression

Abstract: This paper presents a varactor- and stub-loaded dumbbell-shaped resonator (VSDSR) for application in differential dual-band bandpass filter, which possesses a tunable lower passband and a fixed upper passband. Under differential-mode (DM) bisection, the VSDSR behaves as a ring resonator with four resonant modes, which can be categorized into two independent groups for constructing two passbands. At the same time, the common-mode (CM) equivalent circuit of the VSDSR generates multiple CM resonant frequencies and some of them inevitably overlap with the DM ones. Accordingly, the traditional CM suppression methods such as adding shunt stub or lumped element are disabled. To suppress the CM signals in both DM passbands, the defected ground structure (DGS) units are embedded underneath the adjacent edges of the two rings directly to form a CM suppression filter without increasing the circuit size. Meanwhile, they have almost no effect on the DM responses. Benefitting from the bandstop and slow-wave effects of the employed DGS units, the CM noises in both DM bands can be rejected effectively. In particular, the level of the CM suppression in the DM lower passband can be improved by adjusting the location of the DGS units. Furthermore, the proposed CM suppression scheme is adaptive in the tunable lower DM passband.

Effect of friction on axially loaded stub circular tubed columns

Abstract: This article discusses the influence of bond and friction between the steel tube and concrete on composite response for circular tubed-reinforced-concrete short columns under axial compression. Thi...

Design of multi-band bandpass filters based on stub loaded stepped-impedance resonator with defected microstrip structure

Abstract: The design of multi-band bandpass filters (BPFs) employing stub loaded stepped-impedance resonator with defected microstrip structure (SL-SIR-DMS) is presented in this study for the first time. The proposed SL-SIR-DMS is created by embedding DMS on the low-impedance line of the SL-SIR. It is found that different defected structures can lead to different frequency responses. In addition, by using DMS, tri-band and even quad-band responses can be easily achieved without increasing the resonator size. As verification, one tri-band SL-SIR-DMS and one quad-band SL-SIR-DMS are designed and analysed using even/odd-mode method. Subsequently, one tri-band BPF and one quad-band BPF have been developed with pseudo-interdigital coupling to realise good out-of-band performance. The predicted results are compared with measured ones and good agreement is achieved. Compared with BPFs using only SL-SIR, the proposed filters with DMS are more compact due to the slow-wave characteristic. Compared with the BPFs using defected ground structure to improve the stopband performance, the proposed ones can realise comparable wide stopbands but maintaining the signal integrity on the ground plane for packaging purpose.

Large diameter concrete-filled high strength steel tubular stub columns under compression

Abstract: Experimental and numerical investigations on three large diameter concrete-filled high strength steel tubular (CFHSST) stub columns under axial compression were performed. The three large size steel tubes had the same dimension in the test. The outer diameter was approximately 550 mm, the length was approximately 1000 mm, and the thickness was approximately 16 mm. The steel tubes were made of high strength steel Q550 and filled with C30 concrete. A 40,000 kN press machine was adopted to apply the required axial compression to the three specimens. It was found that the load-displacement curves of the three concrete-filled high strength circular steel tubular stub columns were notably close to each other, and the ultimate capacities were approximately 30,000 kN. Finite element analysis (FEA) was performed to analyze the stub columns, and the FEA results are consistent with the experimental results. The formulas from three types of design codes were used to calculate the column loading capacity, and the calculation results were compared with the experimental results. The results were close to the experimental results. The EC4 design code gives the most accurate estimations, with discrepancy less than 4% being observed.

Compact Dual-Band Filter Using Open/Short Stub Loaded Stepped Impedance Resonators (OSLSIRs/SSLSIRs)

Abstract: A novel microstrip dual-band filter with high frequency selectivity and extended rejection band is reported in this letter. The proposed filter employs one pair of open stub loaded stepped impedance resonators (OSLSIRs) functioning at two frequencies of interest. Two short stub loaded stepped impedance resonators (SSLSIRs) are embedded between the coupled OSLSIRs to generate quasi-elliptic response at two diverse frequencies. Contributed by the 0° feed structure, extra transmission zeros are produced to enhance the out-of-band rejection. OSLSIRs/SSLSIRs are chosen to achieve desired in-band performance and misaligned harmonic frequencies simultaneously. To demonstrate the efficacy of the design concept, a dual-band filter centering at 1.63 and 2.73 GHz is implemented. The design methodology and measured results are presented.

Broadband near total light absorption in non-PT-symmetric waveguide-cavity systems.

Abstract: We introduce broadband waveguide absorbers with near unity absorption. More specifically, we propose a compact non-parity-time-symmetric perfect absorber unit cell, consisting of two metal-dielectric-metal (MDM) stub resonators with unbalanced gain and loss side-coupled to a MDM waveguide, based on unidirectional reflectionlessness at exceptional points. With proper design, light can transport through the perfect absorber unit cell with reflection close to zero in a broad wavelength range. By cascading multiple unit cell structures, the overall absorption spectra are essentially the superposition of the absorption spectra of the individual perfect absorber unit cells, and absorption of ~ 100% is supported in a wide range of frequencies.

Stub-Loaded Theory and Its Application to Balanced Dual-Band Bandpass Filter Design

Abstract: Novel stub-loaded theory is presented and applied to design balanced dual-band bandpass filter with independently controlled passband frequencies and bandwidths. According to the presented stub-loaded theory, the first differential-mode resonance can be independently designed by the loaded stubs, while not affecting the second one. Besides, except for the main coupling path, one more coupling path between the loaded stubs can be used to independently control the coupling coefficient of the first passband. Therefore, both the passband frequencies and bandwidths of each differential passband can be easily designed. To validate the proposed idea, the balanced dual-band BPF is designed, simulated and measured. Simulated and measured results are well agreed.

Submillimeter-Wave 3.3-bit RF MEMS Phase Shifter Integrated in Micromachined Waveguide

Abstract: This paper presents a submillimeter-wave 500–550-GHz MEMS-reconfigurable phase shifter, which is based on loading a micromachined rectangular waveguide with 9 E-plane stubs. The phase shifter uses MEMS-reconfigurable surfaces to individually block/unblock the E-plane stubs from the micromachined waveguide. Each MEMS-reconfigurable surface is designed so that in the nonblocking state, it allows the electromagnetic wave to pass freely through it into the stub, while in the blocking state, it serves as the roof of the main waveguide and blocks the wave propagation into the stub. The phase-shifter design comprises three micromachined chips that are mounted in the H-plane cuts of the rectangular waveguide. Experimental results of the first device prototypes show that the microelectromechanical system (MEMS)-reconfigurable phase shifter has a linear phase shift of 20 $\mathbf {^{\circ }}$ in ten discrete steps (3.3 bits). The measured insertion loss is better than 3 dB, of which only 0.5–1.5 dB is attributed to the MEMS surfaces and switched stubs, and the measured return loss is better than 15 dB in the design frequency band of 500–550 GHz. It is also shown that the major part of the insertion loss is attributed to misalignment and assembly uncertainties of the micromachined chips and the waveguide flanges, shown by simulations and reproducibility measurements. The MEMS-reconfigurable phase shifter is also operated in an analog tuning mode for high phase resolution. Furthermore, a detailed study has been carried out identifying the reason for the discrepancy between the simulated (90 $\mathbf {^{\circ }}$ ) and the measured (20 $\mathbf {^{\circ }}$ ) phase shift. Comb-drive actuators with spring constant variations between 2.13 and 8.71 N/m are used in the phase shifter design. An actuation voltage of 21.94 V with a reproducibility better than $\mathbf {\sigma }=$ 0.0503 V is measured for the actuator design with a spring constant of 2.13 N/m. Reliability measurement on this actuator was performed in an uncontrolled laboratory environment and showed no deterioration in the functioning of the actuator observed over one hundred million cycles.

Dual-band RFID tag antenna based on the Hilbert-curve fractal for HF and UHF applications

Abstract: A novel single-radiator card-type tag is proposed which is constructed using a series Hilbert-curve loop and matched stub for high frequency (HF)/ultra high frequency (UHF) dual-band radio frequency identification (RFID) positioning applications. This is achieved by merging the series Hilbert-curve for implementing the HF coil antenna, and square loop structure for implementing the UHF antenna to form a single RFID tag radiator. The RFID tag has directivity of 1.75 dBi at 25 MHz, 2.65 dBi at 785 MHz, 2.82 MHz at 835 MHz and 2.75 dBi at 925 MHz. The tag exhibits circular polarisation with −3 dB axial-ratio bandwidth of 14, 480, 605 and 455 MHz at 25, 785, 835 and 925 MHz, respectively. The radiation characteristics of the RFID tag is quasi-omnidirectional in its two orthogonal planes. Impedance matching circuits for the HF/UHF dual-band RFID tag are designed for optimal power transfer with the microchip. The resulting dual-band tag is highly compact in size and possesses good overall performance which makes it suitable for diverse applications.

Ultra Sharp Fano Resonances Induced by Coupling between Plasmonic Stub and Circular Cavity Resonators

Abstract: A plasmonic waveguide system composed of metal-insulator-metal (MIM) stub coupled with circular cavity resonator was proposed to produce ultra sharp Fano resonances, which resulted from the coupling between the ultra narrow discrete resonances and the ultra broad spectrum of the plasmonic circular cavity and stub resonator, respectively. The spectral line shapes of the Fano resonances can be easily adjusted by changing the structure parameters. And the transmittance of the system can sharply decrease from peak (“on state”) to valley (“off state”) with wavelength shifts of only about 8 nm. Due to the sharp phase change of the ultra asymmetric Fano resonance, a maximum group index of about 180 can be realized. Also, the ultra sharp spectrum contributes to a highly efficient plasmonic refractive index sensor, which can yield a linear sensitivity of 1277 nm/RIU and figure of merit of about 2.1 × 104. The proposed structure may have potential applications in nanoscale filter, slow light, and refractive index sensor.

Compact frequency reconfigurable filtennas using varactor loaded T-shaped and H-shaped resonators for cognitive radio applications

Abstract: In this study, novel compact filtennas with large tunable frequency band are proposed for cognitive radio (CR) applications. Tunability is achieved by integrating a tunable T-shaped and H-shaped bandpass filter with a planar ultra-wideband monopole antenna. The T-shaped filter consists of a microstrip resonator loaded with a stub. The H-shaped filter is composed of two connected microstrip resonators. The proposed tuning technique for both filters is based on centrally loading the stub and the H-shaped with only a single varactor for miniaturisation. Increasing the varactor capacitance results in decreasing the even resonant mode of the resonator without affecting the dominant odd mode. Measurements results show that the proposed T-shaped and H-shaped filtennas are capable of tuning over a wide operating band of 1.68 and 1.73 GHz covering continuous bands for CR communication with 32.9% frequency tuning range (TR) from 4.26 to 5.94 GHz and with 36.7% frequency TR from 3.85 to 5.58 GHz, respectively. Moreover, the radiation patterns are stable over the operating frequency ranges. The frequency characteristics and radiation performance are successfully optimised using 3D full-wave electromagnetic simulator. The fabricated designs are measured for verification purposes. Good agreements are found between simulated and measured results.

Plasmonic-Induced Transparency and Slow-Light Effect Based on Stub Waveguide with Nanodisk Resonator

Abstract: A compact plasmonic system based on a stub metal-insulator-metal (MIM) waveguide coupled with a nanodisk resonator for plasmonic-induced transparency (PIT) has been proposed and numerically simulated by employing the finite-difference time-domain (FDTD). A reasonable analysis of the transmission features based on the temporal coupled-mode theory is given and is in good agreement with the FDTD simulation. In addition, the relationship between the transmission characteristics and the geometric parameters including the radius of the nanodisk, the coupling distance, and the deviation length between the stub and the nanodisk is studied in a step further. By optimum designing, the transmission of the PIT system can reach to as high as 90 %, as well as the group index can be over 88. The characteristics of our plasmonic system indicate an important potential application in integrated optical circuits such as optical storage, ultrafast plasmonic switch, highly performance filter and slow-light devices.

A Non-Invasive Phase Sensor for Permittivity and Moisture Estimation Based on Anomalous Dispersion

Abstract: The traditional microwave resonance sensors are based on the measurement of the frequency shift and bandwidth of a resonator’s amplitude spectrum. Here we propose a novel sensing scheme in which the material properties are estimated by determining the changes in the phase spectrum of an anomalous-phase resonator. In the proposed phase sensing, we exploit the unique double phase reversal which takes place on the edges of the anomalous dispersion region as a signature to detect the resonance. We show that with the phase sensing, a significant reduction in detection errors compared to the traditional sensing can be obtained because of the noise immunity offered by the phase detection and also due to the strong dispersive phase response that reduces the sensor’s dependence on the external environment. We also show that the bandwidth determination procedure of the resonance which is needed to characterize the sample losses is significantly simplified. The concept of phase sensing is shown by devising an experimental microstrip open stub resonator whose frequency response lies in the anomalous dispersion region. The dielectric characteristics of the samples placed on the stub are extracted from the resonant frequency and the slope of the phase response. We also demonstrate that the changes in moisture levels can also be detected by utilizing the phase sensing method.

Compact dual polarised V slit, stub and slot embedded circular patch antenna for UMTS/WiMAX/WLAN applications

Abstract: A single probe-fed novel V slit, stub and slot embedded circular microstrip antenna with resonances in the three bands of UMTS, worldwide interoperability for microwave access (WiMAX) and WLAN is presented. The polarisation is circular in the UMTS band and linear in the other two bands. Asymmetrical V slits in the patch boundary along with an embedded circular slot in the patch centre are employed to introduce the perturbation necessary for circular polarisation. Impedance bandwidths (BWs) of 4.2, 2 and 6.2%, respectively, in the three bands centred at 2, 3.5 and 5.6 GHz are obtained. The axial ratio BW is 2.3% in the UMTS band. Moderate gains of 4.4, 3.5 and 2.8 dBi are obtained in the three bands. There is a patch size reduction of about 48% when compared with the conventional circular patch antenna at a fixed operating frequency. The radiation pattern is directional in the WiMAX band and nearly omnidirectional in the WLAN band.

Influential and theoretical analysis of nano-defect in the stub resonator.

Abstract: We investigate a classic optical effect based on plasmon induced transparency (PIT) in a metal-insulator-metal (MIM) bus waveguide coupled with a single defective cavity. With the coupled mode theory (CMT), a theoretical model, for the single defective cavity, is established to study spectral features in the plasmonic waveguide. We can achieve a required description for the phenomenon, and the theoretical results also agree well with the finite-difference time-domain (FDTD) method. Our researches show that the defect’s position and size play important roles in the PIT phenomenon. By adjusting the position and size of the defect, we can realize the PIT phenomenon well and get the required slow light effect. The proposed model and findings may provide guidance for fundamental research of the control of light in highly integrated optical circuits.

Compact Microstrip Tri-Band Bandpass Filter Using New Stubs Loaded Stepped-Impedance Resonator

Abstract: This letter presents a novel tri-band bandpass filter (TB-BPF) based on proposed stubs loaded stepped-impedance resonator (SLSIR). The first three resonant modes of proposed SLSIR can be independently controlled by the shorted high-impedance section of SIR, the loaded open stub and the loaded shorted stub, respectively, resulting in the independency of central frequencies and return losses of three passbands. As an example, a TB-BPF operating at 0.9/1.8/2.45 GHz are designed and fabricated. Due to the cancelling effect of mixed electric and magnetic coupling, the virtual grounds existed in SLSIR and the introduced embedded open stub, six transmission zeros are realized around three passbands, resulting in the high passband selectivity and band-to-band isolation. The fabricated TB-BPF also has a compact size of $0.06\lambda_{\mathbf{g}}\times 0.162\lambda_{\mathbf{g}}$ .

Compact CPW UWB diversity slot antenna with dual band‐notched characteristics

Abstract: A compact coplanar waveguide (CPW) fed ultrawideband (UWB) slot antenna for multiple-input-multiple-output (MIMO)/diversity applications is presented in this letter. The antenna consists of two coplanar waveguides (CPWs) feeding circular radiating elements and a protruded stub, which is placed at between them. The circular radiating elements are arrange orthogonally and fed perpendicularly to obtain polarization diversity. Notched band at X-band communication downlinks is achieved by etching split ring resonator slots in the radiators and the other notched band at WLAN system is achieved by the collaboration of arc-shaped strips and the protruded stub. The protruded stub not only can help to achieve band rejection but also can reduce mutual coupling between two ports. As all of the structures are printed in one layer, it can be very easily to be integrated with RF front-end circuits. Simulated and measured results show that the proposed antenna meets the 10-dB impedance bandwidth from 3.4 to 12 GHz and isolation better than 15 dB at most of the band. Good diversity performance in terms of envelope correlation coefficient and the ratio of mean effective gain demonstrates that the antenna is quite suitable for MIMO UWB applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:989–994, 2016

Sensing Application in Fano Resonance With T-Shape Structure

Abstract: A T-shape plasmonic structure, consisting of a stub resonator coupled with bus waveguide and cavity, has been investigated numerically and theoretically. Due to the near-field coupling mechanism between bright and dark modes, plasmon induced transparency can be observed in transmission spectrum. Moreover, it is demonstrated theoretically that the first order resonance mode can exist or not in the cavity by adjusting lateral displacement ( S ), which leads to the appearance or disappearance of the narrow transmission dip together with a steep Fano resonance in reflection spectrum. The effects of different parameters on a figure of merit (FOM) are investigated in detail. In sensing applications, the T-shape structure yields a sensitivity of ∼1090 nm shift per refractive index unit and a FOM of 33340. The results indicate that the width of cavity ( w c) is more sensitive than the distance ( g ) and length ( L ) for FOM. The transparency and Fano resonance effects may have potential applications in optical switch, slow-light devices, and nano sensor in highly integrated optical circuits.

Tunable high quality factor in two multimode plasmonic stubs waveguide.

Abstract: We numerically investigate the optical characteristics of a metal-dielectric-metal (MDM) waveguide side-coupled with two identical multimode stub resonators. Double plasmon-induced transparency (PIT) peaks with narrow full width at half maximum (FWHM) and high quality factor (Q-factor) can be observed in this structure. The Q-factors of PIT peaks in two stub resonators system are larger than those in single stub resonator system. A multimode coupled-radiation oscillator theory (MC-ROT), which is derived from ROT, is proposed to analyze the spectral response in the multimode system for the first time. The analytical results are confirmed by the finite-difference time-domain (FDTD) simulation results. We can also find that the Q-factors of the two PIT peaks have an opposite evolution tendency with the change of the stubs parameters and the maximum can reach to 427. These results may provide some applications for ultrasensitive sensors, switches and efficient filters.