Simulation and analysis of single negative metamaterial sensor based on microring resonator

Metamaterials are artificial multifunctional materials that acquire their material properties from their structure, rather than inheriting them directly from the materials they are composed of, and they may provide novel tools to significantly enhance the sensitivity and resolution of sensors. In this paper, we derive the dispersion relation of a cylindrical dielectric waveguide loaded on a negative permeability metamaterial (NPM) layer, and compute the resonant frequencies and electric field distribution of the corresponding Whispering-Gallery-Modes (WGMs). The theoretical resonant frequency and electric field distribution results are in good agreement with the full wave simulation results. We show that the NPM sensor based on a microring resonator possesses higher sensitivity than the traditional microring sensor since with the evanescent wave amplification and the increase of NPM layer thickness, the sensitivity will be greatly increased. This may open a door for designing sensors with specified sensitivity.

A novel microdisk resonator sensor based on negative permeability metamaterials. The dispersion relationship of the cyllindrical waveguide coated with single negative metamaterials is obtained, and the resonant frequency and Q factor working at whisper-gallery-mode (WGM) is computed using finite element method (FEM), and agreement between theoretical results and simulation results is demonstrated to be good. Results show that the sensitivity of the sensor is significantly enhanced by the negative permeability metamaterials, and the Q factor can be tailored by adjusting the distance between the waveguide and the microdisk.

Sensor utilizing metamaterials have opened up a new field of considerable interest. We extend here the works of our group about metamaterial sensor based on Whispering Gallery Mode (WGM), which is constructed with a microring resonator sensor coated with metamaterial layer. We demonstrate that our sensor possesses higher sensitivity than the traditional sensor since the amplification and penetration of evanescent wave by metamaterials.

Tunable surface waves supported by graphene-covered left-handed material structures

For two homogeneous and isotropic media, the angles of the transmitted and reflected waves follow the Snell’s law, which relate them to the angle of incidence and material properties of each medium. When the angle of incidence is larger than the critical angle (the angle of incidence that makes the transmission angle equals π/2), the transmitted wave will decay exponentially in the direction away from the interface. However, we found that by changing one medium into a double negative metamaterial, the transmitted wave will grow exponentially instead. This research can be used for amplifying evanescent transmitted waves by putting thin metamaterial layer between bilayer elastic media.

Advances in MEMS/NEMS techniques have enabled high-Q whispering-gallery modes in integrated microcavities. Potential applications of optical microcavities include quantum informatics, novel micro/nano sources, dynamic filters, and micro/nanosensors. It is important to understand the intrinsic resonant modes of a cavity. In this report, we will analyze whispering-gallery modes in resonators of planar structure which is common in MEMS devices. The wave equation is solved by using the method of separation of variables with appropriate boundary conditions. Analytical formulations are established. The resonance frequencies as well as the electric field distributions in exemplary resonators are presented for a variety of whispering-gallery modes.

AbsIracf - Two-dimensional backward-wave meta-material based on evanescent parallel-plate waveguide filled with uniaxial magnetic tilling with negative transversal permeability is investigated experimentally. The prototype comprised a two-dimensional array of the double ring resonators sandwiched between two metallic plates and it was operating in 8 GHz frequency hand. The backward-wave propagation was verified by the measurement of negative lateral displacement of the beam impinging the meta-material slab at several different angles of incidence I. INTRODUCTION A material which supports propagation of the backward waves ('left-handed material' or 'backward-wave material') was predicted theoretically in sixties by Veselago (I) and realized experimentally for the first time by Smith at al. (2) in 2000. The rather simple type of one-dimensional backward-wave meta-material based on an evanescent waveguide loaded with the split ring resonators was presented in (3). Such a waveguide was interpreted as one-dimensional material with both negative permeability and negative permittivity (3). In (4,5), it was shown that the propagation below the cut-off frequency actually occurs due to uniaxial anisotropy of negative permeability of the meta-material based on the split ring resonators. The extension of this basic principle to two dimensions, similarly to the idea introduced in (6), is investigated experimentally in this paper. 11. THEORETICAL RESULTS Let us analyze the structure that comprises a slab of anisotropic uniaxial magnetic materials sandwiched within the two infinite parallel PEC plates (Fig.1). If the optical axis of the uniaxial material is perpendicular to the plates (the transversal direction), it is obvious that this structure is essentially isotropic in two dimensions. Thus, the electromagnetic energy will propagate in any direction parallel to the plates (the longitudinal direction) in the exactly the same way (the propagation for two perpendicular longitudinal directions is sketched in Fig. 5). For any particular longitudinal direction, one may think of this structure as a parallel plate waveguide. In the lossles case, the longitudinal propagation factor of such a waveguide is given by the simple set of equations (4,51: Here, k, stands for longitudinal propagation factor, ko is a free space propagation factor, g is relative permittivity and p,, and pi, stand for relative permeability in transversal and longitudinal directions of the waveguide, respectively. The symbol f stands for a frequency of the signal, whereas Lo and L are the cut-off frequency of an empty parallel-plate waveguide and the parallel-plate waveguide filled with a material, respectively. If the transversal permeability is negative &<0 ) and the longitudinal permeability is positive (ppO), one must choose the negative sign in front of the square root in (I) for frequencies below the cut-off. This yields the peculiar phenomenon of the backward-wave propagation. Hence, the structure actually behaves as two-dimensional backward-wave meta-material provided that the vector of the magnetic field is perpendicular to the walls (TE 01 mode). If one stacks more parallel plate waveguides in the transversal direction, it is possible to manufacture the two-dimensional 'backward-wave' material of arbitrary thickness, as proposed in (6). The backward-wave propagation below the cut-off frequency can he simply explained by two-dimensional transmission line equivalent circuit of the structure (Fig.2). The distributed series impedance (212) is associated with the transversal permeability. The distributed shunt admittance associated with the relative permittivity (Y,) and the admittance associated with the longitudinal permeability (Y,) form the tank circuit. In the case of the uniaxial material with positive permeability, the series admittance will he also positive. Below the cut-off, the tank circuit behaves as an inductance and, for any direction parallel to the plates, the whole structure behaves as a transmission line with the distributed series inductance and the distributed parallel inductance (L-L transmission line), This kind of transmission line does not support the propagating waves. If the transversal

Pumping a single-mode, tunable, external-cavity laser to excite the whispering gallery modes (WGM) of micro ring resonators (MRRs), a series of equidistant, wide free spectrum range (FSR) can be observed. Frequency shift of FSR can be used to feedback external changes, making MRR very promising in high-sensitivity sensing. In this paper, a novel displacement sensor composed of a micro ring resonator and a waveguide is presented and a designing route for this sensor is discussed. Based on mathematical analysis and the beam propagation methods (BPM), the major parameters including the geometry of MRR and micro cantilever are investigated in detail. Materials selection and fabrication method under current processing technic are also presented. For the typical structure in this paper, the final Q factor is estimated approximately 103 in theory at the wavelength of 1.5&mu;m.Displacement alteration of cantilever is 0.296x10^-6m - 0.535x10^-5m approximately corresponding 10-8-10-6N force loading. The shift of transmission spectrum is about 3.9nm versus perimeter of MRR changing 1&#956;m.

One of the key mandates of modern optoelectronic research is the development of compact photonic integrated circuits, capable of performing many diverse functions for the generation, manipulation, and detection of light, all on a single chip. A key practical requirement for such circuits is the development of optical devices for the localization and processing of light within extremely small dimensions. In recent years, planar microring and microdisk resonators, in which light is confined by total internal reflection, have emerged as versatile photonic elements for filling this role. The high quality factors and long photon storage times associated with the whispering-gallery modes supported by these microcavities result in several technologically useful characteristics, including narrow-band filter response, and large resonant enhancement of the circulating electric field. These properties have been exploited in numerous passive and active device applications, including optical add/drop multiplexers, all-optical switches, and tunable lasers. This thesis describes the study of several unique ring-based optical microcavity geometries based upon the indium gallium arsenide phosphide/indium phosphide alloy semiconductor material system, undertaken in an effort to explore new optoelectronic architectures for confining and manipulating light. The first portion of this work involves the analysis and demonstration of a new microcavity geometry, in which cylindrical Bragg reflection is used for radial optical confinement, as an alternative to total internal reflection. In this class of structures, collectively known as annular Bragg resonators, light can be guided within a ring or pillar defect layer surrounded by cylindrical Bragg mirrors. Several microcavities based upon this configuration are designed and fabricated using a thin InGaAsP quantum well membrane. Using pulsed optical excitation, the characteristics of these structures as low threshold vertically emitting lasers is explored. Second, a total internal reflection-based coupled waveguide-resonator geometry, having applications to low power optical switching and modulation, is analyzed. This geometry makes use of the hybrid integration of a Mach-Zehnder interferometer with a racetrack resonator. Switching takes place using the Mach-Zehnder to control the coupling parameters in the vicinity of the critical coupling condition. Characterization of the static and dynamic output response of a thermooptically actuated InGaAsP-InP hybrid switch device demonstrates good ON-OFF switching contrast, microsecond response time, and reduced switching power in comparison with a conventional Mach-Zehnder configuration. Finally, this work concludes by examining both the annular Bragg resonator and hybrid switch geometries in application to chemical and biological sensing. Both microcavity devices are shown to possess unique characteristics making them ideal for sensitive monitoring of small changes in the refractive index of a chemical or biological analyte.

Optical micro-ring resonator sensors are an emerging category of label-free optical sensors for bio/chemical sensing that have recently been under intensive investigation. Researchers of this technology have been motivated by a tremendous breadth of different applications, including medical diagnosis, environmental monitoring, homeland security, and food quality control, which require sensitive analytical tools. Ring resonator sensors use total internal reflection to support circulating optical resonances called whispering gallery modes (WGMs). The WGMs have an evanescent field of several hundred nanometers into the surrounding medium, and can therefore detect the refractive index change induced when the analyte binds to the resonator surface. Despite the small physical size of a resonator, the circulating nature of the WGM creates extremely long effective lengths, greatly increasing light–matter interaction and improving its sensing performance. Moreover, only small sample volume is needed for detection because the sensors can be fabricated in sizes well below 100 μm. The small footprint allows integration of those ring resonator sensors onto lab-on-a-chip types of devices for multiplexed detection. This chapter gives an introduction to the ring resonator sensing principles. Different ring resonator configurations are illustrated as well, including microspheres, microfabricated planar ring resonators, and capillary-based opto-fluidic ring resonators. Their sensing performances are evaluated and compared quantitatively. Finally, the future development for ring resonator sensors is discussed.

The theory of turning soft x-ray SXR radiation beams by means of concave surfaces through multiple reflections (the “whispering-gallery” effect) is developed. It is demonstrated that concave mirrors are capable of turning an SXR beam by an arbitrary angle determined by their aperture angle. The reflectivities are of the same order of magnitude as those of multilayer mirrors (20–80% at a turn by 90°). The turning mirrors feature a wide spectral transmission band (Δλ ∼ λ). The potentialities of concave mirrors and hollow cylindrical waveguides with respect to concentration and collimation of SXR radiation are considered. The requirements imposed on the smoothness of the reflecting surfaces are obtained and the optimal (as to their optical properties) materials are chosen for their fabrication. The theoretical results are compared to experimental data.

This article presents work on a Silicon-On-Insulator (SOI) compact sensing platform based on Micro Ring Resonators (MRRs). In order to enable correction for variations in environmental conditions (temperature, mechanical stress etc), a study has been performed on the performance of uncoated sensing MRRs, and of SU8- and SiO2-covered reference MRRs. Excellent shielding for both cover materials has been obtained, however, water permeation into the SU8 causes a slow drift in sensor response. We believe that a user-friendly, low-cost and robust way for optical interfacing to MRR sensor chips is required for practical application in Point-Of-Care diagnostics, and that the cost and complexity of optical-electrical read-out systems must decrease. We have taken first steps to realize that vision, by building a prototype free-space optical coupling set-up, which enables non-photonic experts to characterize surface activation processes using MRRs. Moreover, we present our first steps towards on-chip read-out systems. © 2014 SPIE.

The quality factor and the resonant frequency of a resonant cavity are the key factors that need to be considered in the process of resonator design. The wall of cavity is composed of conductor materials which are effective tools to generate high-frequency oscillation. The microwave cavity is widely used. From the perspective of the circuit, it has almost all the properties of LC resonance unit, such as mode selection. Therefore, it is widely used in filters, matching circuits, and antenna design. In industrial applications, the demand for high-frequency resonant cavity is relatively large. A traditional method can increase the resonant frequency of the resonant cavity by reducing the size of the cavity or using the high-order modes. However, as both approaches have their limitations, the design results are not ideal. By combining theoretical calculation and simulation, the factors that affect the resonant frequency of the resonator are analyzed. The results show the relationship between material properties of the filling medium and the resonant frequency of the cavity. Theoretical calculations show that when the left-handed materials are used as filling materials in the cavity, the resonant frequency can be increased without changing the size of the cavity. The results of high frequency structure simulator also prove the above result. Therefore, the resonant frequency of the resonator cannot be limited by the cavity size. It can be seen from the data that compared with reducing the size of the resonator or using high-order modes, filling left-handed materials can improve resonant frequency to a greater extent. The obtained conclusion shows a further progress compared with the traditional theory and provides a theoretical basis for the exploration and design of novel resonators.

Whispering gallery mode (WGM) resonators have been extensively studied in optical range, however, they still have great research potential in terahertz (THz) domain. In this paper, the electric-field distribution of ~0.46 THz in high resistivity float zone silicon (HRFZ-Si) microring resonator was analyzed. By simulating the instantaneous heat dissipation process, thermal relaxation time was obtained which characterizes how fast the heat transfer from mode volume to the substrate. Furthermore, the optothermal dynamics within the resonator was depicted by an ordinary differential equation where both the linear absorption and the nonlinear Kerr effect were accounted. A series of transmission spectra under various input power were simulated. The results showed that unlike the case of optical regime, THz WGM exhibits obvious broadening under high injection power (over 80 mW) due to the relatively high absorption. The study will promote the understanding of interaction between THz wave and matter.

Characteristics optimization in single and dual coupled silicon-on-insulator ring (disk) photonic biosensors