A Microring Resonator Based Negative Permeability Metamaterial Sensor

A novel microring resonator sensor coated with a single negative metamaterial (SNM) layer is proposed. The dispersion relation of hollow cylindrical dielectric waveguide covered with a SNM layer is derived, and resonant frequencies of the corresponding whispering gallery mode are computed. We find that there is a good agreement between the theoretical results and numerical results of resonant frequencies and electric field distributions. Compared with traditional resonator sensor, the sensitivity and resolution are significantly enhanced by SNM, and the Q factor can be tailored by adjusting the distance between the waveguide and the microring.

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.

We investigate the electromagnetic wave propagating in one dimensional photonic crystals with alternating layers of negative permittivity materials and negative permeability metamaterials. The band structure and transmission spectra are obtained. In the negative effective permittivity and negative effective permeability regime, we find new interface modes propagating along the interfaces between the two different media with even and odd parities, respectively. For the oblique incident case, the new propagation modes result in the emergence of a transmission band within the zero-ϕeff gap of these photonic crystals. By adjusting the plasma density or the thickness of the plasma layer, the zero-ϕeff gap as well as the transmission band of the interface modes can be tuned, which can facilitate the design of tunable filters at the microwave frequency range.

In this paper, a systematic approach is presented for finding the resonant frequency, damping factor and EM field distribution of a layered planar structure consisting of chiral media and having arbitrary conductor sheets at the interfaces. The analysis is based on the spectral dyadic Green's function followed by a Ritz-Galerkin's process, using matrix analysis in the Fourier transform spectral domain. The great value of our formulation lies in that it provides methodology for the solutions to chiral layered media problems.

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 1.5μm.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 1μm.

A simulation model for estimation of the optical properties of spherical and spheroid nano plasmonic geometry coupled with organic media has been studied using discrete dipole approximation (DDA) technique. Silver (Ag) and aluminium (Al) metal nano particles (NPs) are used as a plasmonic element surrounded by organic photovoltaic environment [poly (3-hexyl thiophene)] P3HT-(phenyl-C61-buryricacid methyl ester) PCBM blend. The analysis done in the current article depicts considerable influence of shape, aspect ratio and size on the plasmon resonance that facilitates improvement in the performance of nano plasmonic organic system in the useful spectral domain (250–750 nm). Discretisation of dipoles have been done in the DDA and compared with Mie theory to maintain the accuracy of DDA technique. It has been established that the oblate shape Ag and Al NPs with size of 80 nm (both) with aspect ratio 0.35 and 0.20 are the optimized parameter to enhance the optical properties in an organic surrounding. The optical properties are studied in terms of wavelength dependent extinction spectrum and resonant electric field distribution. Broadband electromagnetic field coupling under the plasmonic effect has led to considerable improvement in the photon absorption inside the organic environment that has been supported by the enhanced J–V curve for different nano geometries. Results of the present article can be used as a guiding principle for the plasmonic light trapping devices to improve their optical properties and electrical properties.

A refractive index (RI) sensor based on straight silicon strip waveguide and a hybrid plasmonic microring resonator is presented. The hybrid waveguide is made up of a Metal-Air-Silicon structure, where the electric field is significantly enhanced in the narrow air gap. The transmission spectrum and electric field distribution of this sensor structure are simulated using Finite Element Method (FEM). Due to a large overlap of the optical field in the hybrid microring resonator and the sensing medium, this sensor can be used for both gas and bio sensing applications. The best sensitivity of 690 nm/RIU and 401 nm/RIU is obtained for gas and bio sensing, respectively. The obtained values are relatively high as compared to conventional dielectric microring resonator sensors. Our proposed sensor design has a potential to find further applications in biomedical science and nanophotonic circuits.

We report the design and characterization of biosensors based on one-dimensional photonic-crystal reflectance filters operating at near-ultraviolet wavelengths. Rigorous coupled-wave analysis simulations predict an increased confinement of the resonant electric field at the surface of this biosensor as compared to previously fabricated near-infrared photonic-crystal biosensors. This change in the resonant electric field provides an improvement of over 4.5 times in the surface-sensitivity to bulk-sensitivity ratio, and therefore enables enhanced detection resolution for biomolecules adsorbed on the biosensor surface. These biosensors will be especially important for applications requiring the detection of small molecules or ultralow analyte concentrations.

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.

Electric field distribution in porous piezoelectric materials during polarization

The enhancement of a liquid‐based fluorescence assay is demonstrated, using the resonant electric fields from a photonic crystal (PC) surface. Using a molecular beacon nucleic acid fluorescence resonant energy transfer (FRET) probe for a specific miRNA sequence, an 8x enhancement of the fluorescence emission signal is shown. The approach may be utilized for any liquid‐based fluorescence assay for applications in point‐of‐care diagnostics, environmental monitoring, or pathogen detection.(Picture: Y. Tan, E. Sutanto, A. G. Alleyne, and B. T. Cunningham, pp. 266–275, in this issue)

We investigate spatial fluctuations of the cooperative emission of radiation by a two-level-atom system driven by a resonant electric field. For very small absorption length, a directional photon antibunching effect is expected.

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.

Over the last fifteen years, a series of theoretical and experimental investigations have demonstrated the usefulness of circular geometries to tailor second‐order nonlinear optical effects. However, until recently, such effects have remained rather weak, calling for their enhancement. In parallel, developments in the field of high quality factor spherical or ring resonators have shown that many different types of light‐matter interactions can be dramatically amplified when light is coupled in the whispering gallery modes of such resonators. In high‐quality spherical micro‐resonators, close to one million interactions can occur between a nonlinear molecule and a circulating light pulse. Recent research on nonlinear optics in spherical geometry is reviewed, from micrometer‐size spheres to whispering gallery mode resonators.