Vertical Resonator Research Articles

Plasmon coupling in vertical split-ring resonator metamolecules.

The past decade has seen a number of interesting designs proposed and implemented to generate artificial magnetism at optical frequencies using plasmonic metamaterials, but owing to the planar configurations of typically fabricated metamolecules that make up the metamaterials, the magnetic response is mainly driven by the electric field of the incident electromagnetic wave. We recently fabricated vertical split-ring resonators (VSRRs) which behave as magnetic metamolecules sensitive to both incident electric and magnetic fields with stronger induced magnetic dipole moment upon excitation in comparison to planar SRRs. The fabrication technique enabled us to study the plasmon coupling between VSRRs that stand up side by side where the coupling strength can be precisely controlled by varying the gap in between. The resulting wide tuning range of these resonance modes offers the possibility of developing frequency selective functional devices such as sensors and filters based on plasmon coupling with high sensitivity.

A single eye 3D image perception device using vertical double ring resonator construction

ABSTRACTA single eye three‐dimensional (3D) imaging perception using a single 3D imaging pixel is designed and manipulated, which is the interesting device configuration that can be used for various applications. The device configuration is consisted of double conjugate mirrors that can be vertically fabricated, which can be used to form the 3D image using a single pixel configuration, from which the large area device construction is also possible. By adjusting the microconjugate mirror parameters, then the matching between both microconjugate mirrors can lead to obtain the required 3D images. Results obtained have shown that the 3D image outputs can be achieved and used for 3D pixel imaging. The 3D image output can be confirmed by the four‐wave mixing output balancing profile, which is achieved. In applications, the large area 3D images can be constructed using the large area 3D imaging device, from which the large area can be coverage by the microconjugate mirror array, which can be useful for various applications. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1802–1805, 2015

Collocated Z-Axis Control of a High-Speed Nanopositioner for Video-Rate Atomic Force Microscopy

A key hurdle to achieve video-rate atomic force microscopy (AFM) in constant-force contact mode is the inadequate bandwidth of the vertical feedback control loop. This paper describes techniques used to increase the vertical tracking bandwidth of a nanopositioner to a level that is sufficient for video-rate AFM. These techniques involve the combination of: a high-speed XYZ nanopositioner; a passive damping technique that cancels the inertial forces of the Z actuator which in turns eliminates the low 20-kHz vertical resonant mode of the nanopositioner; an active control technique that is used to augment damping to high vertical resonant modes at 60 kHz and above. The implementation of these techniques allows a tenfold increase in the vertical tracking bandwidth, from 2.3 (without damping) to 28.1 kHz. This allows high-quality, video-rate AFM images to be captured at 10 frames/s without noticeable artifacts associated with vibrations and insufficient vertical tracking bandwidth.

Spectra of mechanical cavity modes in distributed Bragg reflector based vertical GaAs resonators

Distributed Bragg reflector based semiconductor resonators constitute paradigmatic systems where cavity optomechanical and optoelectronic phenomena can be simultaneously active in the same device. High GHz range mechanical frequencies and ultrastrong optomechanical couplings are additional attractive features for applications. We report here a detailed spectroscopic study of the fundamental optomechanical resonances of such a device. The existent challenge to study vibrational frequencies that are above the bandwidth of current electronics is solved using a purposely made tandem Fabry-Perot-triple spectrometer. A full theoretical description of the Raman process including electronic, vibrational, and optical confinement is presented to describe the experiments. These results open the path for the demonstration of polariton optomechanical phenomena in these devices.

Vertical split-ring resonator based nanoplasmonic sensor

Split-ring resonators (SRRs) have been the subject of investigation as plasmonic sensors that operate by sensing plasmon resonance shift δλ when exposed to a medium with a refractive index change δn. However, conventional planar SRRs have their plasmon fields spread into the substrates, reducing accessible sensing volume and its sensing performance. Such a limitation can be eradicated with vertical SRRs in which the plasmon fields localized in SRR gaps are lifted off from the substrate, allowing for greatly enhanced sensitivity. Here, we demonstrate the highest sensitivity among reported SRR-based sensors in optical frequencies.

Production of vertical nanowire resonators by cryogenic-ICP–DRIE

Silicon resonant sensors with large surface area-to-volume ratios provide high weighing sensitivity. This fact implies the possibility for detection of slight mass changes [i.e. by attached nanoparticles (NPs)]. Vertical silicon nanowire (SiNW) resonators are therefore suitable for exposure assessment or airborne NPs. SiNW arrays are top-down fabricated by nanolithography and subsequent inductively coupled plasma reactive ion etching at cryogenic temperature. Nanolithography is performed by conventional UV-lithography and nanoimprint for even smaller structures. Wire diameters are further reduced by multiple thermal oxidations and oxide stripping at times. Parameter effects of cryogenic dry etching are studied for SiNW arrays.

Analysis of characteristics of vertical coupling microring resonator

By using the coupled mode theory and the transfer matrix technique, the optical transfer function is presented for analyzing the size of the waveguide, radius of the microring, free spectral range and amplitude coupling ratio of the vertical coupling microring resonator. Under the central wavelength of 1550 nm, optimization and simulation are performed when the central deviation between the ring and the channel is 0,0.5, 1 μm, respectively, the 3-dB bandwidth of the spectral response is about 0.21, 0.09, 0.03 nm, and the intensity of the nonresonant light is below −30, −40, −50 dB, respectively.

Sharp whispering-gallery modes in rolled-up vertical SiO_2 microcavities with quality factors exceeding 5000

Record high quality (Q) factors of 5400 in vertical microtube ring resonators operated in emission mode are demonstrated. This is achieved by rolling-up a differentially strained SiO2 layer. We also present a theoretical model to investigate the limit of the Q factor. This model especially includes the effect of interlayer voids in the rolled-up geometry, which is found to have a larger effect than scattering due to notches in the spiral shape.

Manufacturing Error in the Application of Improving Spectrum for a Vertical Coupling Microring Resonator

All the effects of manufacturing errors on transmission spectrum are analyzed for a vertical coupling microring resonator (MRR). Results show that the core refractive index, core thickness and radius errors of ring result in central wavelength shift of the transmission spectrum, and the central deviation and thickness between the ring and channel lead to nonresonant light intensity change. In order to obtain satisfactory spectrum for a fabricated MRR device, some allowed manufacturing errors are discussed, and the accumulation and compensation of manufacturing errors are investigated.

Polarization properties of solid-state organic lasers

The polarization states of lasers are crucial issues both for practical applications and fundamental research. In general, they depend in a combined manner on the properties of the gain material and on the structure of the electromagnetic modes. In this paper, we address this issue in the case of solid-state organic lasers, a technology which enables one to vary independently gain and mode properties. Different kinds of resonators are investigated: in-plane microresonators with Fabry-Perot, square, pentagon, stadium, disk, and kite shapes, and external vertical resonators. The degree of polarization $P$ is measured in each case. It is shown that although transverse electric modes prevail generally ($P$ > 0), the kite-shaped microlaser generates negative values for $P$ (i.e., a flip of the dominant polarization which becomes mostly transverse magnetic polarized). In general, we demonstrate that both the pump polarization and the resonator geometry can be used to tailor the polarization of organic lasers. With this aim in view, we, at last, investigate two other degrees of freedom, namely upon using resonant energy transfer and upon pumping the laser dye to a higher excited state. We then demonstrate that significantly lower $P$ factors can be obtained.

Effects of manufacturing errors on the characteristics of a polymer vertical coupling microring resonator

The effects of manufacturing errors on transmission characteristics are analyzed for a polymer vertical coupling microring resonator. Calculated results show that the errors cause a shift and shape change of the transmission spectrum compared to the designed case without errors. Furthermore, accumulation and compensation for the errors is researched. In order to realize the normal filtering for the fabricated microring resonator device, some allowed errors are discussed.

Vertical input optical ring resonator with differential operation for optical sensor

A novel waveguide ring resonator optical sensor with two resonant wavelength channels is proposed for a refractive index measurement of a test sample placed on the sensor substrate and its performance characteristics are investigated analytically and numerically. The waveguide device consists of a ring resonator, a split-ring-shaped loop waveguide, and a vertical input/output grating coupler, in which the loop waveguide acts as an additional resonator and provides another output wavelength channel of the sensor. The differential detection between the two wavelength channels enables the highly sensitive detection with temperature compensation. A numerical simulation based on a finite difference time domain (FDTD) method shows that a precise index change detection with a resolution of 10−6 can be achieved using of the proposed device.

Dynamic response analysis of single-span guideway caused by high speed maglev train

High speed maglev is one of the most important reformations in the ground transportation systems because of its no physical contact nature. This paper intends to study the dynamic response of the single-span guideway induced by moving maglev train. The dynamic model of the maglev train-guideway system is established. In this model, a maglev train consists of three vehicles and each vehicle is regarded as a multibody system with 34 degrees-of-freedom. The guideway is modeled as a simply supported beam. Considering the motion-dependent nature of electromagnetic forces in the maglev system, an iterative approach is presented to compute the dynamic response of a maglev train-guideway system. The histories of the train traversing the guideways are simulated and the dynamic responses of the guideway and the train vehicles are calculated. A field experiment is carried out to verify the results of the analysis. The resonant conditions of single-span guideway are analyzed. The results show that all the dynamic indexes of train-guideway system are far less than permissive values of railway and maglev system, the vertical resonant of guideways caused by periodical excitations of the train will not happen.

Plasmonic filter with sub-waveguide coupled to vertical rectangular resonator structure

We present and analyze novel vertical rectangular resonator filter based on metal–insulator–metal (MIM) structure. Finite difference time domain (FDTD) method is used in numerical analysis in this paper. Calculations and simulations reveal that the vertical rectangular resonator behaves as plasmonic filter. The free spectral range (FSR) for vertical rectangular resonator is twice as wide as that for transverse rectangular resonator. The aperture-coupled vertical rectangular resonator is also studied in detail. Investigation shows that the transmission curve contains narrow and high peaks, which can be up to 92%.

垂直耦合结构纳米微环谐振器工艺失准分析

垂直耦合结构纳米微环谐振器工艺失准分析

Vertical Growth and Resonator Properties of Hexagonally Shaped Zinc Oxide Nanonails

We synthesized vertically aligned nail-shaped ZnO nanocrystal arrays on silicon substrates via a combination of a carbothermal reduction method and textured ZnO seeding layers that were precoated on silicon substrates by thermally decomposing zinc acetate, and studied their optical properties using cathodoluminescence (CL) and photoluminescence techniques. The ZnO nanonails show a sharp band-gap edge UV emission and a defect-related broad green emission. Monochromatic CL images of an individual ZnO nanonail show variations in spatial distributions of respective CL bands that had different origins. We attribute the spatial variation of CL images to an uneven distribution of luminescent defects and/or a structure-related light out-coupling from hexagonal ZnO nanostructures. The most distinct CL feature from the hexagonal head of an individual ZnO nanonail was the occurrence of a series of distinct resonant peaks within the visible wavelength range. It appeared that the head of a nanonail played the role of a hexagonal cavity so that polarization-dependent whispering gallery modes were stimulated by electron beam excitation.

Fast light generation through velocity manipulation in two vertically-stacked ring resonators

Speed manipulation of optical pulses is a very attractive research challenge enabling next-generation high-capacity all-optical communication networks. Pulses can be effectively slowed by using different integrated optical structures such as coupled-resonator waveguiding structures or photonic crystal cavities. Fast light generation by means of integrated photonic devices is currently a quite unexplored research field in spite of its crucial importance for all-optical pulse processing. In this paper, we report on the first theoretical demonstration of fast light generation in an ultra-compact double vertical stacked ring resonator coupled to a bus waveguide. Periodic coupling between the two rings leads to splitting and recombining of symmetric and anti-symmetric resonant modes. Re-established degenerate modes can form when a symmetric and an anti-symmetric mode having different resonance order exhibit the same resonance wavelength. Under degenerate mode conditions, wide wavelength ranges where the group velocity is negative or larger than the speed of light in vacuum are generated. The paper proves how this physical effect can be exploited to design fast light resonant devices. Moreover, conditions are also derived to obtain slow light operation regime.

Vertical MEMS Resonators for Real-Time Clock Applications

MEMS resonators are today widely investigated as a desirable alternative to quartz resonators in real-time clock applications, because of their low-cost, integration capability properties. Nevertheless, MEMS resonators performances are still not competitive, especially in terms of frequency stability and device equivalent resistance (and, then, power consumption). We propose a new structure for a MEMS resonator, with a vertical-like transduction mechanism, which exhibits promising features. The vertical resonator can be fabricated with the low-cost, high performance THELMA technology, and it is designed to be efficiently frequency tunable. With respect to the commonly investigated lateral resonators, it is expected to have lower equivalent resistances and improved large-scale repeatability characteristics.

Design and Analysis of Vertical Split Ring Resonator and Its Application to Unbalanced–Balanced Filter

We present a design method and analysis for a vertical split ring resonator (SRR). Furthermore, we propose an unbalanced-balanced filter using vertical SRRs. First, we explain vertical SRR with a stepped impedance resonator (SIR) using virtual ground. The resonance frequency is theoretically derived based on asymmetric coupled transmission lines. The resonance frequencies of vertical SRRs, calculated by our derived equation, are in good agreement with those of 3-D simulations and measurements. Next, this resonator is applied to an unbalanced-balanced filter based on low-temperature co-fired ceramic (LTCC). The attenuation poles of this filter are controlled by coupling between high-impedance lines similar to a two-pole filter with a SIR. The dimensions of the measured filter implemented with LTCC are 2.0 × 1.2 × 0.60 mm. The insertion loss is 2.80 dB in a 2.4-GHz band. Good agreement between measured and computed results is obtained.

Influence Prediction of Tissue Injury on Frequency Variations of the Lumbar Spine under Vibration

A three-dimensional finite element model of the spine T12-S1 segment was developed and used to investigate biodynamics characteristics of the human lumbar spine. The T12-S1 model was carefully built including spinal vertebrae, intervertebral discs, and ligaments so as to approach the real human spine. Finite element modal analysis was carried out to obtain vibration modes and resonant frequencies of the spine. The analytical results indicate that the vertical resonant frequency of the spinal T12-S1 segment with a mass of 40 kg on the top vertebra is 7.68 Hz. The vertical resonant frequencies of spine motion segments decrease with the number of spine motion segments increasing. The tissue injury, such as disc denucleation and removal both of facet articulations and their capsular ligaments may decrease the resonant frequencies of spine in different extent. The denucleation makes larger influence on vertical resonant frequencies than facetectomy does. The denucleation is more harmful to the facet articulations under whole body vibration. The dynamic characteristics of the T12-S1 model accords with the actual human spine, and it is useful for the relative studies of the human spine, such as biomechanical characteristics, vibration-related injury mechanism of the human spine, and development of vibration-related mechanical products.