scholarly journals Coupling and Optical Analysis of a Round-Cornered Square-Shaped Microresonator

2021 ◽  
Vol 11 (18) ◽  
pp. 8659
Author(s):  
Prabodh Panindre ◽  
N.S.Susan Mousavi ◽  
Bruna Paredes ◽  
Mahmoud Rasras ◽  
Sunil Kumar
Keyword(s):  
Quality Factor ◽  
Spectral Response ◽  
Extinction Ratio ◽  
Optical Filter ◽  
Silicon On Insulator ◽  
Finite Domain ◽  
Radius Of Curvature ◽  
Quality Factors ◽  
Curvature Effects ◽  
Coupling Parameters

An on-chip structure consisting of a round-cornered square-shaped (RCSS) resonator as an optical filter is studied via optical experiments, analytical modeling, and numerical techniques. A general coupling model is shown to accurately represent the entire spectral response; the model also provides an understanding of the influence of geometrical and coupling parameters on the resonance characteristics of the RCSS microresonators. The selection of an optimum radius of curvature for rounding off the sharp corners of square microresonators can provide higher quality factors than that of conventional circular resonators. The rotation of the RCSS at the central corner coupling point is also shown to improve the quality factor and remove the minimal phase mismatch requirement and dependency on interaction length. The model results are validated with an electromagnetic finite domain analysis (EMFD) and optical experiments, for which an RCSS on a silicon-on-insulator platform is fabricated. It is shown that the optical performance characteristics (quality factor, transmission ratio, and extinction ratio) of the microresonators are very sensitive to the coupling parameters and must be carefully considered in addition to geometrical length, rotation, and curvature effects. Due to the change in coupling introduced by rotation, the quality factor of the round-cornered square-shaped microresonator can be significantly larger than a circular ring with the same size, thereby establishing RCSS as a competitive alternative to circular microresonators.

scholarly journals Optimization of tunable guided-mode resonance filter based on refractive index modulation of graphene

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hwa-Seub Lee ◽  
Joon Young Kwak ◽  
Tae-Yeon Seong ◽  
Gyu Weon Hwang ◽  
Won Mok Kim ◽  
...  
Keyword(s):  
Near Infrared ◽  
Spectral Response ◽  
Extinction Ratio ◽  
Optical Filter ◽  
Optical Signal ◽  
Design Guidelines ◽  
Refractive Index Modulation ◽  
Guided Mode ◽  
Index Contrast ◽  
Guided Mode Resonance

AbstractTo fabricate a tunable optical filter with a fast response in the near infrared region, a tunable guided-mode resonance (GMR) filter using graphene was proposed and its performance was optimized. In this study, a rigorous coupled wave analysis method was employed to systematically investigate the effects of geometrical configuration of graphene-integrated GMR filters and the optical properties of constituent materials including graphene on their spectral response in terms of tunability and extinction ratio. It was found that as the graphene is located close to the waveguide and the evanescent-field strength at the interface increases, the GMR filter exhibits better tunability. The bandwidth of the filter could be drastically reduced by adopting a low-index contrast grating layer, so that the extinction ratio of an optical signal could be greatly improved from 0.91 dB to 27.99 dB as the index contrast decreased from 0.99 to 0.47, respectively. Furthermore, new practical device designs, that is easy to fabricate and effectively implement the electric-field doping of graphene at low gate voltage, were also suggested and theoretically validated. These results demonstrate not only the excellent potential of a graphene-based tunable GMR filter but also provide practical design guidelines for optimizing the device performance.

scholarly journals A Resonant Pressure Microsensor with a Wide Pressure Measurement Range

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 382
Author(s):  
Chao Xiang ◽  
Yulan Lu ◽  
Chao Cheng ◽  
Junbo Wang ◽  
Deyong Chen ◽  
...  
Keyword(s):  
Chemical Mechanical Planarization ◽  
Measurement Range ◽  
Silicon On Insulator ◽  
Anodic Bonding ◽  
Pressure Measurements ◽  
Quality Factors ◽  
Deep Reactive Ion Etching ◽  
Wide Range ◽  
Form Pressure ◽  
Silicon Islands

This paper presents a resonant pressure microsensor with a wide range of pressure measurements. The developed microsensor is mainly composed of a silicon-on-insulator (SOI) wafer to form pressure-sensing elements, and a silicon-on-glass (SOG) cap to form vacuum encapsulation. To realize a wide range of pressure measurements, silicon islands were deployed on the device layer of the SOI wafer to enhance equivalent stiffness and structural stability of the pressure-sensitive diaphragm. Moreover, a cylindrical vacuum cavity was deployed on the SOG cap with the purpose to decrease the stresses generated during the silicon-to-glass contact during pressure measurements. The fabrication processes mainly contained photolithography, deep reactive ion etching (DRIE), chemical mechanical planarization (CMP) and anodic bonding. According to the characterization experiments, the quality factors of the resonators were higher than 15,000 with pressure sensitivities of 0.51 Hz/kPa (resonator I), −1.75 Hz/kPa (resonator II) and temperature coefficients of frequency of 1.92 Hz/°C (resonator I), 1.98 Hz/°C (resonator II). Following temperature compensation, the fitting error of the microsensor was within the range of 0.006% FS and the measurement accuracy was as high as 0.017% FS in the pressure range of 200 ~ 7000 kPa and the temperature range of −40 °C to 80 °C.

scholarly journals Temperature Characteristics of a Contour Mode MEMS AlN Piezoelectric Ring Resonator on SOI Substrate

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 143
Author(s):  
Sitao Fei ◽  
Hao Ren
Keyword(s):  
Quality Factor ◽  
Bottom Electrode ◽  
Temperature Stability ◽  
Cryogenic Cooling ◽  
Silicon On Insulator ◽  
Temperature Hysteresis ◽  
Sensing Applications ◽  
Doped Silicon ◽  
Heavily Doped ◽  
Contour Mode

As a result of their IC compatibility, high acoustic velocity, and high thermal conductivity, aluminum nitride (AlN) resonators have been studied extensively over the past two decades, and widely implemented for radio frequency (RF) and sensing applications. However, the temperature coefficient of frequency (TCF) of AlN is −25 ppm/°C, which is high and limits its RF and sensing application. In contrast, the TCF of heavily doped silicon is significantly lower than the TCF of AlN. As a result, this study uses an AlN contour mode ring type resonator with heavily doped silicon as its bottom electrode in order to reduce the TCF of an AlN resonator. A simple microfabrication process based on Silicon-on-Insulator (SOI) is presented. A thickness ratio of 20:1 was chosen for the silicon bottom electrode to the AlN layer in order to make the TCF of the resonator mainly dependent upon heavily doped silicon. A cryogenic cooling test down to 77 K and heating test up to 400 K showed that the resonant frequency of the AlN resonator changed linearly with temperature change; the TCF was shown to be −9.1 ppm/°C. The temperature hysteresis characteristic of the resonator was also measured, and the AlN resonator showed excellent temperature stability. The quality factor versus temperature characteristic was also studied between 77 K and 400 K. It was found that lower temperature resulted in a higher quality factor, and the quality factor increased by 56.43%, from 1291.4 at 300 K to 2020.2 at 77 K.

scholarly journals Optimal Design of an Ultrasmall SOI-Based 1 × 8 Flat-Top AWG by Using an MMI

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Hongqiang Li ◽  
Yaoting Bai ◽  
Xiaye Dong ◽  
Enbang Li ◽  
Yang Li ◽  
...  
Keyword(s):  
Insertion Loss ◽  
Spectral Response ◽  
Beam Propagation Method ◽  
Silicon On Insulator ◽  
Optimized Design ◽  
Arrayed Waveguide Grating ◽  
Channel Spacing ◽  
Waveguide Grating ◽  
Passband Width ◽  
Arrayed Waveguide

Four methods based on a multimode interference (MMI) structure are optimally designed to flatten the spectral response of silicon-on-insulator- (SOI-) based arrayed-waveguide grating (AWG) applied in a demodulation integration microsystem. In the design for each method, SOI is selected as the material, the beam propagation method is used, and the performances (including the 3 dB passband width, the crosstalk, and the insertion loss) of the flat-top AWG are studied. Moreover, the output spectrum responses of AWGs with or without a flattened structure are compared. The results show that low insertion loss, crosstalk, and a flat and efficient spectral response are simultaneously achieved for each kind of structure. By comparing the four designs, the design that combines a tapered MMI with tapered input/output waveguides, which has not been previously reported, was shown to yield better results than others. The optimized design reduced crosstalk to approximately −21.9 dB and had an insertion loss of −4.36 dB and a 3 dB passband width, that is, approximately 65% of the channel spacing.

Stiffness Constants for Composite Beams Including Large Initial Twist and Curvature Effects

1995 ◽  
Vol 48 (11S) ◽  
pp. S61-S67 ◽  
Author(s):  
Carlos E. S. Cesnik ◽  
Dewey H. Hodges
Keyword(s):  
Wave Length ◽  
Three Dimensional ◽  
Radius Of Curvature ◽  
Cross Sectional ◽  
Curvature Effects ◽  
Three Dimensional Representation ◽  
Stiffness Model ◽  
Sectional Analysis ◽  
Three Dimensional Elasticity ◽  
Coupling Phenomena

An asymptotically exact methodology, based on geometrically nonlinear, three-dimensional elasticity, is presented for cross-sectional analysis of initially curved and twisted, nonhomogeneous, anisotropic beams. Through accounting for all possible deformation in the three-dimensional representation, the analysis correctly accounts for the complex elastic coupling phenomena in anisotropic beams associated with shear deformation. The analysis is subject only to the restrictions that the strain is small relative to unity and that the maximum dimension of the cross section is small relative to the wave length of the deformation and to the minimum radius of curvature and/or twist. The resulting cross-sectional elastic constants exhibit second-order dependence on the initial curvature and twist. As is well known, the associated geometrically-exact, one-dimensional equilibrium and kinematical equations also depend on initial twist and curvature. The corrections to the stiffness model derived herein are also necessary in general for proper representation of initially curved and twisted beams.

Application of bandlimited anelastic models to wave propagation in highly attenuative media

1995 ◽  
Vol 85 (5) ◽  
pp. 1359-1372
Author(s):  
Hsi-Ping Liu
Keyword(s):  
Wave Propagation ◽  
Quality Factor ◽  
Lower Limit ◽  
Relaxation Function ◽  
Function Approach ◽  
Creep Function ◽  
Frequency Range ◽  
Quality Factors ◽  
Low Frequencies ◽  
Near Surface

Abstract Because of its simple form, a bandlimited, four-parameter anelastic model that yields nearly constant midband Q for low-loss materials is often used for calculating synthetic seismograms. The four parameters used in the literature to characterize anelastic behavior are τ1, τ2, Qm, and MR in the relaxation-function approach (s1 = 1/τ1 and s2 = 1/τ2 are angular frequencies defining the bandwidth, MR is the relaxed modulus, and Qm is approximately the midband quality factor when Qm ≫ 1); or τ1, τ2, Qm, and MR in the creep-function approach (s1 = 1/τ1 and s2 = 1/τ2 are angular frequencies defining the bandwidth, and Qm is approximately the midband quality factor when Qm ≫ 1). In practice, it is often the case that, for a particular medium, the quality factor Q(ω0) and phase velocity c(ω0) at an angular frequency ω0 (s1 < ω0 < s2; s1 < ω0 < s2) are known from field measurements. If values are assigned to τ1 and τ2 (τ2 < τ1), or to τ1 and τ2 (τ2 < τ1), then the two remaining parameters, Qm and MR, or Qm and MR, can be obtained from Q(ω0). However, for highly attenuative media, e.g., Q(ω0) ≦ 5, Q(ω) can become highly skewed and negative at low frequencies (for the relaxation-function approach) or at high frequencies (for the creep-function approach) if this procedure is followed. A negative Q(ω) is unacceptable because it implies an increase in energy for waves propagating in a homogeneous and attenuative medium. This article shows that given (τ1, τ2, ω0) or (τ1, τ2, ω0), a lower limit of Q(ω0) exists for a bandlimited, four-parameter anelastic model. In the relaxation-function approach, the minimum permissible Q(ω0) is given by ln [(1 + ω20τ21)/(1 + ω20τ22)]/{2 arctan [ω0(τ1 − τ2)/(1 + ω20τ1τ2)]}. In the creep-function approach, the minimum permissible Q(ω0) is given by {2 ln (τ1/τ2) − ln [(1 + ω20τ21)/(1 + ω20τ22)]}/{2 arctan [ω0(τ1 − τ2)/(1 + ω20τ1τ2)]}. The more general statement that, for a given set of relaxation mechanisms, a lower limit exists for Q(ω0) is also shown to hold. Because a nearly constant midband Q cannot be achieved for highly attenuative media using a four-parameter anelastic model, a bandlimited, six-parameter anelastic model that yields a nearly constant midband Q for such media is devised; an expression for the minimum permissible Q(ω0) is given. Six-parameter anelastic models with quality factors Q ∼ 5 and Q ∼ 16, constant to 6% over the frequency range 0.5 to 200 Hz, illustrate this result. In conformity with field observations that Q(ω) for near-surface earth materials is approximately constant over a wide frequency range, the bandlimited, six-parameter anelastic models are suitable for modeling wave propagation in highly attenuative media for bandlimited time functions in engineering and exploration seismology.

RESEARCH OF METHODS FOR DECREASE OF THE CAPACITANCE RATIO IN THE STW-RESONATORS

2021 ◽  
pp. 43-56
Author(s):  
S. A. Dobershtein ◽  
N. M. Zhilin ◽  
I. V. Veremeev
Keyword(s):  
Experimental Data ◽  
Quality Factor ◽  
Quality Factors ◽  
Topology Change ◽  
Series Connection ◽  
Capacitance Ratio ◽  
And Topology

This paper presents the research of methods for decrease of the capacitance ratio in the STW-resonators without significant degradation of the quality factor by use of the external inductors and topology change: IDT division on parts and their series connection. The calculated and experimental data are presented for 416 MHz and 766 MHz STW-resonators with quality factors Q = 7000–7978. The capacitance ratio has been reduced from 1200 to 301.

Characterization of a Non-Interdigitated Comb Drive

2018 ◽  
Author(s):  
Mary Gopanchuk ◽  
Mohamed Arabi ◽  
N. Nelson-Fitzpatrick ◽  
Majed S. Al-Ghamdi ◽  
Eihab Abdel-Rahman ◽  
...  
Keyword(s):  
Quality Factor ◽  
Fundamental Frequency ◽  
High Quality Factor ◽  
Silicon On Insulator ◽  
Comb Drive ◽  
High Quality ◽  
Sensor Applications ◽  
Fabrication And Characterization

This paper reports on the design, fabrication, and characterization of non-interdigitated comb drive actuators in Silicon-on-Insulator (SOI) wafers, using a single mask surface microma-chining process. The response of the actuator is analyzed numerically and experimentally. The results show at the fundamental frequency; it behaves as a longitudinal comb drive actuator. At a higher frequency, it exhibits a high-quality factor which is appropriate for sensor applications.

A Mixing-Length Model for the Prediction of Convex Curvature Effects on Turbulent Boundary Layers

1984 ◽  
Vol 106 (1) ◽  
pp. 142-148 ◽  
Author(s):  
E. W. Adams ◽  
J. P. Johnston
Keyword(s):  
Heat Transfer ◽  
Layer Thickness ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Radius Of Curvature ◽  
Data Sets ◽  
Mixing Length ◽  
Flat Wall ◽  
Curvature Effects ◽  
Layer Thickness Ratio

A mixing-length model is developed for the prediction of turbulent boundary layers with convex streamwise curvature. For large layer thickness ratio, δ/R > 0.05, the model scales mixing length on the wall radius of curvature, R. For small δ/R, ordinary flat wall modeling is used for the mixing-length profile with curvature corrections, following the recommendations of Eide and Johnston [7]. Effects of streamwise change of curvature are considered; a strong lag from equilibrium is required when R increases downstream. Fifteen separate data sets were compared, including both hydrodynamic and heat transfer results. In this paper, six of these computations are presented and compared to experiment.

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