Design and simulation of a silicon-based hybrid integrated optical gyroscope system

By combining a silicon-based lithium niobate modulator and a silicon-based Si3N4resonator with silicon-based photonics technology,a highly systematic design of a hybrid integrated optical gyroscope with enhanced reciprocity sensitivity and a dual micro-ring structure is proposed for the first time in this paper.The relationship between the device's structural parameters and optical performance is also analyzed by constructing a complete simulation link,which provides a theoretical design reference to improve the system's sensitivity.When the wavelength is 1550 nm,the conversion frequency of the dual-ring optical path is 50 MHz,the coupling coefficient is 0.2,and the radius R is 1000μm,the quality factor of the silicon-based Si_(3)N_(4)resonator is 2.58×10^(5),which is 1.58 times that of the silicon-on-insulator resonator.Moreover,the effective number of times the light travels around the ring before leaving the micro-ring is 5.93,which is 1.62 times that of the silicon-on-insulator resonator.The work fits the gyro dynamic output diagram,and solves the problem of low sensitivity at low speed by setting the phase offset.This results provide a basis for the further optimization of design and chip processing of the integrated optical gyroscope.

Interface effect on superlattice quality and optical properties of InAs/GaSb type-Ⅱ superlattices grown by molecular beam epitaxy

We systematically investigate the influence of InSb interface(IF)engineering on the crystal quality and optical properties of strain-balanced InAs/GaSb type-Ⅱsuperlattices(T2SLs).The type-Ⅱsuperlattice structure is 120 periods InAs(8 ML)/GaSb(6 ML)with different thicknesses of InSb interface grown by molecular beam epitaxy(MBE).The highresolution x-ray diffraction(XRD)curves display sharp satellite peaks,and the narrow full width at half maximum(FWHM)of the 0th is only 30-39 arcsec.From high-resolution cross-sectional transmission electron microscopy(HRTEM)characterization,the InSb heterointerfaces and the clear spatial separation between the InAs and GaSb layers can be more intuitively distinguished.As the InSb interface thickness increases,the compressive strain increases,and the surface“bright spots”appear to be more apparent from the atomic force microscopy(AFM)results.Also,photoluminescence(PL)measurements verify that,with the increase in the strain,the bandgap of the superlattice narrows.By optimizing the InSb interface,a high-quality crystal with a well-defined surface and interface is obtained with a PL wavelength of 4.78μm,which can be used for mid-wave infrared(MWIR)detection.

Development of a biomechanical model for dynamic occlusal stress analysis

The use of traditional finite element method(FEM)in occlusal stress analysis is limited due to the complexity of musculature simulation.The present purpose was to develop a displacement boundary condition(DBC)-FEM,which evaded the muscle factor,to predict the dynamic occlusal stress.The geometry of the DBC-FEM was developed based on the scanned plastic casts obtained from a volunteer.The electrognathographic and video recorded jaw positional messages were adopted to analyze the dynamic occlusal stress.The volunteer exhibited asymmetrical lateral movements,so that the occlusal stress was further analyzed by using the parameters obtained from the right-side eccentric movement,which was 6.9 mm long,in the stress task of the left-side eccentric movement,which was 4.1 mm long.Further,virtual occlusion modification was performed by using the carving tool software aiming to improve the occlusal morphology at the loading sites.T-Scan Occlusal System was used as a control of the in vivo detection for the location and strength of the occlusal contacts.Data obtained from the calculation using the present developed DBC-FEM indicated that the stress distribution on the dental surface changed dynamically with the occlusal contacts.Consistent with the T-Scan recordings,the right-side molars always showed contacts and higher levels of stress.Replacing the leftside eccentric movement trace by the right-side one enhanced the simulated stress on the right-side molars while modification of the right-side molars reduced the simulated stress.The present DBC-FEM offers a creative approach for pragmatic occlusion stress prediction.

Magnetic shielding property for cylinder with circular, square, and equilateral triangle holes

The shielding property of cylinder with circular, square, and equilateral triangle holes was investigated by finite element analysis(FEA). The hole area(S_(hole)) plays an important role in magnetic circuit on the surface of cylinder. When Sholeis less than the critical area(S_(H)), cylinder with three shapes of holes obtained the same remanent magnetization inside,indicating that the shielding property is unaffected by the shape of the hole. Hence, high-permeability material is the major path of the magnetic field. On the condition of S_(hole)> S_(H), the sequence of the shielding property is equilateral triangle >square > circular, resulting from magnetoresistance of leakage flux in air dielectric. Besides, the anisotropy of shielding property caused by hole structural differences of the cylinder is evaluated. We find that a good shielding effectiveness is gained in the radial direction, compared with the axis direction. This research focuses on providing a theoretical support for the design of magnetic shield and improvement on the magnetic shielding ability.

Effect of growth interruption time on the quality of InAs/GaSb type-Ⅱ superlattice grown by molecular beam epitaxy

We systematically investigate the influence of growth interruption time on the properties of In As/Ga Sb type-II superlattices(T2SLs) epitaxial materials grown by molecular beam epitaxy(MBE). X-ray diffraction(XRD) and atomic force microscope(AFM) are used to characterize the material quality and morphology. The full width at half maximum(FWHM) of the XRD 0th satellite peaks ranges from 32″ to 41″, and the root mean square(RMS) roughness on a 5 μm×5 μm scan area is 0.2 nm. Photoluminescence(PL) test is used to reveal the influence of the growth interruption time on the optical property. Grazing incidence X-ray reflectivity(GIXRR) measurements are performed to analyze the roughness of the interface. The interface roughness(0.24 nm) is optimal when the interruption time is 0.5 s. The crystal quality of T2SLs can be optimized with appropriate interruption time by MBE, which is a guide for the material epitaxy of high performance T2SL infrared detector.

Efficient application of carbon-based nanomaterials for high-performance perovskite solar cells

The power conversion efficiency of perovskite solar cells(PSCs) has rapidly risen from 3.8% to over25.0% in just about one decade, which attracts a lot of attention from the scientific and engineering communities.However, some challenges remain, hindering the progress of commercialization such as intrinsic and extrinsic(environmental) stabilities, which can be improved by an interface and structural engineering. In recent years, some reports indicate that the interfacial engineering using carbon-based nanomaterials additives plays a crucial role in the process of charge carriers and perovskite crystal growth and thereby enhances device performance and operational stability. Here, we review the development of the varieties of carbon-based nanomaterials applications in PSCs, such as hole-transporting layers(HTLs), electron-transporting layers(ETLs), perovskite bulk layer, and their interfaces.Furthermore, we proposed a further suggestion about the optimized preparation conditions for the preparation of PSCs, which may inspire the researcher to discover, design,and manufacture the more efficient perovskite solar cells in academic and industry.

Structure induced wide range wettability:Controlled surface of micro-nano/nano structured copper films for enhanced interface

The wettability of materials used in the production of devices employed in various technological domains have attracted significant attentions.Therefore,it is important to design the surfaces of these materials such that they can provide the required surface free energy and simplify the interfacial structure.Herein,various Cu films with a highly controllable surface wettability and a wide range of contact angles ranging from 6°to 152°were fabricated,and the corresponding mechanism was discussed.A wide range of wettability was realized by controlling the surface structure of the Cu film.The nanogap structure of the vertical nanowire-array film led to a high surface free energy.Similarly,the oblique nanowirearray film increased the surface free energy;however,the surface free energy was dependent on the size of the nanowires rather than on the nanogaps owing to the crystallinity of the film.Additionally,cluster-nanowire-array films were designed to realize a wettability transition from hydrophilicity to hydrophobicity with a constant surface free energy.The Cu foam possessed a superhydrophilic surface owing to its high porosity,whereas the cluster-nanoparticle structure possessed a superhydrophobic surface.In addition,we noted that the structure-induced wettability played an important role in tuning the semiconductor and metal interfacial stress and simplifying the interfacial structure.Furthermore,the outstanding electrical conductivity of the Cu films indicates its promising potential as an electrode.The structure-induced wettability proposed in this study can be applied for a wide range of materials,particularly for films used for advanced applications.

Optimization of optical convolution kernel of optoelectronic hybrid convolution neural network

To enhance the optical computation’s utilization efficiency, we develop an optimization method for optical convolution kernel in the optoelectronic hybrid convolution neural network(OHCNN). To comply with the actual calculation process, the convolution kernel is expanded from single-channel to two-channel, containing positive and negative weights. The Fashion-MNIST dataset is used to test the network architecture’s accuracy, and the accuracy is improved by 7.5% with the optimized optical convolution kernel. The energy efficiency ratio(EER) of two-channel network is 46.7% higher than that of the single-channel network, and it is 2.53 times of that of traditional electronic products.

Mid-wavelength InAs/GaSb type-Ⅱ superlattice barrier detector with nBn design and M barrier

This study reports the performance of an InAs/GaSb type-Ⅱ superlattices(T2SLs) detector with nBn structure for mid-wavelength infrared(MWIR) detection. An electronic band structure of M barrier is calculated using 8-band k·p method, and the nBn structure is designed with the M barrier. The detector is prepared by wet etching, which is simple in manufacturing process. X-ray diffraction(XRD) and atomic force microscope(AFM) characteristics indicate that the detector material has good crystal quality and surface morphology. The saturation bias of the spectral response measurements at 77 K is 300 m V, and the device is promising to work at a temperature of 140 K. Energy gap of T2SLs versus temperature is fitted by the Varshni curve, and zero temperature bandgap Eg(0), empirical coefficients α and β are extracted. A dark current density of 3.2×10-5A/cm2and differential resistance area(RA) product of 1.0×104Ω·cm2are measured at 77 K. The dominant mechanism of dark current at different temperature ranges is analyzed. The device with a 50% cutoff wavelength of 4.68 μm exhibits a responsivity of 0.6 A/W, a topside illuminated quantum efficiency of 20% without antireflection coating(ARC), and a detectivity of 9.17×1011cm·Hz1/2/W at 77 K and 0.3 V.

AWG-based large dynamic range fiber Bragg grating interrogation system

Arrayed waveguide gratings(AWGs) are extensively employed in fiber Bragg grating(FBG) interrogation systems due to their compact size, lightweight nature, and excellent interrogation performance. The resolution and total measurement range of AWG-based FBG interrogation systems are constrained by the output properties of AWG. We proposed an AWG-based large dynamic range interrogation system. The temperature dependence of AWG is exploited to achieve continuous interrogation. The test results show that the interrogation system has a dynamic range of 28.67 nm, an interrogation accuracy better than 25 pm, and a wavelength resolution of 6 pm.

Silicon waveguide-based single cavity Fano resonance temperature sensor

A compact Fano resonant temperature sensor composed of a micro-ring resonator(MRR)coupled double-T-shaped waveguide is developed.The coupling gap and coefficient of the device are optimized by the finite difference time domain(FDTD)method.The maximum slope ratio(SR)of the MRR-coupled single-T-shaped waveguide is-2.13 d B/nm.The SR of the double-T-shaped waveguide is-49.69 d B/nm which is 23 times that of the single-T-shaped waveguide.The simulation results show that the temperature sensitivity of optical intensity decreases with increasing temperature in the range from 303.6 K to 343.8 K.The wavelength-temperature sensitivity of the double-T-shaped waveguide microring is 76.5 pm/K.After introducing the double-T-shaped waveguide structure,the device’s performance is greatly improved,and the double-T-shaped waveguide has a good application prospect as a temperature sensor.