The [001]-oriented Pr3+ doped Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (Pr-PMN-PT) thin films with a composition near the morphotropic phase boundary (MPB) were synthesized by a sol–gel method. The crystal structure was characterized using X-ray diffraction. It was found that a single perovskite phase was achieved in Pr-PMN-PT thin films annealed at 650 °C for 3 min. The dielectric constant (εr) value was 2400 in 2.5% Pr-PMN-PT thin films at room temperature, 110% higher than that of pure PMN-PT samples. Through 2.5% Pr3+ doping, remanent polarization (Pr) and coercive field (Ec) values increased from 11.5 μC/cm2 and 35 kV/cm to 17.3 μC/cm2 and 63.5 kV/cm, respectively, in PMN-PT thin films. The leakage current densities of pure and 2.5% Pr-PMN-PT thin films were on the order of 1.24 × 10−4 A/cm2 and 5.8 × 10−5 A/cm2, respectively, at 100 kV/cm. A high pyroelectric coefficient (py) with a value of 167 μC/m2K was obtained in 2.5% Pr-PMN-PT thin films on Si substrate, which makes this material suitable for application in infrared detectors.

A micro-pyramid structured thin film with a broad-band infrared antireflection property is designed and fabricated by using the single-point diamond turning (SPDT) technique and combined with nano-imprint lithography (NIL). A structure with dimensions of 10 µm pitch and 5 µm height is transferred from the copper mold to the silicon nitride optical film by using NIL and proportional inductively-coupled plasma (ICP) etching. Reflectance of the micro-optical surface is reduced below 1.0% over the infrared spectral range (800-2500 nm). A finite-difference-time-domain (FDTD) analysis indicates that this micro-structure can localize photons and enhance the absorption inside the micro-pyramid at long wavelengths. As described above, the micro-pyramid array has been integrated in an optical film successfully. Distinguishing from the traditional micro-optical components, considering the effect of refraction and diffraction, it is a valuable and flexible method to take account of the interference effect of optical film.

The surface acoustic wave (SAW) gyroscopic effect in an interdigital transducer (IDT) deposited on a piezoelectric substrate is different from that in the piezoelectric substrate due to a reflection induced by IDT. In this work, an extended coupling-of-mode (COM) model including the gyroscopic effect and the reflection was developed to analyze the SAW gyroscopic effect. First, dispersion characteristics parameters of SAW were fitted according to the data derived using the finite element method (FEM). Then, variations of stop band edge frequency were calculated using the extended COM theory by integrating dispersion characteristics parameters into the COM model. We compared its results with those obtained via FEM analysis to confirm the proposed model’s validity. We found that the variation in stop band edge frequency related to gyroscope effect reached the maximum value with a zero reflectivity value. For split IDT, the sensitivity of gyroscope effect is 0.036 Hz/rad/s with a lower than 1% normalized thickness. Conversely, the value of sensitivity was almost zero for bidirectional IDT and electrode width controlled single-phase unidirectional transducer (EWC/SPUDT).

In order to realize the following two goals including high electromechanical coupling coefficient (K2) and zero temperature coefficient of frequency (TCF) in a surface acoustic wave (SAW) device, the propagation characteristics of shear-horizontal type (SH-type) boundary waves in the Si/SiO2/Al/LiTaO3 “sandwich” structure are investigated by the three dimensional (3D) finite element method (FEM). The influences of layer SiO2 with different thickness (h) on the SH-type boundary waves characteristics, including the phase velocity (vp), reflection coefficient (kp), K2 and TCF, are theoretically analyzed. The results present that the SH-type boundary wave has a maximum K2 of 4.45% at h/λ=0.62 and has a zero TCF by adjusting h/λ to 0.69. Owing to the acoustic energy distribution approaching to the SiO2/LiTaO3 boundary, the size of Love wave based devices can be reduced to a few wavelength thickness of Si and 36°YX- LiTaO3 crystals, and which also give an opportunity to be integrated onto one chip with subsequent electronic circuits.

To obtain a high-performance surface acoustic wave (SAW) gyroscope substrate, the propagation characteristics and gyroscopic effect of Rayleigh waves in a 128°Y–X LiNbO3/SiO2/Si (LNOI) functional substrate were investigated with a three-dimensional finite element method. The influence of LNOI structural parameters on Rayleigh wave characteristics, including the phase velocity (vp), electromechanical coupling coefficient (K2) and temperature coefficient of frequency (TCF), were analyzed. The results demonstrate that the SiO2 layer compensates for the negative TCF of 128°Y–X LiNbO3 and enhances the K2 of the LNOI substrate. The Rayleigh wave velocity change of the LNOI substrate after rotations in different directions was studied. The gyroscope gain factor (η) represents the strength of the gyroscopic effect in the differential traveling wave SAW gyroscope and is defined. The ηy and ηz of the LNOI substrate with different structural parameters were investigated. Finally, an LNOI substrate with an hLN/λ of 0.2 and an hSiO2/λ of 0.05 was obtained by balancing the characteristic parameters, with a K2 of 3.96%, TCF of −18.75 ppm/°C and ηy of 0.26. The LNOI substrate has a better gyroscopic effect and temperature stability than the 128°Y–X LiNbO3 crystal. The LNOI substrate meets device miniaturization and integration needs.

In this paper, synthetically using refraction, diffraction, and interference effects to achieve free manipulation of the focused optical field, we firstly present a photonic nanojet (PNJ) generated by a micropyramid, which is combined with multilayer thin films. The theory of total internal reflection (TIR) was creatively used to design the base angle of the micropyramid, and the size parameters and material properties of the microstructure were deduced via the expected optical field distribution. The as-designed bilayer micropyramid array was fabricated by using the single-point diamond turning (SPDT) technique, nanoimprint lithography (NIL), and proportional inductively coupled plasma (ICP) etching. After the investigation, the results of optical field measurement were highly consistent with those of the numerical simulation, and they were both within the theoretical calculation range. The bilayer micropyramid array PNJ enhanced the interference effect of incident and scattered fields; thus, the intensity of the focused light field reached 33.8-times that of the initial light, and the range of the focused light field was extended to 10.08λ. Moreover, the full width at half maximum (FWHM) of the focal spot achieved was 0.6λ, which was close to the diffraction limit.

The polarization multiplexing technique is a well-established method that improves the communication capacity of an optical system. In this paper, we designed orthogonal linear and circular polarization multiplexing metalens using a library of rectangle TiO2 nanostructures. The former can independently focus x- and y-linearly polarized incident lights to designed positions with a focusing efficiency of 53.81% and 51.56%, respectively, whereas the latter with two preset focal points can independently control left and right circularly polarized incident lights with a focusing efficiency of 42.45% and 42.46%, respectively. We also show that both metalenses can produce diffraction-limited focal spots for four polarization states with no obvious distortion, which opens up new applications in polarization imaging and polarization detection.

The current structured light projector is generally large in size. In order to realize a compact and small-sized module, this paper proposes to substitute the conventional refractive lenses with the most popular meta-lenses to achieve compactness. This paper focuses on the analysis of the metalens performance requirements, design methods and simulation results. Varying diameters of these nano-pillar structures are used to adjust the phase of the electromagnetic wave to realize flat lens. Two types of all-dielectric meta-lenses are designed for using in ultra-compact structured light projector. Parameters of two meta-lenses at wavelength of 850nm are depicted as follows: the focal length f=500um, aperture size D=100um, numerical aperture NA=0.1, FWHM=0.323λ and the focal length is f=50um, aperture size is D=100um, numerical aperture is about NA=0.7, FWHM=0.598λ, respectively. At last, simulation results show that this solution can achieve an ultra-compact structured light projector, which is 77% smaller than the traditional technology.