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 (v_p), 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 η_y and η_z of the LNOI substrate with different structural parameters were investigated. Finally, an LNOI substrate with an h_LN/λ of 0.2 and an h_SiO2/λ of 0.05 was obtained by balancing the characteristic parameters, with a K² of 3.96%, TCF of −18.75 ppm/°C and η_y 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.

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 films of vinylidene fluoride and trifluoroethylene (P(VDF-TrFE)) are widely used in piezoelectric tactile sensors, vibration energy harvesters, optical frequency conversion materials and organic photo-voltaic devices because of high electroactive, good optical and nonlinear optical properties, respectively. In this work, the multilayer structured ultrathin films were fabricated by the Langmuir–Blodgett technique, and the thickness per layer can be controlled accurately. It was found that as the collapse pressure of P(VDF-TrFE) (25:75) and the optimal dipping value are 60~70 mN/m and 15 mN/m, respectively, a high-density film can be obtained due to the compression of molecules. The surface topography and optical properties of the LB films were characterized by X-ray diffraction, white light interferometer and variable-angle spectrum ellipsometer. It was observed that the films are transparent in the visible region and IR-band, but show a high absorption in the UV band. Besides, the transmittance of the films ranges from 50% to 85% in the visible region, and it linearly decreases with the number of monolayers. The average thickness of per deposition layer is 2.447 nm, 2.688 nm and 2.072 nm, respectively, under three measurement methods. The calculated refractive index ranged from 1.443 to 1.598 (600~650 nm) by the Cauchy-model.

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.

Analysis ready data (ARD) has recently become a popular standard for medium-resolution satellite images. The most representative datasets, namely Sentinel-2 Level-2A products and Landsat Collection 2 Level-2 Science Products, have met ARD standards, with public access. The Chinese Gaofen (GF) series Level-1A wide field of view (WFV) product, which has a similar ground sampling distance (GSD) to Sentinel-2 Level-2A products, is open to the public for its scenes and rational function model (RFM). However, the lower geometric processing accuracy of WFV products of approximately 3-pixel geolocation deviation restricts their wide application and further development towards ARD. The causes of low accuracy are twofold, namely the impact of calibration errors and the inaccuracy of the exterior orientation parameters. In terms of improving the accuracy of RFM, bundle adjustment and the bias compensation model (BCM) are currently the most widely accepted methods. However, existing approaches do not account for the imaging characteristics of WFV scenes, which are only for narrow field-of-view scenes and do not help with nonlinear internal distortions. To address the shortcomings of these methods, a joint orientation method for WFV cameras is proposed in this study. Owing to the high level of geometric accuracy of Sentinel-2 Level-1C reference scenes, this study analyzed the expression of WFV camera attitude errors on the image side. A polynomial exterior orientation model suitable for WFV cameras is also provided. We performed a refined calibration of the nonlinear internal distortions using multi-temporal GF-6 Level-1A WFV images, because of the additional error introduced by the cross-track inconsistency of the Sentinel-2 reference data. The method developed in this study has been experimentally verified to achieve satisfactory geometric positioning accuracy with GF-6 WFV products from 3-pixel to 0.3-pixel (5 m). This study allows optimization of the geometric performance of GF-6 Level-1A WFV products to the level of Sentinel-2 Level-1C products, which is of considerable importance in developing GF WFV images to ARD.

The [001]-oriented Pr³⁺ doped Pb(Mg_1/3Nb_2/3)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 (ε_r) 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 (P_r) and coercive field (E_c) 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 (p_y) 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.