Trans-scale hierarchical metasurfaces for multispectral compatible regulation of lasers, infrared light, and microwaves.

Electromagnetic scattering control of optical windows has significant challenges in improving optical transmission and compatibility, especially for multispectral and large-angle incidences, due to material and structure mismatches. This paper presents trans-scale hierarchical metasurfaces (THM) to achieve wide-angle optical transmission enhancement and electromagnetic scattering-compatible regulation in dual-band lasers, and infrared and microwave ranges. THM comprises an ultrafine hollow metal array (UHMA) and a transmission-enhanced micro-nanocone array (TMCA).

A Suppression Method for Random Errors of IFOG Based on the Decoupling of Colored Noise-Spectrum Information.

In high-precision inertial navigation systems, suppressing the random errors of a fiber-optic gyroscope is of great importance. However, the traditional rule-based autoregressive moving average modeling method, when applied in Kalman filtering considering colored noise, presents inherent disadvantages in principle, including inaccurate state equations and difficulties in state dimension expansion. To this end, the noise characteristics in the fiber-optic gyroscope signal are first deeply analyzed, a random error model form is clarified, and a new model-order determination criterion is proposed to achieve the high-precision modeling of random errors.

Fiber Optic Gyro Random Error Suppression Based on Dual Adaptive Kalman Filter.

The random error of fiber optic gyros is a critical factor affecting their measurement accuracy. However, the statistical characteristics of these errors exhibit time-varying properties, which degrade model fidelity and consequently impair the performance of random error suppression algorithms. To address these issues, this study first proposes a recursive dynamic Allan variance calculation method that effectively mitigates the poor real-time performance and spectral leakage inherent in conventional dynamic Allan variance techniques.

Improving Laser Direct Writing Overlay Precision Based on a Deep Learning Method.

This study proposes a deep learning-based method to improve overlay alignment precision in laser direct writing systems. Alignment errors arise from multiple sources in nanoscale processes, including optical aberrations, mechanical drift, and fiducial mark imperfections. A significant portion of the residual alignment error stems from the interpretation of mark coordinates by the vision system and algorithms.

Quantitative assessment of parameter requirements in a division of focal plane polarimeter.

The division of focal plane polarimeter (DoFP) is a widely utilized instrument for target detection and recognition, owing to its excellent real-time performance and compact configuration. However, due to manufacturing and integration errors, its performance when measuring the state of polarization is limited. Therefore, it is essential to understand the relationship between these error sources and their response to design, manufacture, and apply the polarimeter effectively, as this determines the degree to which errors should be controlled under different performance requirements.

Parameter Calibration of Rotating Wave Plate Polarization Detection Device Using Dual Beams.

When measuring Stokes parameters using the rotating wave plate method, the angle error of the polarizer's light transmission axis, the azimuth error of the wave plate's fast axis, and the phase delay error are key factors restricting accuracy. To address the existing calibration methods' insufficient accuracy and incomplete consideration of the error parameters, this study constructed an error-transfer analytical model for an in-depth analysis of the principle of measuring Stokes parameters using the rotating wave plate method. It also clarified the quantitative parameter relationship between the measurement, wave plate, and polarizer errors.

Time series transformer for tourism demand forecasting.

AI-based methods have been widely adopted in tourism demand forecasting. However, current AI-based methods are weak in capturing long-term dependency, and most of them lack interpretability. This study proposes a time series Transformer (Tsformer) with Encoder-Decoder architecture for tourism demand forecasting.

Infrared Small Target Detection via Modified Fast Saliency and Weighted Guided Image Filtering.

The robust detection of small targets is crucial in infrared (IR) search and tracking applications. Considering that many state-of-the-art (SOTA) methods are still unable to suppress various edges satisfactorily, especially under complex backgrounds, an effective infrared small target detection algorithm inspired by modified fast saliency and the weighted guided image filter (WGIF) is presented in this paper. Initially, the fast saliency map modulated by the steering kernel (SK) is calculated.

A Hierarchical Inverse Lithography Method Considering the Optimization and Manufacturability Limit by Gradient Descent.

Inverse lithography technology (ILT) based on the gradient descent (GD) algorithm, which is a classical local optimal method, can effectively improve the lithographic imaging fidelity. However, due to the low-pass filtering effect of the lithography imaging system, GD, although able to converge quickly, is prone to fall into the local optimum for the information in the corner region of complex patterns. Considering the high-frequency information of the corner region during the optimization process, this paper proposes a resolution layering method to improve the efficiency of GD-based ILT algorithms.

Research on High-Precision Measurement Technology of the Extinction Ratio Based on the Transparent Element Mueller Matrix.

With the widespread application of optical technology in numerous fields, the polarization performance of transmissive optical components has become increasingly crucial. The extinction ratio, an important indicator for evaluating their polarization characteristics, holds great significance for its precise detection. Aiming at the measurement of the extinction ratio of a transparent component, this study proposes a measurement method for solving the extinction ratio based on measuring the Mueller matrix of the transparent component.

Mitigating hypersonic heat barrier via direct cooling enhanced by leidenfrost inhibition.

Heat barrier, the unrestricted increase in airplane or rocket speeds caused by aerodynamic heating, which-without adequate provisions for cooling the exposed surfaces-can lead to the loss of a hypersonic vehicle's reusability, maneuverability, and cost-effectiveness. To date, indirect thermal protection methods, such as regenerative cooling, film cooling, and transpiration cooling, have proven to be complex and inefficient. Here, we propose a direct liquid cooling system to mitigate the heat barrier, utilizing a blunt-sharp structured thermal armor (STA)-a recently proposed material [36] to elevate the Leidenfrost point.

Spherical Polar Pattern Matching for Star Identification.

To endow a star sensor with strong robustness, low algorithm complexity, and a small database, this paper proposes an all-sky star identification algorithm based on spherical polar pattern matching. The proposed algorithm consists of three main steps. First, the guide star is rotated to be a polar star, and the polar and azimuth angles of neighboring stars are used as polar pattern elements of the guide star.

Dielectric Metalens Array for Simultaneous Polarization and Wavefront Mapping in the Visible Spectrum.

While traditional polarimetry effectively analyzes polarization states with bulky systems, recent advances have enabled metasurfaces to serve as compact alternatives. Metalens arrays have enabled full-polarization and phase profile determination. However, enhancing their efficiency and spatial resolution remains constrained in submetalens architectures.

Insight into the mechanism of different substituents on the zinc-oxo cluster in solubility switching.

A photoresist based on Zn(MA)(TFA) ( ≤ 6; MA and TFA are methacrylate and trifluoroacetate, respectively) shows excellent performance in extreme ultraviolet lithography (EUVL). The material is a mixture based on the ratio of MA and TFA, which could affect the production and reproducibility of the photoresist. In this paper, the structural characteristics and solubility switch mechanism of diverse compositions based on Zn(MA)(TFA) were systematically investigated using DFT calculations and molecular dynamics (MD) simulations.

Influence of Lithography Process Parameters on Continuous Surface Diffractive Optical Elements for Laser Beam Shaping.

To address the demand for laser beam-shaping techniques, we developed a one-step exposure process based on moving-mask lithography for the fabrication of a continuous-surface diffractive optical element (DOE) for laser beam shaping. The fabrication process is described in detail, and the influence of key parameters, such as pre-baking conditions, exposure gaps, development conditions, and post-baking conditions, of the lithography process on the microstructure profile of the DOE is analyzed. The reliability of the preparation method was verified through optical performance experiments.

Frequency-Decoupled Dual-Stage Inverse Lithography Optimization via Hierarchical Sampling and Morphological Enhancement.

Inverse lithography technology (ILT) plays a pivotal role in advanced semiconductor manufacturing because it enables pixel-level mask modifications, significantly enhances pattern fidelity, and expands process windows. However, traditional gradient-based ILT methods often struggle with the trade-off between imaging fidelity and mask manufacturability due to coupled optimization objectives. We propose a frequency-separated dual-stage optimization framework (FD-ILT) that strategically decouples these conflicting objectives by exploiting the inherent low-pass characteristics of lithographic systems.

The regulation scheme of a double-rotor wind turbine during operation based on the transmission modes of rotors.

Current research on double-rotor wind turbines (DRWT) primarily focuses on aerodynamic performance and wake characteristics. Addressing the specific control challenges during operation, this study first establishes a geometric model of the Counter-rotating Double-Rotor Wind Turbine (C-DRWT) and an integrated drivetrain model from the dual rotors to the gearbox. Subsequently, based on the structural characteristics of C-DRWT and its operational wind speed range, three gearbox operating modes and three transmission configurations for the dual rotors are defined under necessary assumptions (e.

Temperature-dependent modeling and enhanced measurement of ultrasonic velocity in LAS glass-ceramics.

LiO-AlO-SiO (LAS) glass-ceramics are widely used in many fields owing to their ultra-low coefficient of thermal expansion (CTE). The ultrasonic velocity method shows potential as an effective method for the nondestructive measurement of the CTE and CTE homogeneity of large LAS glass-ceramics. To further improve the precision of ultrasonic velocity (c) measurements of LAS glass-ceramics and reveal the effect of the temperature (T) on c, an improved correlation method to rapidly determine the time of flight (TOF) in LAS glass-ceramics is proposed.

Dispersion-engineered spin photonics based on folded-path metasurfaces.

Spin photonics revolutionizes photonic technology by enabling precise manipulation of photon spin states, with spin-decoupled metasurfaces emerging as pivotal in complex optical field manipulation. Here, we propose a folded-path metasurface concept that enables independent dispersion and phase control of two opposite spin states, effectively overcoming the limitations of spin photonics in achieving broadband decoupling and higher integration levels. This advanced dispersion engineering is achieved by modifying the equivalent length of a folded path, generated by a virtual reflective surface, in contrast to previous methods that depended on effective refractive index control by altering structural geometries.

Large-Scale Fabrication of 5 nm Plasmonic Hybrid Nanoslit Arrays.

Surface plasmon resonance harnessed through nanometer-scale metallic gaps generates intense near-fields, unlocking vast potential for applications in nanophotonics and biosensing. However, the scarcity of scalable and reproducible nanofabrication techniques capable of achieving a sub-10 nm gap remains a significant barrier to widespread implementation. Here, we present a high-throughput method combining deep-UV interference lithography, molecular self-assembly, and peeling to fabricate large-scale arrays of an ∼ 5 nm Au-Ag hybrid nanoslit.

Multi-Scale Fusion Underwater Image Enhancement Based on HSV Color Space Equalization.

Meeting the escalating demand for high-quality underwater imagery poses a significant challenge due to light absorption and scattering in water, resulting in color distortion and reduced contrast. This study presents an innovative approach for enhancing underwater images, combining color correction, HSV color space equalization, and multi-scale fusion techniques. Initially, automatic contrast adjustment and improved white balance corrected color bias; this was followed by saturation and value equalization in the HSV space to enhance brightness and saturation.

Scaled transverse translation by planar optical elements for sub-pixel sampling and remote super-resolution imaging.

High resolution imaging represents a relentless pursuit within the field of optical system. Multi-frame super-resolution (SR) is an effective method for enhancing sampling density, while it heavily relies on sub-pixel scale displacement of a bulky camera. Based on the symmetric transformation of quadratic-phase metasurface, we propose scaled transverse translation (STT) utilizing planar optical elements (POEs) to facilitate sub-pixel sampling and remote super-resolution imaging.

Free-form catenary-inspired meta-couplers for ultra-high or broadband vertical coupling.

Metasurface-assisted waveguide couplers, or meta-couplers, innovatively link free-space optics with on-chip devices, offering flexibility for polarization and wavelength (de)multiplexing, mode-selective coupling, and guided mode manipulation. However, conventional meta-couplers still face challenges with low coupling efficiency and narrow bandwidth due to critical near-field coupling caused by waveguide constraints and unit-cell-based design approach, which cannot be accurately addressed using traditional design methods. In this paper, quasi-continuous dielectric catenary arrays are first employed to enhance efficiency and bandwidth by addressing adjacent coupling issues of discrete metasurface.

Digital Frequency-Domain MIMO Equalizer Enabling Six-LP-Mode Strong-Coupling IM/DD MDM Optical Transmission System.

Mode division multiplexing (MDM) techniques provide significant enhancement of the capacity of optical intensity modulation and direct detection (IM/DD) short-reach communication systems, like the datacenter interconnection scenarios. While the introduction of multiple modes leads to mode coupling that will extremely deteriorate the received signals, two approaches have been explored to address this issue: one involves the application of all-link weakly coupled components to suppress modal crosstalk, while the other utilizes optical multiple-input-multiple-output (MIMO) equalizers based on optical devices for signal decoupling. However, pure digital signal processing (DSP)-based schemes for mode decoupling in IM/DD MDM systems with strong mode coupling remain unexplored.

Acceleration control in a dual-stage inertial stabilization system using embedded-parallel-based repetitive-peak compensation.

Acceleration control demonstrates high sensitivity to nonlinear vibrations in the inertial stabilized motion, usually serving as the preferred choice for observation systems in applications like space optical communications, enabling precise tracking and pointing. However, the stabilization performance is limited by the inadequate gain at mid- to high-frequencies in conventional acceleration control, as well as other nonlinear factors like flexibility and backlash. In this paper, an embedded-parallel-based stabilization methodology is proposed for an acceleration-based dual-stage inertial system to achieve additional notch shaping of the sensitivity function.