Optics express最新文献

TFSolver is a Python toolkit for the electromagnetic calculation of planar isotropic and anisotropic multilayer thin films. This toolkit uses the PyTorch library to implement the 4 × 4 matrix method. One of the key advantages of TFSolver is its ability to perform parallel simulations for multilayer thin-film stacks across a broad spectral range and various incident angles, significantly speeding up the simulation process. Additionally, it supports GPU acceleration, further improving computational efficiency. Another notable feature is its support for automatic differentiation, which enables gradient-based optimization tasks. Furthermore, TFSolver can be integrated with deep learning algorithms, supporting emerging applications such as physics-guided inverse design. Here, we first introduce the formulation and the usage of TFSolver, compare it with existing toolkits and software, and validate its computational accuracy and efficiency. With its accelerated computational performance and automatic differentiation, TFSolver is a valuable toolkit for the characterization and design of various isotropic and anisotropic materials and multilayer thin-film devices.

The detection of trace gases is crucial in environmental monitoring, industrial safety, and medical diagnostics. Optical sensing technologies, particularly those leveraging photothermal spectroscopy, offer high sensitivity and selectivity, enabling the identification of gases based on their unique absorption spectra. Among these, photothermal interferometry offers exceptional sensitivity due to its use of an interferometric signal transducer. In this work, we performed numerical simulations to systematically explore the influence of cavity geometry and mirror curvature on sensitivity. This guided the design of the most sensitive configurations. To validate the theoretical enhancement, we present a systematic comparison of 18 Fabry-Pérot interferometers (FPI) fabricated via two-photon polymerization (2PP) directly onto optical fiber-tips. These FPIs were rapidly prototyped using a commercial 2PP printer. They span three cavity lengths (110, 200, and 300 µm), each configured with flat or spherical mirrors. Single-cavity and Vernier-enhanced FPIs were implemented. The latter were also modified by gold coating of the terminal interface to enhance reflectivity. We evaluated the sensitivity optimization for collinear photothermal spectroscopy in a wavelength modulation setup. By exploiting the Vernier effect and tailored cavity geometries, we demonstrate a 12-fold improvement in the photothermal 2f-signal compared to a single-cavity FPI configuration. This highlights the versatility of 2PP-printed fiber-tip FPIs for next-generation trace gas sensors.

Analog optical computing has garnered significant attention owing to its ultra-high speed, ultra-low power consumption, and parallel processing capabilities. Recent advances in Fourier optics and metasurface technology have enabled the realization of on-chip optical differentiators, integrators, and differential equation solvers. However, conventional devices are constrained to a single function once fabricated, lacking dynamic reconfigurability. In this study, we propose an on-chip reconfigurable analog optical computing device based on a silicon-on-insulator platform. The design employs a modified 4f system, where the air-slit structure in the computational metasurface is replaced with phase-change material (Ge₂Sb₂Te₅ and Sb₂S₃) array blocks. By independently controlling the phase transition of each block, we demonstrate dynamic switching between differentiation, integration, ordinary differential equation solving, and integro-differential equation (IDE) solving within a fixed structure. The IDE solving is first implemented on-chip. Theoretically, this device can be reconfigured for arbitrary computational operations. Our approach offers a promising solution for the large-scale integration of optical computing chips, with potential applications in high-speed, complex computations for artificial intelligence.

Most displacement sensors offer high resolution but suffer from limited sensitivity and measurement range. Typically, increasing the range results in a reduction in both resolution and sensitivity. This study presents a novel displacement sensor based on a spiral-structured polymer optical fiber that operates through intensity modulation via bend-induced coupling. Controlled spiral bending generates radiative loss, which is coupled by strategically positioned secondary fibers. The sensor comprises two segments: a spiral-shaped primary fiber that generates controlled radiative losses through macro-bending, and a vertically movable secondary fiber that couples the radiated optical power to quantify displacement. A custom 3D-printed experimental platform with a guiding groove was developed to ensure precise alignment and minimize axial motion. Experimental results demonstrate a displacement measurement range of up to 20 mm, with high sensitivity of 3.26μW/mm, resolution (30.67 nm), excellent repeatability, and stable response. The proposed sensor provides a compact, cost-effective, and flexible solution for distributed displacement monitoring in various applications.

Pulse shapers are widely utilized in two-dimensional (2D) spectroscopy to generate a pump pulse pair with variable time delay and relative carrier-envelope phase. Their use in action-detected 2D spectroscopy has recently garnered interest due to the compatibility with microscopy and potentially higher sensitivity down to the single-molecule level. However, under the conditions necessary for action-detected 2D spectroscopy experiments, pulse shapers are prone to exhibiting nonlinear responses, obscuring the molecular response. Here, we illustrate the potential sources of nonlinearity in an acousto-optic programmable dispersive filter (AOPDF) and demonstrate methods to account for them in data collection and processing, enabling artifact-free action-detected 2D spectroscopy measurements.

In condensed matter physics, the study of topological materials has recently extended to the topological chirality of Weyl nodes in type-II Weyl semimetals such as TaIrTe₄. High-order harmonic generation under strong-field excitation serves as an all-optical probe of their unique electronic topology. Here, we report the high-order harmonic generation in TaIrTe₄, which exhibits a strong handedness-dependent asymmetry in the ellipticity dependence of harmonic yield, as well as the continuously tunable polarization states of harmonics driven by an elliptically polarized laser. By analyzing the underlying mechanisms, we identify the imprint of the distinct properties of TaIrTe₄ within the harmonic emissions, including the broken inversion symmetry, the tilted chiral Weyl cone and Berry curvature. Our results establish the potential possibility of high-order harmonic generation as a sensitive probe for complex topological properties in quantum materials under strong-field conditions.

All-optical neural networks (AONNs) promise transformative gains in speed and energy efficiency for artificial intelligence (AI) by leveraging light's intrinsic parallelism and wave nature. However, their scalability has been fundamentally limited by the high power requirements of conventional nonlinear optical elements. Here, we present a low-power nonlinear activation scheme based on a three-level quantum system driven by dual laser fields. This platform introduces a two-channel nonlinear activation matrix with self- and cross-nonlinearities, enabling true multi-input, multi-output optical processing. The system supports tunable activation behaviors, including sigmoid and ReLU functions, at ultralow power levels (17 μW per neuron). We validate our approach through theoretical modeling and experimental demonstration in rubidium vapor cells, showing the feasibility of scaling to deep AONNs with millions of neurons operating under 20 W of total optical power. Crucially, we demonstrate the all-optical generation of gradient-like signals with backpropagation, paving the way for all-optical training. These results mark a significant advance toward scalable, high-speed, and energy-efficient optical AI hardware.

The potential for realizing fast, energy-efficient integrated photonic memory and computing devices developed from the nanoscale light-squeezing and electric-field enhancing capability of plasmonic resonant structures and the intrinsic tuneability of chalcogenide phase-change materials is explored. We concentrate on designs that should be readily manufacturable, comprising a plasmonic dimer-bar nanoantenna deposited on top of a phase-change cell, itself deposited on top of an integrated photonic waveguide. Device optical properties and switching behavior are determined by a combination of finite-element thermo-optic and bespoke phase-change computational models. The results show that suitably designed devices can achieve switching energies in the tens of pico-Joule range and switching speeds in the tens of nanosecond range, a very considerable improvement over conventional designs, and showing a good trade-off between the device performance and fabrication complexity.

After publication of [Opt. Express33(21), 44226 (2025)10.1364/OE.575241], the authors noticed that Fig. 9 in [1] was incorrectly placed as Fig. 8. This erratum corrects Fig. 9 in [1] based on the "Author Response" file archived in the Prism system. All the conclusions remain unchanged after the correction.

VIPA-based Brillouin spectrometers have been widely used in Brillouin microscopy systems for extracting the Brillouin frequency shift. Enhancing the measurement precision of Brillouin shift is essential for high-resolution 3D imaging. In this work, we propose a novel 2D dispersion model for a double-stage orthogonal VIPA-based spectrometer based on the angular spectrum of plane waves. Using the derived dispersion equation, the Brillouin frequency shift can be determined through quadratic and cubic function approximations. To validate the proposed dispersion model, we develop a confocal Brillouin system by leveraging the double-stage orthogonal VIPA-based spectrometer to measure the Brillouin frequency shifts of pure water and methanol samples. The results show that the Brillouin measurements of water and methanol present good robustness and high precision at different integration times of EMCCD camera. The standard deviation of the Brillouin shift is <5.0 MHz and the line width of histogram is <10 MHz when the camera integration time exceeds 0.1 s under a laser power of 10 mW. The proposed method features instantaneous self-calibration and eliminates the need for standard samples to determine Brillouin shifts, thereby significantly shortening the measurement time. This study is crucial for the future development and application of 3D elastography of biological tissues utilizing the Brillouin microscopy technique.