Optics express最新文献

Fiber-optic acoustic sensors are vital in structural health monitoring, photoacoustic spectroscopy, and biomedical applications. Achieving simultaneous measurement of quasi-static temperature and dynamic acoustic vibration with effective decoupling remains challenging. In this work, we propose an integrated fiber-optic sensor probe with dual Fabry-Perot (FP) cavities: a silicon-based cavity for temperature sensing and a diaphragm-based air cavity for acoustic pressure sensing. A novel hybrid interferometry is introduced, employing programmable modulation of a tunable Modulated grating Y-branch (MG-Y) laser to combine coarse wavelength scanning (20 kHz) at 1530 nm for acoustic measurement and dense wavelength scanning (10 Hz) at 1550 nm for temperature measurement, using a single demodulation system. Experimental results demonstrate a linear temperature response (R²=0.996) from 27°C to 56°C. Crucially, by leveraging real-time temperature compensation, the maximum acoustic pressure measurement error was reduced from 28.4% to 4.6%, validating the system's efficacy in high-precision, temperature-compensated acoustic metrology.

With the advancement of optical force research at the macroscopic scale, an increasing number of specialized devices have been developed. For such devices, multilayered dielectric coatings with ultrahigh reflectivity, together with precisely predictable optical forces, are essential for ensuring overall performance. This study establishes a theoretical framework for calculating and analyzing optical forces in multilayered coatings by integrating the layer-cavity matrix method with the Maxwell stress tensor. The framework enables precise analysis of optical force distribution with nanometer accuracy. Based on this method, specialized multilayered coatings alternating between silicon dioxide and titanium dioxide were designed and fabricated. The results show that within the 0°-8° incident-angle range, the optical force exhibits excellent robustness to variations in incident angle and polarization, with optical force uncertainty better than 2.0%. This significantly improves the applicability of high-power lasers in macroscopic optical force devices. As the incident angle increases to 30°, the angular sensitivity of the optical force gradually increases, particularly under TM polarization, which provides important references for precise control and enhancement of optical forces. This study is important for fundamental research of the optical force at the macroscopic scale, and is valuable for precision measurements and metrology applications, as well as atomic and close-to-atomic scale manufacturing applications.

Modern optical systems prioritize precision and resolution, increasing demand for large-aperture mirrors. To enhance manufacturing efficiency, we propose a multi-robot collaborative optical manufacturing technology utilizing the Preston equation. Our study correlates the rotational speed of lapping tools with material removal. For a 1450 mm diameter mirror, the process achieved a 61.96% reduction in total manufacturing time to 52 hours over eight cycles. The surface quality within the central 90% aperture was simultaneously improved, with the PV value decreasing from 80.14λ to 5.42λ (λ = 632.8 nm) and the RMS value decreasing from 8.19λ to 0.75λ.. These findings confirm that the three-robot system effectively shortens manufacturing time, providing insights for advancing intelligent optical manufacturing and enhancing production capabilities..

Multimode optical fibers, with their high spatial-mode capacity, present a promising platform for high-fidelity image transmission. However, environmental instabilities and complex input patterns often result in intricate speckle outputs, complicating accurate image reconstruction. In this work, we encode grayscale images through orbital angular momentum (OAM) mode superpositions and achieve high-fidelity reconstruction using a ResNet-based decoding network. By incorporating transfer learning, the model demonstrates strong generalization across different wavelengths and spectral linewidths, attaining a reconstruction accuracy of up to 99%. Furthermore, we develop an attention-enhanced DoubleU-Net to reconstruct complex images with rich edge structures. Experimental results verify that OAM filtering substantially enhances edge fidelity, improving the reconstruction accuracy by approximately 4% over the non-OAM case, reaching a final accuracy of 95%. These findings open avenues toward high-dimensional optical information processing, multimode fiber communications, and advanced computational imaging.

A time axis dynamic calibration method based on a reference vibration signal is proposed to address the issue of temporal resolution deviation caused by laser scanning nonlinearity during hardware compensation of distributed optical frequency domain reflectometry (OFDR) technology. By introducing a high-stability reference vibration source at the front end of the fiber under test (FUT), a mathematical model is established relating the measured frequency, theoretical frequency, and system temporal resolution. Subsequently, a time calibration factor, derived from the reference vibration frequency ratio, is innovatively introduced to dynamically calibrate the temporal resolution of original vibration signals, thereby effectively suppressing frequency measurement errors caused by time axis distortion. The experimental validation demonstrates that within the frequency range of 10-120 Hz, this method can reduce frequency measurement error to 0.56%, which is one order of magnitude lower than the pre-calibration error, significantly improving the measurement accuracy of vibration frequencies. This method provides an effective frequency error compensation solution for OFDR technology, with broad application prospects in structural health monitoring, precision instrument diagnostics, and other fields.

Quantum key distribution (QKD) allows secure key exchange based on the principles of quantum mechanics, with higher-dimensional photonic states offering enhanced channel capacity and resilience to noise. Free-space QKD is crucial for global networks where fibres are impractical, but atmospheric turbulence introduces severe states' distortions, particularly for spatial modes. Adaptive optics (AO) provides a pathway to correct these errors, though its effectiveness depends on the encoding basis. Here, we experimentally evaluate a high-speed AO system for orbital angular momentum (OAM) modes, mutually unbiased bases (MUB), and symmetric, informationally complete, positive operator-valued measures (SIC-POVM) up to dimension d = 8 in a turbulent free-space channel. While OAM states are strongly distorted, their cylindrical symmetry makes them optimally corrected by AO, yielding error rates below QKD security thresholds. MUB and SIC-POVM exhibit greater intrinsic robustness to turbulence but are less precisely corrected; however their performance remains within protocol tolerances. These results establish AO as a key enabler of secure, high-dimensional QKD and highlight the role of basis choice in optimizing resilience and correction.

We demonstrate an approach to denoise attosecond transient absorption measurements based on a predictive neural network. Transient absorption spectroscopy measures pump-induced absorption changes referenced to pump-off spectra. Strong correlations between the near-infrared and the corresponding high-harmonic radiation forming the attosecond probe enable the prediction of reference spectra simultaneously to the acquisition of the pump-on data. This ultimately leads to a significant noise reduction to within a factor of two of the detector's shot-noise limit. This improvement corresponds to achieving typical signal sensitivities up to an order of magnitude faster compared to the conventional scheme using the same setup and parameters - vastly reducing the common multi-hour acquisitions.

We report on the experimental investigation of filament-induced supercontinuum (SC) generation in a non-centrosymmetric KTA nonlinear crystal driven by hundreds of femtosecond laser pulses at 1030 nm. Driven by the s-polarized laser, a visible SC spanning from 400 nm to 900 nm is achieved when the peak power of the driving laser exceeds 5 times the critical power. Polarization analysis reveals distinct spectral and spatial profiles for the generated s- and p-polarized supercontinuum components. This work demonstrates the feasibility of controlling filament-induced nonlinear processes in nonlinear crystals, supporting their potential use in cascaded nonlinear optical applications.

Diffractive optic elements offer significant advantages in optical system design, enabling lightweight and compact architectures compared with conventional refractive and reflective components. However, accurately modeling wave-optical effects in such systems remains challenging because characteristic wavelengths of light are much smaller than the overall dimensions of typical optical assemblies. Conventional ray-tracing methods generally neglect these effects, while full-wave simulations become computationally prohibitive for large-scale systems. To overcome these limitations, we introduce a numerical implementation of the Monte Carlo ray-tracing approach based on the Huygens-Fresnel principle to predict key optical parameters, including focusing efficiency, focal spot size, and diffraction patterns with high fidelity. This approach is validated through systematic comparisons of dedicated experimental, theoretical, and numerical results, demonstrating accurate performance over a broad range of optical configurations. We further demonstrate that photon sieves incorporating large numbers of pinholes distributed across Fresnel zones can focus light into spots smaller than the smallest pinhole diameter while strongly suppressing higher diffractive orders and sidelobes. These results highlight the potential of the ray-tracing approach as a practical tool for both the design and optimization of next-generation diffractive optical elements.

In this work, a satellite cluster-to-ship free space optical (FSO) system model over the composite doubly inverted gamma-gamma (IGGG) atmospheric turbulence channel has been proposed, considering the effects of path loss and ship mobility for what we believe is the first time. To quantify the impacts of satellite cluster orbital configurations, minimum separation distance (MSD), and ship velocity in different atmospheric turbulence regimes, the closed-form expressions of outage probability (OP), average bit error rate (ABER), and ergodic capacity (EC) have been derived and verified by Monte Carlo simulations. Results show that although the OP, ABER, and EC performances of both linear and circular orbital configurations will deteriorate as the atmospheric turbulence worsens, the circular orbital configuration consistently outperforms the linear orbital configuration. Besides, reducing the MSD of the satellite cluster will further enhance the system performances while it would be degraded as the ship velocity increases. Specifically, one communication experiment between a low Earth orbit (LEO) satellite and a ground station is carried out under pointing correction and fine-tracking closed-loop control, in which the received signal-to-noise (SNR) logs are recorded to obtain the practical downlink OP, therefore verifying the proposed theoretical OP model.