Optical design plays an important role in improving the performance of opto-electronic devices. However, conventional design processes using finite difference time domain (FDTD) or finite element methods are usually time and computing resource consuming, and often result in sub-optimal solutions due to an incomplete search of the parameter state space. In this paper, we propose a deep learning approach to predict and optimize the cell performance of perovskite/crystalline-silicon (c-Si) tandem solar cells. In particular, a deep neural network is established to predict the achievable short-circuit current for tandem solar cells with a given cell structure. After training on a FDTD numerical simulation data set, the proposed deep neural network achieves an accuracy of 98.3% and micro-second grade simulation time, which is an ultra-fast, highly accurate and computing resource-saving solution to investigate the current properties of tandem solar cells. Heuristic algorithms are further adopted to inversely optimize the device structure, where the optimal set of layer thicknesses is obtained to maximize the achievable short-circuit current. According to the calculated projected efficiency, the expected experimental short-circuit current and power conversion efficiency of tandem solar cells with the optimal selection of layer thickness can reach 15.79 mA cm⁻² and 23.24%, which is improved by 14.42% and 28.4%, respectively, compared to the benchmark cells.

We report synergetic strategies of combining bromine and cetyltrimethylammonium chloride additives to passivate both bulk and surface defects, leading to improved performance and stability of flexible PVSCs.

Distributed fiber-optic photoacoustic non-destructive testing (DFP-NDT) represents a paradigm shift from passive sensing to active probing, fundamentally transforming structural health monitoring through integrated fiber-based ultrasonic generation and detection capabilities. This review systematically examines DFP-NDT’s evolution by following the technology’s natural progression from fundamental principles to practical implementations. Unlike conventional approaches that require external excitation mechanisms, DFP-NDT leverages photoacoustic transducers as integrated active components where fiber-optical devices themselves generate and detect ultrasonic waves. Central to this technology are photoacoustic materials engineered to maximize conversion efficiency—from carbon nanotube-polymer composites achieving 2.74 × 10⁻² conversion efficiency to innovative MXene-based systems that combine high photothermal conversion with structural protection functionality. These materials operate within sophisticated microstructural frameworks—including tilted fiber Bragg gratings, collapsed photonic crystal fibers, and functionalized polymer coatings—that enable precise control over optical-to-thermal-to-acoustic energy conversion. Six primary distributed fiber-optic photoacoustic transducer array (DFOPTA) methodologies have been developed to transform single-point transducers into multiplexed systems, with low-frequency variants significantly extending penetration capability while maintaining high spatial resolution. Recent advances in imaging algorithms have particular emphasis on techniques specifically adapted for distributed photoacoustic data, including innovative computational frameworks that overcome traditional algorithmic limitations through sophisticated statistical modeling. Documented applications demonstrate DFP-NDT’s exceptional versatility across structural monitoring scenarios, achieving impressive performance metrics including 90 × 54 cm² coverage areas, sub-millimeter resolution, and robust operation under complex multimodal interference conditions. Despite these advances, key challenges remain in scaling multiplexing density, expanding operational robustness for extreme environments, and developing algorithms specifically optimized for simultaneous multi-source excitation. This review establishes a clear roadmap for future development where enhanced multiplexed architectures, domain-specific material innovations, and purpose-built computational frameworks will transition DFP-NDT from promising laboratory demonstrations to deployable industrial solutions for comprehensive structural integrity assessment.

Nondestructive testing (NDT) systems are critical for structural lifecycle management, yet existing algorithms struggle to address the challenges of distributed multisource systems, particularly crosstalk interference during large-area inspections. This study introduces an innovative damage detection and localization method tailored for fiber-based distributed ultrasonic excitation that uniquely enables lightweight, large-area coverage through multipoint excitation via a single optical fiber. To overcome the limitations of conventional approaches in handling distributed signal correlations, we propose a hybrid binary copula framework that optimizes copula hybridization to minimize fitting errors and precisely characterize signal dependencies. This method quantifies damage effects through correlation coefficient analysis and a novel correlation index, synergistically integrated with an energy index to form a baseline-free damage index that amplifies damage-induced signal variations. By eliminating the reliance on baseline data, this approach addresses a major bottleneck in scalable NDT applications. Experimental validation on a 2000 mm × 1000 mm × 0.5 mm aluminum plate demonstrated the system’s high-precision capability, successfully locating three coexisting damages with an average absolute error of 3.83 mm (0.31% relative error). The fusion of hybrid copula modeling and baseline-independent quantification establishes a paradigm shift for distributed NDT systems, balancing expansive coverage with sub-centimeter accuracy, which is a critical advancement in next-generation infrastructure maintenance.

The fiber optic ultrasonic transducer is resistant to electromagnetic interference and is highly multiplexable. Current optical fiber ultrasonic transducers are mainly used in medical imaging and non-destructive testing (NDT). The current ultrasonic transducer excites a weak ultrasonic signal, which limits its application in large area NDT. This work presents a method for the preparation of a large core diameter optical fiber ultrasonic transducer. Through experimental optimization, the transducer was able to excite an ultrasonic signal with a frequency of 0.449 MHz, a pulse width of about 25 μs and a peakto-peak value of 120 mV.