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Nondiffracting Bessel surface plasmon polariton (SPP) beams, which have unique self-healing, non-divergence, and linear transmission properties, have charming applications in plasmonic devices and on-chip interconnection circuits. Here we first realize, to the best of our knowledge, the ultrafast control and imaging of the Bessel SPP pulse on the nano-femto scale in the experiment. We demonstrate ultrafast control of Bessel SPP pulse switching by controlling the instantaneous polarization state of the excitation light. Moreover, this variation process is directly mapped on the nano-femto scale by time-resolved two-color photoemission electron microscopy. The results are well reproduced by the finite-difference time-domain (FDTD) method. The current study of ultrafast control and spatiotemporally imaging the switching process establishes an experimental paradigm for revealing the complex mechanisms in ultrafast control of nondiffracting SPP and are useful for developing high-speed, highly-integrated nanophotonic devices, and on-chip circuits.

The meticulous task of soil region classification is fundamental to the effective management of soil resources and the development of accurate soil classification systems. These systems are crucial for the targeted restoration, safeguarding, and enhancement of land resources. In this research, we introduce an innovative soil classification model that combines the Joint Skewness (JS) algorithm, which is grounded in tensor theory, with a Back-Propagation Neural Network (BPNN). This combination is utilized for the rapid categorization of soil samples in specified areas, making use of spectral data from Laser-Induced Breakdown Spectroscopy (LIBS). The process begins with the application of JS to identify key variables, followed by the optimization of the JS-BPNN model's structure. The effectiveness of the model is then evaluated using metrics such as the confusion matrix, Kappa coefficient, and precision, which all highlight the model's reliability. Our experimental results validate the use of JS in filtering LIBS spectral features, effectively minimizing unnecessary data while preserving the spectral data's intrinsic physical characteristics. This leads to a significant enhancement in the model's analytical capabilities. The JS-BPNN model has demonstrated remarkable classification accuracy, achieving a peak accuracy of 99.8% on the test dataset. To further validate the JS approach for reducing data dimensionality and emphasize the superiority of the JS-BPNN model, we conducted a comparative analysis with other algorithms, such as k-Nearest Neighbor (KNN), Random Forest (RF), and Support Vector Machine (SVM), for the classification and recognition of soil geographic regions. The results confirm that the JS algorithm is a potent method for reducing the dimensionality of LIBS spectral data, and for different classification models, there are different optimal characteristic variables, with the JS-BPNN model proving to be exceptionally effective in soil classification and recognition tasks. [ABSTRACT FROM AUTHOR]

Metal (such as Cr, Ti, etc.) adhesion layers, which are generally used to prevent nanostructures from falling off during electron beam lithography processes, will introduce interface damping, decrease the near-field enhancement, and shorten the dephasing time of localized surface plasmons (LSP). Maintaining metal adhesion layers while alleviating the induced interface damping in nanostructures is crucial for high-performance sensing, surface-enhanced Raman scattering elements, plasmon-based photocathodes, and plasmon-mediated catalysis. Here, we experimentally demonstrated that the mitigation of interface damping of metal adhesion layers can be achieved through the coupling between the bright and dark plasmonic modes of gold nanorods. We attribute the mitigation to stronger confinement across the plasmon energy, which effectively reduces the proportion of plasmon energy injected into the Cr adhesive layers. Compared to weak coupling, the non-radiative damping of plasmonic modes 1 and 2 is reduced by approximately 74% and 85%, respectively, under strong coupling conditions. The experimental results are supported by finite-difference time-domain simulations and are well explained by the calculated interaction potential for different gap sizes. This research will further benefit applications where low interface damping is required, such as the construction of low-threshold nanolasers and ultrasensitive sensing systems. [ABSTRACT FROM AUTHOR]

Objective: Magnetic resonance‐guided laser interstitial thermal therapy (MRgLITT) is a novel tool and a minimally invasive treatment to drug‐resistant epilepsy (DRE). The focus of this research was to evaluate the effectiveness and safety of the newly developed dual‐wavelength dual‐output MRgLITT system LaserRO within two probe trajectories in treating DRE patients. Methods: This is a retrospective analysis conducted at a single center, examining patients with DRE who received treatment with the LaserRO MRgLITT system. The system utilizes a sophisticated laser technology that can be configured as conventional single output for single wavelength or innovative dual outputs for dual wavelengths. The study involved a comprehensive review of patient information, encompassing demographics, seizure history, details related to the surgical parameters, and the subsequent clinical results. Primary outcome was post‐operation seizure outcome defined as Engel Scale Class at the end of follow‐up time. Results: This study included a total of eight DRE patients received MRgLITT surgery between August 2022 and October 2023. Out of these, there were four mesial temporal lobe epilepsy (MTLE), three focal cortical dysplasia (FCD), and one cavernous malformation (CM) patients. Within the two probe trajectories, seven patients had single wavelength (980 or 1064 nm) laser treatment and one patient had dual‐wavelength (980 and 1064 nm) laser treatment. The median age of the patients was 27 (22–31) years, with a median follow‐up period of 9.7 (8.4–12.1) months. The mean BMI was recorded at 20.24 ± 2.95 kg/m2, and epilepsy history was 13 ± 6 years. The median intraoperative blood loss was 5 (5–9) mL, operation time was 231 (169–254) minutes, and length of stay (LOS) was 3 (3–5) days. The mean ablation volume ratio was 96.52% ± 3.67%. In terms of outcomes, over a median follow‐up time of 9.7 (range 8.4–12.1) months, there were two patients got Engel I, five patients got seizure‐free, and one patient decreased 75% seizure. Importantly, no serious complications following the procedures occurred. Conclusions: The preliminary results indicate that the MRgLITT procedure, which operates dual‐output laser with single or dual wavelengths (980/1064 nm) within the two trajectories, is both effective and safe as a minimally invasive approach for different types of DRE patients. [ABSTRACT FROM AUTHOR]

The formation and evolution of laser-induced periodic structures (LIPSS) have attracted much attention due to their broad applications and rich physics. The literature has shown that excessive laser energy accumulation, such as increasing single pulse energy or cumulative pulse number on a sample, leads to a final fuzzy LIPSS period or even disappearance of the period. This article discovers a new phenomenon by increasing the laser fluence; the periodic structure appears blurred and disappears in the middle of the laser fluence region. Two contrary evolution tendencies of the period’s disappearance are observed for the first time. This phenomenon can be attributed to femtosecond ablation regimes in different fluence regions. The experimental results and discussion provide a powerful guarantee for the high-quality preparation of structures by controlling the experimental parameters for future practical applications. The findings of this study play a significant role in regulating the LIPSS period and provide ideas for avoiding the hidden danger of the cycle structure disappearing during the creation of the LIPSS structure, which has practical implications for future LIPSS applications.