Applied Physics B最新文献

A nanostructured metamaterial absorber composed of alternating semiconductor and dielectric layers is presented and numerically analyzed in this article. The development of a semiconductor adjustable absorber in the THz will open up new possibilities for quantum information science, imaging, health, and sensing applications, particularly those that need to be portable. Here, we build a unique semiconductor nanostructured metamaterial that exhibits increased absorption efficiency at various temperatures by carefully organizing and shaping the nanostructured semiconductor metamaterial geometry. The stability of absorption properties is observed for a large range of the alternating layers width values. This discovery paves the way for the potential development of a new generation of THz quantum detectors that operate close to room temperature and offer exceptional improved absorption for a broader variety of applications.

Dynamic programmable metasurface (PMS) with multifunctionality has attracted attention due to its flexible abilities in manipulating terahertz (THz) beams. However, real-time control of full-space THz beams by metasurfaces still faces several technical challenges. In this study, we present a multi-bit liquid-crystal (LC) -integrated PMS that enables multifunctional manipulation of full-space THz beams. The proposed PMS is characterized by an achievable 3-bit working state and a near 315° maximum phase shift can be achieved in the range of 0.4–0.44 THz (transmission mode) and 0.7–0.72 THz (reflection mode). Metasurfaces can manipulate the transmissive and reflective beams by dynamically switching array encoding, allowing for multifunctional manipulation of full-space THz beams. To better demonstrate the advantages of multifunctional integration of the device, various functions are realized by dynamically manipulating the coding pattern of the PMS, including beam steering, orbital angular momentum (OAM), and holography. This work is expected to advance the application of PMS in full-space THz beam manipulation devices.

In this article, we present our analysis of the Raman-induced wavelength shift (RIWS) in configuring high-performance temperature sensor by employing a highly nonlinear Chalcogenide (As₃₀S₇₀) microstructured optical fiber (MOF) having central holes partially filled with Chloroform (CHCl₃). Through precise adjustment of the device parameters, we demonstrate a sensitivity of temperature measurement of ~ 2.6262 nm/^°C in the mid-infrared (MIR) wavelength range. Implementing Artificial Neural Network (ANN) analysis, this sensitivity increases to 2.7039 nm/^°C yielding a temperature resolution of 0.24688 ^°C. To our knowledge, this is the first investigation that specifically addresses RIWS effect in temperature sensing using Chalcogenide fiber at MIR range.

Laser drilling of glass using tightly focused femtosecond laser pulses while monitoring laser-generated sound is demonstrated, aiming laser drilling controlled by laser-generated sound. The amount of laser ablation was found to have a monotonical relation to the intensity of the sound pressure. It was also found that when the laser pulses were focused on the glass surface, the sound pressure increased in the initial stage of the laser drilling and then declined as the hole became deeper. These behaviors were the result of increasing ablation caused by surface roughening and loss of sound propagation through the hole, respectively. It was further found that the movement of the objective lens (OL) toward the target material at an appropriate constant speed created a hole with a large depth and narrow entrance (a high aspect ratio); that is, the lens movement changed the performance of the laser drilling. A simple method for moving the lens using laser-generated sound was adopted in this study. The axial position of the OL was controlled by maximizing the sound pressure at each pulse irradiation to obtain a hole with a high aspect ratio, which was the same as the maximum hole depth obtained by the iterative experiments in the constant-speed control of the OL. More sophisticated control methods should be developed according to the given applications.

Quantum dense coding enables the transmission of two bits of classical information using a single qubit, leveraging the initial maximal entanglement of a Bell state channel. This study investigates this process within a two-qubit anisotropic XY Heisenberg spin chain, influenced by Herring-Flicker coupling and subjected to an external magnetic field. In practical scenarios, the interaction between spins, characterized by the variable coupling strength J, significantly impacts the assessment of these spin systems for quantum computing and communication. Therefore, it is essential to consider the distance between the spins. This article aims to analyze the effects of temperature variations on the quantum communication channel, taking into account Herring-Flicker coupling, which is vital for implementing quantum communication protocols in real-world applications. Our findings suggest that the current channel shows promising potential for the quantum-dense coding protocol.

The shear wavefront propagates in a single direction, influenced by the phase deviation of the missing orthogonal direction in the interference pattern. Furthermore, the restriction of phase sampling points in the shear direction has a certain impact on attaining high spatial resolution in wavefront reconstruction. To attain high-precision wavefront reconstruction, it is necessary to acquire additional sampled data from various orthogonal shear directions. During our investigation, a wavefront reconstruction method was proposed for multi-directional orthogonal lateral shearing interferometry. This method establishes a relationship model that corresponds to multi-directional differential wavefront and differential Zernike polynomials. Using the principle of wavefront reconstruction with differential Zernike polynomials, it allows for the reconstruction of wavefronts from any orthogonal-direction lateral shearing interference patterns. To validate the efficacy of the proposed method, the wavefront reconstruction accuracy of various sets of arbitrarily oriented shearing interferograms was simulated and analyzed. Additionally, the results were compared to those obtained from the average differential wavefront of multiple orthogonal shearing interferograms. The results show that by choosing multiple orthogonal shear directions to improve phase sampling data, wavefront reconstruction can be successfully accomplished using any number of orthogonal lateral shearing interferograms. This effectively reduces the impact of both random and systematic errors on the spatial resolution of the wavefront during the reconstruction process. Ultimately, the accuracy of the proposed method was confirmed through experimental validation. After comparing the repeatability measurement with the results obtained from the ZYGO interferometer, it was discovered that the precision of the relative measurement error in RMS was superior to 0.01λ.

Rapid and real-time monitoring of the concentrations of metal elements in water is essential for water quality evaluation and freshwater production through water desalination. Here we show the ability of the deep reinforcement learning (DRL) in assisting the filament-induced breakdown spectroscopy (FIBS) technique for high-sensitivity and standoff detection of trace-level metal elements in water. The DRL agent is trained to determine two important intricately-coupled parameters, the pulse duration and the distance between the filament starting point and the water surface, achieving the optimal control of the FIBS intensity at the air–water interface. The limits of detection of DRL-assisted FIBS for Al, Cu and Pb elements in water reach to 230, 850 and 1120 ppb, respectively. With this method, we further perform high-sensitivity analysis of the diffusion properties of multi-salt species during the freezing desalination, and find that the captured possibility of metal ions into the ice body decreases with the increasing freezing time, which exhibits a strong dependence on the metal species. This work opens up possibilities in controlling the nonlinear optical emissions by the high-intensity filament excitation assisted by the cutting-edge artificial intelligence technologies.

An analytical study of wave theory-based multilayered SPR-based fiber optic biosensor by shinning Bessel-Gauss (BG) beam is proposed here for early diagnosis of dengue infection. At first, this wave theory-based analytical model shined by Gaussian (G) beam is validated with the already reported experimental data, where the obtained results are in good accord with the experimental findings presented by Y. M. Kamil et al. in 2018. So, it affords the experimental confirmation of the validity of the proposed theory. The enhancement in sensitivity is 1.99 times ascertained by employing G beam for our proposed structure at a spectral sensitivity of 10.008 nm/nM. This theoretical investigation has then been extended utilizing the BG beam, where the observed sensitivity is increased to 59,602.00 dB/RIU and 20.016 nm/nM with a resolution of 1.68 × 10^–7, which is 3.98 times higher than the referred published work. Here, the limit of detection is 0.06 pM with a minimum change in transmitted output power of 0.8658 milliwatt/RIU. When the DENV-II E protein concentration ranges from 0.08 pM to 0.6 nM, higher spectral shifts are observed. Consequently, enhancements in sensitivity and resolution can be achieved at reduced concentrations, paving the idea of diagnosis of dengue infection at an early stage.

Pulsed laser ablation is an increasingly prevalent method for fast ion trap loading of various species, however characteristics of the ablation target source material can affect the ion-loading process. One factor which can reduce the atomic flux from a target is oxidation during atmospheric exposure when preparing or making changes to the ion trap vacuum system. Recent work has shown that perovskite ablation targets produce consistent atomic densities even after exposure to atmosphere when compared to elemental source targets. In this work, we directly compare calcium (Ca) and calcium-titanate (CaTiO(_3)) ablation targets, characterizing the neutral atomic beam flux using resonant, time-resolved absorption spectroscopy of the 423 nm ¹S₀ (rightarrow) ¹P₁ transition in neutral Ca. We measure the ablation plume longitudinal and transverse temperatures, number density, ion production, and spot lifetime for each target. In addition, we compare the probe laser beam absorption for both targets before and after 21-h of exposure to atmosphere, demonstrating the relative robustness of the CaTiO(_3) source.

Interfering radiation, such as self-emitting thermal radiation, infrared radiation from heating sources, and combustion gas radiation, significantly impacts the use of optical thermometry. How to improve the precision of temperature measurement in such an environment is a key issue. Therefore, this work aimed to quantitatively analyze the temperature measurement precision of luminescence lifetime thermometry for measuring the temperatures of hot components in environments with interfering radiation. In this paper, based on the quantitative analysis of measurement noise of optical signal and the error propagation theory, we proposed a theoretical model for predicting the temperature measurement precision of luminescence lifetime thermometry. Using blue LED as the interfering radiation source, the temperature measurement experiments of high-temperature surfaces under different interfering radiation intensities were carried out. By comparing the measured precision based on the standard deviation of repeated experiments with the predicted precision of the theoretical model proposed in this paper, the reliability of this theoretical model was verified. The experiments also revealed that the temperature measurement precision was linearly related to the square root of the measured signal intensity (i.e., the sum of luminescence signal and interfering radiation signal). With the increase of the background interfering radiation intensity, although the accuracy of temperature measurement did not change significantly, the measurement noise increases, resulting in a significant increase in random error of measured temperature. This work provides guidance for developing luminescence lifetime thermometers and their applications in environments with interfering radiation.