Intense Laser Light Research Articles

Photonic Synapse of CrSBr/PtS2 Transistor for Neuromorphic Computing and Light Decoding

Abstract Field effect transistors based on 2D layered material have gained significant potential in emerging technologies, such as neuromorphic computing and ultrafast memory response for artificial intelligence applications. This study proposes a facile approach to fabricate an optoelectronic artificial synapse for neuromorphic computing and light‐decoding information system by utilizing the 2D heterostructure of CrSBr/PtS2 to overcome circuit complexity. The CrSBr layer serves as a trapping layer, while PtS2, mounted on top of CrSBr, acts as a channel layer. PtS2 exhibits n‐type semiconductor behavior with a hysteresis that varies with the thickness of the underlying CrSBr layer. The heterostructure device, featuring a 96.3 nm thick CrSBr layer, exhibited a large memory window of 11.9 V when the gate voltage is swept from −10 V to +10 V. Various synaptic behaviors are effectively demonstrated, including paired‐pulse facilitation, excitatory postsynaptic current, optical spike number and intensity‐dependent plasticity using laser light at a wavelength of 365 nm. The device achieves 26 distinct output signals depending on the intensity of the incident laser light, ranging from 10 to 385 mW cm−2, enabling its applications for light‐decoded information security systems. Thus, the investigation presents a unique approach to artificial intelligence and cybersecurity systems.

Laser Aggregometry Assessment of Blood Microrheology in a Slit Fluidic Channel Covered With Endothelial Cells.

The blood rheology in vitro in glass or plastic microfluidic chips is different from that in vivo in blood vessels with similar geometry. Absence of vascular endothelium is suggested to cause these discrepancies. This work aims to perform in vitro measurements of blood microrheologic parameters in a slit microfluidic channel covered with endothelial cells (HUVEC). The laser aggregometry was employed to measure the intensity of laser light, backscattered from the blood flow, as a function of shear stress to evaluate the hydrodynamic strength of red blood cells (RBC) aggregates in terms of critical shear stress (CSS). The results demonstrated a decrease in CSS accompanied by an increase in the accuracy of its measurement at similar shear stresses when endothelial cells were present in the channel. The findings hold valuable implications for advanced approaches for endothelization of microfluidic devices, facilitating the study of blood flow dynamics in physiologically more relevant environment.

Calibration-free heterodyne phase-sensitive dispersion spectroscopy: quantitative gas sensing and recovery of absorption spectra.

Heterodyne phase-sensitive dispersion spectroscopy (HPSDS) is a quantitative non-intrusive gas sensing technique based on the determination of the refractive index of the target gas in the vicinity of an absorption transition. Since the phase instead of the intensity of the probing laser light is targeted, the technique boasts the advantage of being normalization-free. It is thus largely immune to laser intensity fluctuations due to either system instability or ambient interferences. Previous HPSDS-based sensors typically require calibration using standard mixtures to establish a look-up table between the measured phase signal and gas concentrations, which is both cumbersome and problematic when there are significant compositional variations between the calibration standards and the target gas. In this work, we present a robust and generic technique that addresses this issue with a successful realization of fully calibration-free measurements. Spectral-fitting to the entire dispersion spectra with free variables related to transition linecenter, broadening width, and integrated absorbance were used to eliminate the effects of unknown spectral broadening coefficients. What we believe to be a novel analytical model was proposed to unify both direct injection-current dithering-based HPSDS that includes simultaneous frequency/intensity modulation, and the external electro-optic modulator (EOM) modulation-based HPSDS with a non-ideal linear response of EOM. The proposed technique was first validated via numerical experiment to determine the gas concentration and the recovery of the absorption profiles. Actual experiments were subsequently performed for the measurement of CH4 near 1.65 µm, N2O near 4.46 µm, and NO near 5.26 µm, collectively demonstrating the capability of the technique for both near- and mid-infrared lasers with diverse modulation characteristics. Further demonstrations were performed to measure NH3 concentrations at elevated temperatures through the fitting of the multiple dispersion spectra near 9.06 µm. The robust iterative spectral-fitting strategy and the measurement accuracies confirm the robustness of the proposed calibration-free (CF) HPSDS technique for quantitative gas sensing.

Functional light diffusers based on hybrid CsPbBr3/SiO2 aero-framework structures for laser light illumination and conversion

The new generation of laser-based solid-state lighting (SSL) white light sources requires new material systems capable of withstanding, diffusing, and converting high intensity laser light. State-of-the-art systems use a blue light emitting diode or laser diode in combination with color conversion materials, such as yellow emitting Ce-doped phosphors or red and green emitting quantum dots (QD), to produce white light. However, for laser-based high-brightness illumination thermal management and uniform light diffusion are still major challenges in the quest to convert a highly focused laser beam into an efficient lighting solution. Here, we present a material system consisting of a highly open porous (> 99%) framework structure of hollow SiO2 microtubes. This framework structure enables efficient and uniform light distribution as well as ensuring good thermal management even at high laser powers of up to 5 W, while drastically reducing the speckle contrast. By further functionalizing the microtubes with halide perovskite QDs (SiO2@CsPbBr3 as model system) color conversion from UV to visible light is achieved. By depositing an ultrathin (~ 5.5 nm) film of poly(ethylene glycol dimethyl acrylate) (pEGDMA) via initiated chemical vapor deposition (iCVD), the luminescent stability of the QDs against moisture is enhanced. The demonstrated hybrid material system paves the way for the design of advanced and functional laser light diffusers and converters that can meet the challenges associated with laser-based SSL applications.Graphical

Multi-physics field coupling analysis of in-situ laser-assisted micro-imprinting of micro tapered holes

Micro tapered holes find extensive use in various domains including detection, infusion, lighting, etc. This study has investigated the deformation behavior and machining quality of micro-tapered holes generated by in-situ laser-assisted micro-imprinting (In-LAI) using a diamond indenter. The effects of in-situ laser-assisted action on the edge bulge at the inlet, residual stress at the outlet, and microcracks at outlet of a micro tapered hole have been analyzed by using a coupled optical-thermal-force multiphysics field model. Replacing conventional Gaussian heat sources with laser light intensity distributions obtained from optical-thermal coupling model analysis. Compared to ambient temperature, Laser intensity at the tip of the diamond indenter under operating conditions decreased by 11.59 %. The in-situ laser-assisted action has reduced the force by 13 %, reduced the edge bulge at the inlet of the micro tapered hole by 57.3 %, increased the residual compressive stress at the outlet by 47.6 %, and suppressed the generation of microcracks at the outlet. The results show that In-LAI is an effective technique for micro-tapered hole machining, and the multi-physical field coupling research method also provides implications for other in-situ laser-assisted machining (In-LAM) techniques.

Effect of light-assisted tunable interaction on the position response function of cold atoms.

The position response of a particle subjected to a perturbation is of general interest in physics. We study the modification of the position response function of an ensemble of cold atoms in a magneto-optical trap (MOT) in the presence of tunable light-assisted interactions. We subject the cold atoms to an intense laser light tuned near the photoassociation (PA) resonance and observe the position response of the atoms subjected to a sudden displacement. Surprisingly, we observe that the entire cold atomic cloud undergoes collective oscillations. We use a generalized quantum Langevin approach to theoretically analyze the results of the experiments and find good agreement.

Flexible visible and near-infrared laser detector based on bismuth sulphide nanorods

The development of a flexible, visible and near-infrared laser detector with fast response holds significant potential for applications in wearable electronics, binary switches, and other fields. In this study, we utilized a flexible transparent polyimide (PI) substrate known for its exceptional thermal resistance up to 400 °C to fabricate an innovative type of flexible laser detector. Systematic investigations demonstrate that the bismuth sulphide nanorods-based laser detector exhibits not only high flexibility and light-weight properties but also excellent linear current characteristics and strong photosensitive dependence on laser light intensity. This research presents a novel approach for the fabrication of high-performance flexible optoelectronic devices.

Boosting the in-vitro effectiveness of photodynamic therapy on MCF-7 breast cancer cells with encapsulated malachite green by silica nanoparticles

Photodynamic therapy (PDT) is a promising cancer treatment strategy utilizing photosensitizers (PS) and light to generate singlet oxygen, with Malachite Green (MG) showing high singlet oxygen quantum yield. Effective delivery of MG to the target tissue remains a key challenge. Encapsulation techniques have been investigated to improve PS delivery, minimize PS leakage, inhibit diaphorase-induced reduction, and mitigate PS-related toxicity. Silica nanoparticles (SiNPs) offer favorable characteristics for drug delivery in PDT and serve as promising delivery carriers. In this study, SiNPs were synthesized and employed as carriers for MG. The size and shape of nanoparticles were determined using Transmission Electron Microscopy (TEM). A range of concentrations of MG were applied to MCF-7 breast cancer cells in order to evaluate the cytotoxicity of both naked and encapsulated MG. This helped identify the most effective concentrations and exposure durations required to induce damage under red laser light (Intensity ∼110 mW/cm2). The results indicated that SiNPs-encapsulated MG exhibited superior efficacy compared to naked MG, with a concentration efficacy increase of +50 % and an exposure time efficacy increase of +45 %. This underlines the enhanced capability of encapsulated MG to eliminate MCF-7 cells when compared to naked MG. The application of synthesized SiNPs for MG delivery improved the effectiveness of photodynamic therapy by augmenting MG bioavailability in target cells.

Explicit and approximate series solutions for nonlinear fractional wave-like differential equations with variable coefficients

This work investigates the exact and accurate approximate series solutions of the strongly nonlinear wave-like differential equations of fractional order with variable coefficients utilizing the Laplace residual power series technique in the 2D, and 3D-space. The posed model is a notable model in mathematical physics, engineering physics, and biophysics, to characterize the variations in laser light intensity, and fluid particle velocity distributions in turbulent flows. In the meaning of Caputo fractional derivative, the posed models are solved analytically via simulation of the generalized Taylor formula in the Laplace space. Different from the other analytic methods, an easy recurrence formula for finding the Laplace power series coefficients is derived. To validate the proposed approach, it is applied to three interesting problems. The approximate analytical solutions of studied fractional problems are expressed in fast-converging Caputo-fractional Maclaurin formulas. The results are numerically and graphically analyzed to demonstrate the efficiency and applicability of the technique, as well as to examine the effects of partial arrangement on the behavior of the solutions. Ultimately, the results and numerical simulations indicate that the used technique is an effective approach and accurate tool for solving fractional evolution models and other fractional models arising in nonlinear phenomena.

Generation of entangled waveguided photon pairs by free electrons.

Entangled photons are a key resource in quantum technologies. While intense laser light propagating in nonlinear crystals is conventionally used to generate entangled photons, such schemes have low efficiency due to the weak nonlinear response of known materials and losses associated with in/out photon coupling. Here, we show how to generate entangled polariton pairs directly within optical waveguides using free electrons. The measured energy loss of undeflected electrons heralds the production of counter-propagating polariton pairs entangled in energy and emission direction. For illustration, we study the excitation of plasmon polaritons in metal strip waveguides that strongly enhance light-matter interactions, rendering two-plasmon generation dominant over single-plasmon excitation. We demonstrate that electron energy losses detected within optimal frequency ranges can reliably signal the generation of plasmon pairs entangled in energy and momentum. Our proposed scheme is directly applicable to other types of optical waveguides for in situ generation of entangled photon pairs.

Time-dependent Gutzwiller simulation of Floquet topological superconductivity

Periodically driven systems provide a novel route to control the topology of quantum materials. In particular, Floquet theory allows an effective band description of periodically-driven systems through the Floquet Hamiltonian. Here, we study the time evolution of d-wave superconductors irradiated with intense circularly-polarized laser light. We consider the Floquet t–J model with time-periodic interactions, and investigate its mean-field dynamics by formulating the time-dependent Gutzwiller approximation. We observe the development of the idxy-wave pairing amplitude along with the original dx2−y2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${d}_{{x}^{2}-{y}^{2}}$$\\end{document}-wave order upon gradual increasing of the field amplitude. We further numerically construct the Floquet Hamiltonian for the steady state, with which we identify the system as the fully-gapped d + id superconducting phase with a nonzero Chern number. We explore the low-frequency regime where the perturbative approaches in the previous studies break down, and find that the topological gap of an experimentally-accessible size can be achieved at much lower laser intensities.

Enhancing photodynamic therapy efficacy through silica nanoparticle-mediated delivery of temoporfin for targeted in vitro breast cancer treatment

Photodynamic therapy (PDT), an approach to cancer treatment, relies fundamentally on two key elements: a light source and a photosensitizing agent. A primary challenge in PDT is the efficient delivery of photosensitizers to the target tissue, hindered by the bodyʼs reticuloendothelial system (RES). Silica nanoparticles (SiNPs), known for their unique properties, emerge as ideal carriers in this context. In this study, SiNPs are utilized to encapsulate Temoporfin, a photosensitizer, aiming to enhance its delivery and reduce toxicity, particularly for treating MCF-7 cancer cells in vitro. The synthesized SiNPs were meticulously characterized by their size and shape using Transmission Electron Microscopy (TEM). The study also involved evaluating the cytotoxicity of both encapsulated and naked Temoporfin across various concentrations. The objective was to determine the ideal concentration and exposure duration using red laser light (intensity approximately 110 mW/cm2) to effectively eradicate MCF-7 cells. The findings revealed that Temoporfin, when encapsulated in SiNPs, demonstrated significantly greater effectiveness compared to its naked form, with notable improvements in concentration efficiency (50 %) and exposure time efficiency (76.6 %). This research not only confirms the superior effectiveness of encapsulated Temoporfin in eliminating cancer cells but also highlights the potential of SiNPs as an efficient drug delivery system in photodynamic therapy. This sets the groundwork for more advanced strategies in cancer treatment.

A new mixed-ligand zinc(II) complex of 3-hydroxy and 4-chloro substituted pyridine-2-carboxylic acid: Synthesis, characterization, NLO properties and DFT calculation

Molecular engineering of metal-organic frameworks has recently attracted increasing attention due to their potential technological applications in the fields of optics and photonics. In addition to improved optical properties, the incorporation of metal ions into organic ligands makes it possible to control the intensity and polarization of the incident laser light. This makes organometallic complexes valuable and suitable candidates for nonlinear optical applications. In this study, a novel Zn(II) complex was synthesized by using 4-chloropyridine-2-carboxylic acid (4-Clpca) and 3-hydroxypyridine-2-carboxylic acid (3OHpca). The structural and spectroscopic properties of the Zn(II) complex were examined through XRD, FT-IR and UV-Vis techniques. The HOMO-LUMO energy range for the Zn(II) complex was found to be 4.7358 eV. Nonlinear optical parameters of Zn(II) complex were investigated as static and frequency-dependent (ω = 0.0856453887 au) methods. The dc-Kerr effect γ(-ω;ω,0,0) and EFSHG γ(−2ω;ω,ω,0) parameters were calculated as 13.04 × 10−36 esu and 2258.9 × 10−36 esu, respectively. The newly synthesized Zn(II) complex, which has weak second-order NLO properties due to the fully occupied electronic configuration of the Zn(II) ion, is quite promising in terms of its third-order optical properties.

Strong light-matter interaction and non-linear effects in organic semiconducting CuPc nanotubes: realization of all-optical diode and switching applications.

Spatial self-phase modulation based on the optical Kerr effect has gained momentum in recent years to analyse the nonlinear optical properties of 2D inorganic nanomaterials. In the present work, we investigate the strong light-matter interaction of organic semiconducting materials based on SSPM, by developing Cu-phthalocyanine (CuPc) nanotubes via a solvothermal technique. The low bandgap of CuPc facilitates the study of its nonlinear optical properties for a broad spectrum range from 671 nm to 405 nm. Intense laser light passing through the CuPc dispersion produces concentric diffraction ring patterns at the far field from which high n2 and χ(3) values, 3.667 × 10-5 cm2 W-1 and 2 × 10-3 esu, respectively, are obtained for the 405 nm laser. This strong nonlinear optical response of CuPc has been utilized to realize non-reciprocal light propagation by constructing a CuPc/SnS2 hybrid structure, which makes an effective all-optical photonic diode. In addition, the all-optical switching is presented using CuPc nanotubes based on the spatial cross-phase modulation technique. In this technique a phase change is induced in the weak signal beam modulated by the strong controlling light beam, which helps to produce all-optical logic gates and all-optical switching devices. The experimental findings of this work unravel the potentially powerful applications of CuPc nanotubes in all-optical information transmission and all-optical photonic devices.

Geometry effects on energy selective focusing of laser-driven protons with open and closed hemisphere-cone targets

Relativistically intense laser light interacting with solid density targets can accelerate protons to multi-MeV energies via the target normal sheath acceleration process. The use of hollow hemisphere targets with a hollow conical region to focus protons of selected energies, for applications such as isochoric heating of matter and for the fast ignition approach to inertial confinement fusion, is explored for laser intensity Wcm−2. Specifically, the effects of having the cone tip open or closed is investigated experimentally and via a programme of scaled particle-in-cell simulations. The open cone configuration is found to result in proton focusing in the energy range of 9 to 24 MeV, and produce an annular profile for higher energy components, up to 55 MeV, while the spatial distribution of lower energy components remains unchanged. By contrast, for the closed cone case, the focusing effect is diminished by the fields present on the inner wall of the cone tip. Simulations reveal that strong electrostatic and magnetic fields present on the inner surfaces of the target induce the focusing effect with the open cone, but also result in proton divergence in the case of the closed cone. Additionally, the simulations demonstrate the possibility to tailor the cone geometry to select the energy range over which the focusing occurs.

Proton acceleration with intense twisted laser light

Proton acceleration with intense twisted laser light

Narrowband photoblinking InP/ZnSe/ZnS quantum dots for super-resolution multifocal structured illumination microscopy enhanced by optical fluctuation.

Cadmium-free quantum-dot (QD) fluorophores can bridge the gap between the macroscopic and microscopic domains in fluorescence super-resolution bioimaging. InP/ZnSe/ZnS QD photoblinking fluorescent probes can improve the performance of reactive super-resolution imaging techniques and spontaneously switch fluorophores between at least two states (open and close) without depending on intense laser light and specialized buffers for bioimaging. Multifocal structured illumination microscopy (MSIM) provides a two-fold resolution enhancement in sub-diffraction imaging, but higher resolutions are limited by the pattern frequency and signal-to-noise ratio. We exploit the synergy between MSIM and spontaneously switching InP/ZnSe/ZnS QD fluorophores to further increase the imaging resolution. We demonstrate the experimental combination of optical-fluctuation-enhanced super-resolution MSIM using ultrasonic-oscillation-assisted organic solvothermal synthesis of narrowband photoblinking InP/ZnSe/ZnS QDs. The InP/ZnSe/ZnS QDs show a monodisperse grain size of approximately 9nm, fluorescence quantum yields close to 100%, and full width at half maximum below 30nm. The structural, electronic, and optical properties are characterized through experiments and first-principles calculations. The enhanced MSIM imaging achieves an approximate fourfold improvement in resolution for fixed cells compared with widefield imaging. The proposed InP/ZnSe/ZnS QD fluorescent probes seem promising for super-resolution imaging using MSIM.

Nonlinear branched flow of intense laser light in randomly uneven media

Branched flow is an interesting phenomenon that can occur in diverse systems. It is usually linear in the sense that the flow does not alter the properties of the medium. Branched flow of light on thin films has recently been discovered. It is therefore of interest to know whether nonlinear light branching can also occur. Here, using particle-in-cell simulations, we find that in the case of an intense laser propagating through a randomly uneven medium, cascading local photoionization by the incident laser, together with the response of freed electrons in the strong laser fields, triggers space–time-dependent optical unevenness. The resulting branching pattern depends dramatically on the laser intensity. That is, the branching here is distinct from the existing linear ones. The observed branching properties agree well with theoretical analyses based on the Helmholtz equation. Nonlinear branched propagation of intense lasers potentially opens up a new area for laser–matter interaction and may be relevant to other branching phenomena of a nonlinear nature.

Simultaneous Detection of Gas Concentration and Light Intensity Based on Dual-Quartz-Enhanced Photoacoustic-Photothermal Spectroscopy

This research proposes a method for the simultaneous acquisition of the second harmonic (2f) signal of quartz-enhanced photoacoustic spectroscopy (QEPAS) and the first harmonic (1f) signal of quartz-enhanced photothermal spectroscopy (QEPTS) based on the dual-quartz-enhanced photoacoustic–photothermal spectroscopy. The laser beam is first wavelength-modulated by the injection current and then intensity-modulated by an acoustic-optic modulator. The frequency of the wavelength modulation is half of the QTF1 resonant frequency, and the frequency of the intensity modulation is equal to the QTF2 resonant frequency. A modulated laser beam traveled through the two arms of the QTF1 and converged on the root of the QTF2. The 2f photoacoustic and 1f photothermal signals are concurrently obtained using the frequency division multiplexing technology and lock-in amplifiers, which allows the simultaneous detection of the gas concentration and laser light intensity. CH4 is chosen as the target gas, and the variations of the 2f photoacoustic and 1f photothermal signals are evaluated at various gas concentrations and light intensities. According to the experiments, the amplitude of the 1f photothermal signal has a good linear connection with light intensity (R2 = 0.998), which can be utilized to accurately revise the 2f photoacoustic signal while light intensity fluctuates. Over a wide range of concentrations, the normalized 2f photoacoustic signals exhibit an excellent linear response (R2 = 0.996). According to the Allan deviation analysis, the minimum detection limit for CH4 is 0.39 ppm when the integration time is 430 s. Compared with the light intensity correction using a photodetector for the QEPAS system, this approach offers a novel and effective light intensity correction method for concentration measurements employing 2f analysis. It also has the advantages of low cost and compact volume, especially for mid-infrared and terahertz systems.

Intense and Superflat White Laser with 700-nm 3-dB Bandwidth and 1-mJ Pulse Energy Enabling Single-Shot Subpicosecond Pulse Laser Spectroscopy.

An optical spectrometer is a basic spectral instrument that probes microscopic physical and chemical properties of macroscopic objects but generally suffers from difficulty in broadband time-resolved measurement. In this work, we report the creation of ultrabroadband white-light laser with a 3-dB bandwidth covering 385 to 1,080 nm, pulse energy of 1.07 mJ, and pulse duration of several hundred femtoseconds by passing 3-mJ pulse energy, 50-fs pulse duration Ti:Sapphire pulse laser through a cascaded fused silica plate and chirped periodically poled lithium niobate crystal. We utilize this unprecedented superflat, ultrabroadband, and intense femtosecond laser light source to build a single-shot (i.e., single-pulse) subpicosecond pulse laser ultraviolet-visible-near-infrared spectrometer and successfully measure various atomic and molecular absorption spectra. The single-shot ultrafast spectrometer may open up a frontier to monitor simultaneously the ultrafast dynamics of multiple physical and chemical processes in various microscopic systems.