Transmission Characteristic Simulation of High Frequency Acousto-Optic Modulators

The way by which one can make sure the operating mode of the modulation is by observing the Comsol results of the designed model of proposed acousto-optic modulator (AOM). These results include the pressure distribution, sound pressure distribution, stress distribution at piezoelectric, far-field analysis that describes the diffracted light orders, and electric potential versus light frequency. Throughout the simulating process of modulator operating using Comsol, it begins when the RF is power by a voltage of 100 V, the light is then split into first ordered diffraction, which implies that the modulator is in the operating mode. The use of semiconductor materials is due to its smaller gap that easily transfers the energy that leads to generating first order diffraction when they provided a voltage power. It mentioned that zero order diffraction indicates the modulator does not run;other orders are appearing with increasing the frequency of light leading to decrease of the efficiency of the modulator performance.

Serrated periodic electrode for high energy efficiency and large bandwidth acousto-optic modulators

In an acousto-optic modulator,the electrode shape plays an important role in performance,since it affects the distribution of the acoustic field.The acousto-optic modulator based on the conventional rectangular electrode has the problems of low energy efficiency and small modulation bandwidth due to an imperfect acoustic field.In this paper,a new serrated periodic electrode has been proposed for using acousto-optic modulator transducers.The proposed electrode has the following advantages.By using serrated periodic electrodes to suppress the sidelobes,the collimation of the acoustic field in the direction perpendicular to the light incidence is improved.This makes the acousto-optic modulator have a stable diffraction efficiency fluctuation and high energy efficiency.In addition,the electrode has a large divergence angle in the direction of light incidence,so a large bandwidth can be obtained.The simulations and experiments demonstrate that the serrated periodic electrode has an increased bandwidth and high energy efficiency.

Optical image processing using acousto-optic modulators as programmable volume holograms: a review [Invited]

Bragg processing using a volume hologram offers an alternative in optical image processing in contrast to Fourier-plane processing. By placing a volume hologram near the object in an optical imaging setup, we achieve Bragg processing. In this review, we discuss various image processing methods achievable with acousto-optic modulators as dynamic and programmable volume holograms. In particular, we concentrate on the discussion of various differentiation operations leading to edge extraction capabilities.

Acousto-optic scanning spatial-switching multiphoton lithography

Nano-3D printing has obtained widespread attention owing to its capacity to manufacture end-use components with nano-scale features in recent years.Multiphoton lithography(MPL)is one of the most promising 3D nanomanufacturing technologies,which has been widely used in manufacturing micro-optics,photonic crystals,microfluidics,meta-surface,and mechanical metamaterials.Despite of tremendous potential of MPL in laboratorial and industrial applications,simultaneous achievement of high throughput,high accuracy,high design freedom,and a broad range of material structuring capabilities remains a long-pending challenge.To address the issue,we propose an acousto-optic scanning with spatial-switching multispots(AOSS)method.Inertia-free acousto-optic scanning and nonlinear swept techniques have been developed for achieving ultrahigh-speed and aberration-free scanning.Moreover,a spatial optical switch concept has been implemented to significantly boost the lithography throughput while maintaining high resolution and high design freedom.An eight-foci AOSS system has demonstrated a record-high 3D printing rate of 7.6×10^(7)voxel s^(-1),which is nearly one order of magnitude higher than earlier scanning MPL,exhibiting its promise for future scalable 3D nanomanufacturing.

A review of liquid crystal spatial light modulators:devices and applications

Spatial light modulators,as dynamic flat-panel optical devices,have witnessed rapid development over the past two decades,concomitant with the advancements in micro-and opto-electronic integration technology.In particular,liquid-crystal spatial light modulator(LC-SLM)technologies have been regarded as versatile tools for generating arbitrary optical fields and tailoring all degrees of freedom beyond just phase and amplitude.These devices have gained significant interest in the nascent field of structured light in space and time,facilitated by their ease of use and real-time light manipulation,fueling both fundamental research and practical applications.Here we provide an overview of the key working principles of LC-SLMs and review the significant progress made to date in their deployment for various applications,covering topics as diverse as beam shaping and steering,holography,optical trapping and tweezers,measurement,wavefront coding,optical vortex,and quantum optics.Finally,we conclude with an outlook on the potential opportunities and technical challenges in this rapidly developing field.

Unveiling the biological role of sphingosine-1-phosphate receptor modulators in inflammatory bowel diseases

Inflammatory bowel disease(IBD)is chronic inflammation of the gastrointestinal tract that has a high epidemiological prevalence worldwide.The increasing disease burden worldwide,lack of response to current biologic therapeutics,and treatment-related immunogenicity have led to major concerns regarding the clinical management of IBD patients and treatment efficacy.Understanding disease pathogenesis and disease-related molecular mechanisms is the most important goal in developing new and effective therapeutics.Sphingosine-1-phosphate(S1P)receptor(S1PR)modulators form a class of oral small molecule drugs currently in clinical development for IBD have shown promising effects on disease improvement.S1P is a sphingosine-derived phospholipid that acts by binding to its receptor S1PR and is involved in the regulation of several biological processes including cell survival,differentiation,migration,proliferation,immune response,and lymphocyte trafficking.T lymphocytes play an important role in regulating inflammatory responses.In inflamed IBD tissue,an imbalance between T helper(Th)and regulatory T lymphocytes and Th cytokine levels was found.The S1P/S1PR signaling axis and metabolism have been linked to inflammatory responses in IBD.S1P modulators targeting S1PRs and S1P metabolism have been developed and shown to regulate inflammatory responses by affecting lymphocyte trafficking,lymphocyte number,lymphocyte activity,cytokine production,and contributing to gut barrier function.

High-power xenon lamp-pumped Er:YAP pulse laser operated in free-running and acousto-optical Q-switching modes

We demonstrate a high-energy and high-power pulse laser on a xenon lamp-pumped Er:YAP crystal. The laser performance and thermal focal lengths under different working frequencies are discussed. The results show that the thermal lens effect is gradually aggravated with the increase of working frequencies, and even working at 100 Hz, a single pulse energy of 234 m J can be achieved. A maximum average power of 41.5 W is achieved with a working frequency of 20 Hz and slope efficiency of 2.82%. This output power is much higher than other xenon lamp-pumped erbium laser devices.A Q-switched laser is demonstrated by using the TeO2crystal, the maximum output energies of 11.5 m J and 3.5 m J are obtained at 50 and 100 Hz, the corresponding peak powers are 93.4 k W and 17.2 kW, respectively.The laser wavelengths and beam quality factors are also characterized in the free-running and Q-switched modes. A higher pulse energy and peak power laser could be achieved further by improving the damage threshold of TeO2acousto-optical Q-switching. All the experimental results illustrate that the xenon lamp-pumped Er:YAP laser is a promising candidate for high-power and high-frequency mid-infrared laser devices.

A Novel Multiple DBC-staked units Package to Parallel More Chips for SiC Power Module

Silicon carbide(SiC) power modules play an essential role in the electric vehicle drive system. To improve their performance, reduce their size, and increase production efficiency, this paper proposes a multiple staked direct bonded copper(DBC) unit based power module packaging method to parallel more chips. This method utilizes mutual inductance cancellation effect to reduce parasitic inductance. Because the conduction area in the new package is doubled, the overall area of power module can be reduced. Entire power module is divided into smaller units to enhance manufacture yield, and improve design freedom. This paper provides a detailed design, analysis and fabrication procedure for the proposed package structure. Additionally, this paper offers several feasible solutions for the connection between power terminals and DBC untis. With the structure, 18dies were paralleled for each phase-leg in a econodual size power module. Both simulation and double pulse test results demonstrate that, compared to conventional layouts, the proposed package method has 74.8% smaller parasitic inductance and 34.9% lower footprint.

Development of miniaturized SAF-LIBS with high repetition rate acousto-optic gating for quantitative analysis

The self-absorption effect in laser-induced breakdown spectroscopy(LIBS)reduces the accuracy of quantitative measurement results.The self-absorption-free LIBS(SAF-LIBS)has been proved to directly capture the optically thin plasma spectra by setting an appropriate exposure time.In this work,a novel SAF-LIBS technique with high repetition rate acousto-optic gating is developed,in which an acousto-optic modulator is used as the shutter to diffract the optically thin fluorescence,and a high repetition rate laser is used to produce quasi-continuous plasmas to enhance the integral spectral intensity,so that the CCD spectrometer can replace an intensified CCD(ICCD)and echelle spectrometer in SAF-LIBS.Experimental results show that the average absolute prediction error of aluminum is reduced to 0.18%,which is equivalent to that of traditional SAF-LIBS.This technique not only effectively shields continuous background radiation and broadened spectral lines in optically thick plasma,but also has advantages of miniaturization,low cost,convenience and reliability.

Waveguide-integrated optical modulators with two-dimensional materials

Waveguide-integrated optical modulators are indispensable for on-chip optical interconnects and optical computing.To cope with the ever-increasing amount of data being generated and consumed,ultrafast waveguide-integrated optical modulators with low energy consumption are highly demanded.In recent years,two-dimensional(2D)materials have attracted a lot of attention and have provided tremendous opportunities for the development of high-performance waveguide-integrated optical modulators because of their extraordinary optoelectronic properties and versatile compatibility.This paper reviews the state-of-the-art waveguide-integrated optical modulators with 2D materials,providing researchers with the developing trends in the field and allowing them to identify existing challenges and promising potential solutions.First,the concept and fundamental mechanisms of optical modulation with 2D materials are summarized.Second,a review of waveguide-integrated optical modulators employing electro-optic,all-optic,and thermo-optic effects is provided.Finally,the challenges and perspectives of waveguide-integrated modulators with 2D materials are discussed.

Influence of substrate effect on near-field radiative modulator based on biaxial hyperbolic materials

Relative rotation between the emitter and receiver could effectively modulate the near-field radiative heat transfer(NFRHT)in anisotropic media.Due to the strong in-plane anisotropy,natural hyperbolic materials can be used to construct near-field radiative modulators with excellent modulation effects.However,in practical applications,natural hyperbolic materials need to be deposited on the substrate,and the influence of substrate on modulation effect has not been studied yet.In this work,we investigate the influence of substrate effect on near-field radiative modulator based onα-MoO_(3).The results show that compared to the situation without a substrate,the presence of both lossless and lossy substrate will reduce the modulation contrast(MC)for different film thicknesses.When the real or imaginary component of the substrate permittivity increases,the mismatch of hyperbolic phonon polaritons(HPPs)weakens,resulting in a reduction in MC.By reducing the real and imaginary components of substrate permittivity,the MC can be significantly improved,reaching 4.64 forε_(s)=3 at t=10 nm.This work indicates that choosing a substrate with a smaller permittivity helps to achieve a better modulation effect,and provides guidance for the application of natural hyperbolic materials in the near-field radiative modulator.

Hypertrophic Scar Formation and Wound Healing Modulation Fatty Acids as Modulators of Severe Scars

Scar tissue usually generates severe discomfort in the short and long term. Common symptoms include anesthetics sequelae, pruritus, joint malfunction, new wounds on the scar surface, and pain. There are several treatments for scars, like compression, topical or intralesional steroid infiltration, 5-fluorouracil, dermabrasion, and surgeries with new scar tissue. For adult patients, it is easier to choose the treatment. However, compression is commonly applied in children to prevent treatments that have adverse effects. This study reports the outcomes of 15 patients submitted to abdominoplasty, traumatic wounds and post-burn scar treatments, which showed significant changes after the continuous use of an ointment composed of petrolatum, cod liver oil, BHT, Chamomilla recutita (chamomile) oil, Helianthus annuus (sunflower) oil, and Prunus amygdalus dulcis (sweet almond) oil. As components of the stratum corneum, unsaturated fatty acids influence the cutaneous structural and immune status and permeability. They also interfere with the maturation and differentiation of the stratum corneum and inhibit the production of proinflammatory eicosanoids, reactive species (ROS and RNS), and cytokines, thereby influencing the inflammatory response and possibly wound healing. This article aims to share our experience with the regular use of an ointment in adult and pediatric patients for three months. The increase in proinflammatory cytokine production at wound sites, resulting in a noninvasive, therapeutical, and effective cutaneous wound healing and scarring modulation, may provide a physiopathological explanation for the fast improvement of scars.

Design of Protograph LDPC-Coded MIMO-VLC Systems with Generalized Spatial Modulation

This paper investigates the bit-interleaved coded generalized spatial modulation(BICGSM) with iterative decoding(BICGSM-ID) for multiple-input multiple-output(MIMO) visible light communications(VLC). In the BICGSM-ID scheme, the information bits conveyed by the signal-domain(SiD) symbols and the spatial-domain(SpD) light emitting diode(LED)-index patterns are coded by a protograph low-density parity-check(P-LDPC) code. Specifically, we propose a signal-domain symbol expanding and re-allocating(SSER) method for constructing a type of novel generalized spatial modulation(GSM) constellations, referred to as SSERGSM constellations, so as to boost the performance of the BICGSM-ID MIMO-VLC systems.Moreover, by applying a modified PEXIT(MPEXIT) algorithm, we further design a family of rate-compatible P-LDPC codes, referred to as enhanced accumulate-repeat-accumulate(EARA) codes,which possess both excellent decoding thresholds and linear-minimum-distance-growth property. Both analysis and simulation results illustrate that the proposed SSERGSM constellations and P-LDPC codes can remarkably improve the convergence and decoding performance of MIMO-VLC systems. Therefore, the proposed P-LDPC-coded SSERGSM-mapped BICGSMID configuration is envisioned as a promising transmission solution to satisfy the high-throughput requirement of MIMO-VLC applications.

High photoelectric conversion efficiency and fast relaxation time of FA_(0.4)MA_(0.6)PbI_(3) applied in ultrafast modulation of terahertz waves

Active control of terahertz(THz)waves is attracting tremendous attentions in terahertz communications and active photonic devices.Perovskite,due to its excellent photoelectric conversion performance and simple manufacturing process,has emerged as a promising candidate for optoelectronic applications.However,the exploration of perovskites in optically controlled THz modulators is still limited.In this work,the photoelectric properties and carrier dynamics of FA_(0.4)MA_(0.6)PbI_(3)perovskite films were investigated by optical pumped terahertz probe(OPTP)system.The ultrafast carrier dynamics reveal that FA_(0.4)MA_(0.6)PbI_(3)thin film exhibits rapid switching and relaxation time within picosecond level,suggesting that FA_(0.4)MA_(0.6)PbI_(3)is an ideal candidate for active THz devices with ultrafast response.Furthermore,as a proof of concept,a FA_(0.4)MA_(0.6)PbI_(3)-based metadevice with integrating plasma-induced transparency(PIT)effect was fabricated to achieve ultrafast modulation of THz wave.The experimental results demonstrated that the switching time of FA_(0.4)MA_(0.6)PbI_(3)-based THz modulator is near to 3.5 ps,and the threshold of optical pump is as low as 12.7μJ cm^(-2).The simulation results attribute the mechanism of ultrafast THz modulation to photo-induced free carriers in the FA_(0.4)MA_(0.6)PbI_(3)layer,which progressively shorten the capacitive gap of PIT resonator.This study not only illuminates the potential of FA_(0.4)MA_(0.6)PbI_(3)in THz modulation,but also contributes to the field of ultrafast photonic devices.

Exploring the modulatory role of bovine lactoferrin on the microbiome and the immune response in healthy and Shiga toxin‑producing E.coli challenged weaned piglets

Background Post-weaned piglets suffer from F18+Escherichia coli(E.coli)infections resulting in post-weaning diar-rhoea or oedema disease.Frequently used management strategies,including colistin and zinc oxide,have contrib-uted to the emergence and spread of antimicrobial resistance.Novel antimicrobials capable of directly interacting with pathogens and modulating the host immune responses are being investigated.Lactoferrin has shown promising results against porcine enterotoxigenic E.coli strains,both in vitro and in vivo.Results We investigated the influence of bovine lactoferrin(bLF)on the microbiome of healthy and infected weaned piglets.Additionally,we assessed whether bLF influenced the immune responses upon Shiga toxin-producing E.coli(STEC)infection.Therefore,2 in vivo trials were conducted:a microbiome trial and a challenge infection trial,using an F18+STEC strain.BLF did not affect theα-andβ-diversity.However,bLF groups showed a higher relative abundance(RA)for the Actinobacteria phylum and the Bifidobacterium genus in the ileal mucosa.When analysing the immune response upon infection,the STEC group exhibited a significant increase in F18-specific IgG serum levels,whereas this response was absent in the bLF group.Conclusion Taken together,the oral administration of bLF did not have a notable impact on theα-andβ-diversity of the gut microbiome in weaned piglets.Nevertheless,it did increase the RA of the Actinobacteria phylum and Bifi-dobacterium genus,which have previously been shown to play an important role in maintaining gut homeostasis.Furthermore,bLF administration during STEC infection resulted in the absence of F18-specific serum IgG responses.

Enhancing quantum temporal steering via frequency modulation

Various strategies have been proposed to harness and protect space-like quantum correlations in different models under decoherence.However,little attention has been given to temporal-like correlations,such as quantum temporal steering(TS),in this context.In this work,we investigate TS in a frequency-modulated two-level system coupled to a zero-temperature reservoir in both the weak and strong coupling regimes.We analyze the impact of various frequency-modulated parameters on the behavior of TS and non-Markovian.The results demonstrate that appropriate frequency-modulated parameters can enhance the TS of the two-level system,regardless of whether the system is experiencing Markovian or non-Markovian dynamics.Furthermore,a suitable ratio between modulation strength and frequency(i.e.,all zeroes of the 0th Bessel function J_(0)(δ/?))can significantly enhance TS in the strong coupling regime.These findings indicate that efficient and effective manipulation of quantum TS can be achieved through a frequency-modulated approach.

Experimental realization of fractal fretwork metasurface for sound anomalous modulation

Natural creatures and ancient cultures are full of potential sources to provide inspiration for applied sciences.Inspired by the fractal geometry in nature and the fretwork frame in ancient culture,here we design the acoustic metasurface to realize sound anomalous modulation,which manifests itself as an incident-dependent propagation behavior:sound wave propagating in the forward direction is allowed to transmit with high efficiency while in the backward direction is obviously suppressed.We quantitatively investigate the dependences of asymmetric transmission on the propagation direction,incident angle and operating frequency by calculating sound transmittance and energy contrast.This compact fractal fretwork metasurface for acoustic anomalous modulation would promote the development of integrated acoustic devices and expand versatile applications in acoustic communication and information encryption.

Microwave electrometry with Rydberg atoms in a vapor cell using microwave amplitude modulation

We have theoretically and experimentally studied the dispersive signal of the Rydberg atomic electromagneticallyinduced transparency(EIT)Autler–Townes(AT)splitting spectra obtained using amplitude modulation of the microwave(MW)electric field.In addition to the two zero-crossing points interval△f_(zeros),the dispersion signal has two positive maxima with an interval defined as the shoulder interval△f_(sho),which is theoretically expected to be used to measure a much weaker MW electric field.The relationship of the MW field strength E_(MW)and△f_(sho)is experimentally studied at the MW frequencies of 31.6 GHz and 9.2 GHz respectively.The results show that△f_(sho)can be used to characterize the much weaker E_(MW)than that of△f_(zeros)and the traditional EIT–AT splitting interval△f_(m);the minimum E_(MW)measured by△f_(sho)is about 30 times smaller than that by△f_(m).As an example,the minimum E_(MW)at 9.2 GHz that can be characterized by△f_(sho)is 0.056 mV/cm,which is the minimum value characterized by the frequency interval using a vapor cell without adding any auxiliary fields.The proposed method can improve the weak limit and sensitivity of E_(MW)measured by the spectral frequency interval,which is important in the direct measurement of weak E_(MW).

Engineering vascularized organotypic tissues via module assembly

Adequate vascularization is a critical determinant for the successful construction and clinical implementation of complex organotypic tissue models. Currently, low cell and vessel density and insufficient vascular maturation make vascularized organotypic tissue construction difficult,greatly limiting its use in tissue engineering and regenerative medicine. To address these limitations, recent studies have adopted pre-vascularized microtissue assembly for the rapid generation of functional tissue analogs with dense vascular networks and high cell density. In this article, we summarize the development of module assembly-based vascularized organotypic tissue construction and its application in tissue repair and regeneration, organ-scale tissue biomanufacturing, as well as advanced tissue modeling.

Age of Information for Short-Packet Covert Communication with Time Modulated Retrodirective Array

In this paper,the covert age of information(CAoI),which characterizes the timeliness and covertness performance of communication,is first investigated in the short-packet covert communication with time modulated retrodirective array(TMRDA).Specifically,the TMRDA is designed to maximize the antenna gain in the target direction while the side lobe is sufficiently suppressed.On this basis,the covertness constraint and CAoI are derived in closed form.To facilitate the covert transmission design,the transmit power and block-length are jointly optimized to minimize the CAoI,which demonstrates the trade-off between covertness and timelessness.Our results illustrate that there exists an optimal block-length that yields the minimum CAoI,and the presented optimization results can achieve enhanced performance compared with the fixed block-length case.Additionally,we observe that smaller beam pointing error at Bob leads to improvements in CAoI.