Optical micro/nanofiber enabled tactile sensors and soft actuators:A review

As a combination of fiber optics and nanotechnology,optical micro/nanofiber(MNF)is considered as an important multifunctional building block for fabricating various miniaturized photonic devices.With the rapid progress in flexible optoelectronics,MNF has been emerging as a promising candidate for assembling tactile sensors and soft actuators owing to its unique optical and mechanical properties.This review discusses the advances in MNF enabled tactile sensors and soft actuators,specifically,focusing on the latest research results over the past 5 years and the applications in health monitoring,human-machine interfaces,and robotics.Future prospects and challenges in developing flexible MNF devices are also presented.

Opto-Electronic Investigation of Wet Coating Deposition of ITO Nanopowders on Flexible Substrate Using Pulse Nd-YAG Laser

Transparent thin layer indium tin oxide was coated on polyethylene tetraphetalate (PET) substrate by means of spin coating process and its opto-electronic properties have been investigated. The surface treated by pulse Nd-YAG laser. Pulse frequency, duration and energy were, 1000 Hz, 0.2 to 20 ms and 25 to 40 J respectively. The effect of treatment on crystallization, optical properties and bonding processes of the thin layer was investigated. The results show that ITO coated on flexible PET substrates is conductive and transparent. The sheet transparency for a 350 nm thickness in the visible range is more than 83.6%. Using Nd-YAG laser increased conductivity by a factor of 100 times and causes higher bonding performances.

Analog Optical Computing for Artificial Intelligence

The rapid development of artificial intelligence(AI)facilitates various applications from all areas but also poses great challenges in its hardware implementation in terms of speed and energy because of the explosive growth of data.Optical computing provides a distinctive perspective to address this bottleneck by harnessing the unique properties of photons including broad bandwidth,low latency,and high energy efficiency.In this review,we introduce the latest developments of optical computing for different AI models,including feedforward neural networks,reservoir computing,and spiking neural networks(SNNs).Recent progress in integrated photonic devices,combined with the rise of AI,provides a great opportunity for the renaissance of optical computing in practical applications.This effort requires multidisciplinary efforts from a broad community.This review provides an overview of the state-of-the-art accomplishments in recent years,discusses the availability of current technologies,and points out various remaining challenges in different aspects to push the frontier.We anticipate that the era of large-scale integrated photonics processors will soon arrive for practical AI applications in the form of hybrid optoelectronic frameworks.

Photo-processing of perovskites:current research status and challenges

The past two decades have seen a drastic progress in the development of semiconducting metal-halide perovskites(MHPs)from both the fundamentally scientific and technological points of view.The excellent optoelectronic properties and device performance make perovskites very attractive to the researchers in materials,physics,chemistry and so on.To fully explore the potential of perovskites in the applications,various techniques have been demonstrated to synthesize perovskites,modify their structures,and create patterns and devices.Among them,photo-processing has been revealed to be a facile and general technique to achieve these aims.In this review,we discuss the mechanisms of photo-processing of perovskites and summarize the recent progress in the photo-processing of perovskites for synthesis,patterning,ion exchange,phase transition,assembly,and ion migration and redistribution.The applications of photo-processed perovskites in photovoltaic devices,lasers,photodetectors,light-emitting diodes(LEDs),and optical data storage and encryption are also discussed.Finally,we provide an outlook on photo-processing of perovskites and propose the promising directions for future researches.This review is of significance to the researches and applications of perovskites and also to uncover new views on the light-matter interactions.

Cr-Doped TiO_(2)Thin Films Prepared by Means of a Magnetron Co-Sputtering Process:Photocatalytic Application

This paper deals with the effect of Cr content on photocatalytic activity of TiO2 thin films deposited on quartz and intrinsic silicon substrates by using the RF magnetron co-sputtering process. Some physical investigations on such sputtered films were made by means of X-ray Diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy as well as UV-Vis-IR absorption techniques. The heat treatment under oxygen atmosphere at 550°C reveals that the crystalline structure of TiO2: Cr depends on Cr content. Anatase-to-rutile phase transformation occurs at a Cr content of about 7%. On the other hand, the band gap energy value of annealed TiO2: Cr films varies in terms of Cr doping and a transition around 7% of Cr is accrued. The photocatalytic activity of undoped and doped TiO2 films was evaluated by photo-degrading of the amido black under UV light irradiation. Modification of the chemical structure of titanium dioxide by Cr doping allows moving the photocatalytic activity of titanium dioxide towards visible light. The results indicate that films doped with 2% Cr exhibit the highest UV and visible light photocatalytic activity.

Coupling Analysis of Moment of Inertia & Dynamic on Optoelectronic Tracking Turntable

With photoelectric tracking system as the research object,based on the theorem of moment of momentum and Euler dynamic equation,Nonlinear biaxial coupling dynamic model of tracking turntable is established.Effects of moment of inertia coupling,speed coupling and the dynamic coupling between tracking turntable shafts were studied,the analytical relation between them was given in theory.Verify the change trend of theoretical model.And it provides the theory reference and model base,for the future design of the high precision tracking controller And control parameter selection and optimization.In the end,specific measures are made for structure optimization.

Radio Optical Network Simulation Tool (RONST)

This paper presents a radio optical network simulation tool(RONST)for modeling optical-wireless systems.For a typical optical and electrical chain environment,performance should be optimized concurrently before system implementation.As a result,simulating such systems turns out to be a multidisciplinary problem.The governing equations are incompatible with co-simulation in the traditional environments of existing software(SW)packages.The ultra-wideband(UWB)technology is an ideal candidate for providing high-speed short-range access for wireless services.The limited wireless reach of this technology is a significant limitation.A feasible solution to the problem of extending UWB signals is to transmit these signals to endusers via optical fibers.This concept implies the need for the establishment of a dependable environment for studying such systems.Therefore,the essential novelty of the proposed SW is that it provides designers,engineers,and researchers with a dependable simulation framework that can accurately and efficiently predict and/or optimize the behavior of such systems in a single optical-electronic simulation package.Furthermore,it is supported by a strong mathematical foundation with integrated algorithms to achieve broad flexibility and low computational cost.To validate the proposed tool,RONST was deployed on an ultra-wideband over fiber(UWBoF)system.The bit error rate(BER)has been calculated over a UWBoF system,and there is good agreement between the experimental and simulated results.

Highly Fluorescent Conducting Polymer Hybrid Materials Based on Polyaniline-Polyethylene Glycol-Arsenic Sulphide

Highly fluorescent binary and ternary hybrid materials based on polyaniline, polyethylene glycol (PEG) and arsenic sulphide have been prepared via oxidative chemical polymerization and characterized by FT-IR and powder X-ray diffraction techniques. Thermogravimetric analysis showed that all the materials are thermally stable up to 250℃. The optical behaviour was investigated using UV-Vis. and fluorescence spectroscopy. Fluorescence spectra of polyaniline and its hybrids were found to be concentration dependent, and concentrations were optimized to achieve maximum intensity of emission. Aggregation caused quenching (ACQ) may be the possible reason for concentration dependent emission. Hybrids showed significantly enhanced fluorescence than polyaniline. The AC electrical conductivity was also measured and found to be better for hybrids than the polyaniline. In the PAni-PEG-As2S3 hybrid, the conductivity was found to be 9.57 × 10-1 S/cm at 100 KHz. This valuable improvement in luminescent property and conducting behaviour may be useful in various optoelectronic and electronic applications.

Structural parameters improvement of an integrated HBT in a cascode configuration opto-electronic mixer

We analyze an integrated electrically pumped opto-electronic mixer, which consists of two InP/GalnAs hetero junction bipolar transistors （HBT）, in a cascode configuration. A new HBT with modified physical structure is proposed and simulated to improve the frequency characteristics of a cascode mixer. For the verification and calibrating software simulator, we compare the simulation results of a typical HBT, before modifying it and com paring it with empirical reported experiments. Then we examine the simulator on our modified proposed HBT to prove its wider frequency characteristics with better flatness and acceptable down conversion gain. Although the idea is examined in several GHz modulation, it may easily be extended to state of the art HBT cascode mixers in much higher frequency range.

A Simplified Numerical Simulation Method Considering Active Devices for Opto-Electronic Mixed Modules

A simplified simulation method based on the FDTD technique that can handle active devices is proposed. This method well suits the electrical crosstalk analysis of multi-channel integrated, opto-electronic mixed modules. We apply this method to an 8-channel integrated super-compact high-sensitivity optical module. The results show good agreement between simulations and measurements.

π-Extension of Isoindigos(IIDs)through C—H/N—H Activation and Alkyne Annulation

Isoindigo(IID)is widely used as organic dye and conjugated unit in opto-electronic materials.Functionalization of IID to increase its structural complexity is demanding for obtaining diversity properties.Herein,we developed a direct C-H/N-H activation method of IIDs via double alkyne annulations and synthesizedπ-extended IIDs with two pairs of 5/7 membered rings.The structure of theπ-extended IIDs was characterized and confirmed by^(1)H NMR,^(13)C NMR,HRMS and X ray crystal analysis.Their physical properties were characterized by UV-vis absorption,cyclic voltammetry and thermogravimetric analysis.The absorption coefficient of the annulated products enhanced significantly compared with the non-annulated analogue.

Molecular Uniting Set Identified Characteristic(MUSIC)of Organic Optoelectronic Material

Researchers investigated the organic optoelectronic materials and facilitated their development in organic light-emitting diodes(OLEDs),chemo-and biosensors,organic solar cells,data storage,and anticounterfeiting devices.Atoms make up molecules through chemical bonds,and molecular aggregates are formed through weak intermolecular interactions.The opto-electronic performance of these materials depends on not only the properties of the well-designed molecules with specific function groups,but also their aggregate states.The molecular aggregates in the form of nanoparticles can be applied in biological imaging,and films can be applied to photovoltaic and photodeformable devices,in which,the alignment of optoelectronic molecules can be either an ordered crystalline or an amorphous state.Generally,the crystalline materials could be deeply investigated by single crystal/powder X-ray diffraction analysis,which could provide the accurate information about molecular conformations,interactions and packing characteristics.It afforded a convenient way to investigate the possible relationship between molecular aggregates and opto-electronic properties.Among various opto-electronic materials,organic room temperature phosphorescence(RTP)materials exhibit the extremely sensitive luminescence property to molecular aggregates,even the dynamic properties can be detected by the tiny change of molecular aggregates.Thus,we selected the organic RTP emission as the output information of molecular aggregates,and afforded typical examples to find the possible relation between RTP effect and molecular packing.Accordingly,molecular packing can be adjusted by the external force as light,mechanical force,temperature,electric field,and so on,as well as the molecular structures as the building blocks,and the systematic investigation in the dynamic and static aggregation structures is of great value to the design of various optoelectronic materials.This review discusses the relationship among molecular structures,aggregation behaviors and corresponding optoelectronic properties by a comprehensive summary of recent research in our group,and the concept of molecular uniting set identified characteristic(MUSIC)is afforded.

Theoretical study of the low-lying electronic excited states for molecular aggregates

We present here a brief summary of a National Natural Science Foundation Major Project entitled "Theoretical study of the low-lying electronic excited state for molecular aggregates". The project focuses on theoretical investigation of the electronic structures and dynamic processes upon photo-and electric-excitation for molecules and aggregates. We aim to develop reliable methodology to predict the optoelectronic properties of molecular materials related to the electronic excitations and to apply in the experiments. We identify two essential scientific challenges: (i) nature of intramolecular and intermolecular electronic excited states; (ii) theoretical description of the dynamic processes of the coupled motion of electronic excitations and nucleus. We propose the following four subjects of research: (i) linear scaling time-dependent density-functional theory and its application to open shell system; (ii) computational method development of electronic excited state for molecular aggregates; (iii) theoretical investigation of the time evolution of the excited state dynamics; (iv) methods to predict the optoelectronic properties starting from electronic excited state investigation for organic materials and experimental verifications.

Synthesis and Characterization of Indium Niobium Oxide Thin Films via Sol—Gel Spin Coating Method

In the present study, niobium-doped indium oxide thin films were prepared by sol-gel spin coating technique. The effects of different Nb-doping contents on structural, morphological, optical, and electrical properties of the films were characterized by means of X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, atomic force microscopy （AFM）, UV-Vis spectroscopy, and four point probe methods. XRD analysis confirmed the formation of cubic bixbyite structure of In203 with a small shift in major peak position toward lower angles with addition of Nb. FESEM micrographs show that grain size decreased with increasing the Nb-doping content. Optical and electrical studies revealed that optimum opto-electronic properties, including minimum electrical resistivity of 119.4 × 10^-3 Ω cm and an average optical transmittance of 85% in the visible region with a band gap of 3.37 eV were achieved for the films doped with Nb-doping content of 3 at.%. AFM studies show that addition of Nb at optimum content leads to the formation of compact films with smooth surface and less average roughness compared with the prepared ln2O3 films.