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Future artificial intelligence circuits will require expandable electronic synapses with extremely high bit density and computing speed. In this regard, the nanostructure of two-dimensional materials achieves the goal and provides device scalability in both horizontal and vertical dimensions. In this work, we report the nonvolatile bipolar resistive switching characteristics of Ni–Al layer double hydroxide (LDH)-adsorbed thiadiazole memristors. The Ni–Al LDH-adsorbed thiadiazole memristors implement a progressive reduction process and can be used to simulate the “learning” and “forgetting” functions of biological synapses. At the same positive and negative voltage pulse width, multiple resistance stages can be observed for continuous pulse number. In addition, the application of pulse train operation scheme is an effective method to control the simulated synaptic devices during the reset process, which helps understand the nature of the evolution of conductive nanofilaments.

Resistive switching effect based on graphene-embedded poly(4-vinyl phenol) composite film by spinning coating have been investigated. The nonvolatile WORM characteristics were researched. The influence of the increasing content of graphene on the resistive switching characteristics is mainly manifested in the increase of current in high resistance state, the decrease of the threshold voltage and the decrease of the ON/OFF ratio. The nonvolatile WORM characteristics of graphene poly(4-vinyl phenol) composite thin films could be ascribed to continuous conductive pathways caused by the graphene during spin-coating of the poly(4-vinyl phenol) composites on ITO substrates.

Photothermal therapy (PTT) has been widely used for the treatment of various medical conditions due to their noninvasive and cost-effective advantages. However, the light absorption and scattering ...

The rewritable bistable memory characteristics have been studied in polymethyl methacrylate (PMMA) and carboxylated multi-walled carbon nanotubes (CNT) composite films. The sandwich structure FTO/PMMA + CNTs/Ag devices were prepared by spin coating and vacuum evaporation process. The device exhibited rewritable bistable resistive switching with switch-on voltage of ~ − 1.5 V, switch-off voltage of ~ 3.4 V, and a high ON/OFF ratio almost of 105. The rewritable behavior of the FTO/PMMA + CNTs/Ag device has been investigated by the endurance test, retention test, and the write-read-erase-reread multiple-cycle tests. The FTO/PMMA + CNTs/Ag device exhibited good retention performance for 2 × 105 s and underwent 104 read pulses. The conduction mechanism in ON state obeys Ohmic conduction; simultaneously, for OFF state, trap-limited space-charge limited conduction was discovered to be the dominant conduction mechanism.

To date, the mechanisms of Er3+ upconversion luminescence via 980 and 1530 nm excitation have been extensively investigated, however, based on discussions, they either suffer from the lack of convincing evidence or require elaborated and time-consuming numerical simulations. In this work, the steady-state and time-resolved upconversion luminescence data of Er3+-doped NaYF4 were measured, we therefore investigated the upconversion mechanisms of Er3+ on the basis of the spectroscopic observations and the simplified rate equation modeling. This work provides a relatively simple strategy to reveal the UCL mechanisms of Er3+ upon excitation with various wavelengths, which may also be used in other lanthanide ion-doped systems.

A nonvolatile resistive switching memory device based on active layers of polyvinylcarbazole (PVK) was fabricated by a spin-coating technique, and the electrical characteristics of the devices consisting of SnO2 doped with fluorine (FTO)/PVK/Ag were investigated. The experimental results revealed that the FTO/PVK/Ag device has electrical bistable nonvolatile flash memory behavior. The current remained stable for 2.3 × 103 s in both the ON state and OFF state, and the current in the ON and OFF states of the FTO/PVK/Ag device did not change substantially after 750 pulse read cycles. In addition, based on the electrochemical properties of the PVK, its resistive switching behavior was investigated. This work provides a promising solution for the development of polymer memory devices.

Various concentrations of Ho3+ and Nd3+ codoped NaYF4 nanorods were successfully synthesized. On the basis of the upconversion spectra under 808 nm excitation, the luminescence mechanisms were discussed in detail. The ratio of red to green intensity evidently increases with increasing the Nd3+ content due to the stronger interactions between Ho3+ and Nd3+, which enhance the red emission and suppress the green one. In addition, we found that the red emission is more sensitive to the ambient temperature as compared to the green one, thus validating the thermal sensing by applying the ratiometric method by using these two emission bands. Relatively high sensing sensitivity of 0.9% was obtained, evidencing the great potential of the presented optical thermometer.

An optoelectronic swept-frequency laser (SFL) is an optoelectronic feedback system that includes an auxiliary interferometer that can exert precise control over the optical frequency sweep. The arm-length difference (ALD) of the auxiliary interferometer directly affects the performance of the whole system. We established a theoretical model to choose the optimal ALD of an auxiliary interferometer in an optoelectronic SFL system using a frequency-modulated continuous-wave reflectometry experimental setup. The experimental results indicated that, based on our system, the optimal ALD was 7 m, which agreed with the theoretical analysis. As an example application, we implemented the proposed system for measurement of the group refractive index of a glass sample. A minimum measurement error of 0.12% was obtained with the ALD of 7 m.

This paper proposes a large generator eddy current prediction method based on Bagging of Gaussian Process(GPR). Bagging ensemble learning model based on Gaussian Process Regression is proposed to predict eddy current loss. The slot wedge conductivity, slot wedge of the relative permeability, rotor outer diameter and stator outer diameter are as the input of the prediction model, and the eddy current loss is as the output. The experiments on the datasets calculated by Finite Element Model (FEM) show that the proposed approach has good predictive performance for Large generator rotor performance prediction and can be applied to practical projects.

We investigate the thermal effects of Er3+ doped tellurite glasses on the upconversion properties. It is found that the sensitivity of the thermometer based on the FIR technique increases monotonously with the decreasing doping concentration. However, low doping leads to weak upconversion intensity and further decrease the sensing accuracy, which makes it difficult to achieve the high sensitivity and accuracy simultaneously. Influences of the irradiating laser power on the sensing behaviors were studied in the purpose of enhancing the signal intensity. It is found that the heating effect of incident laser (up to hundreds of mW) can be neglected, indicating the feasibility of using high laser power and low doping sample to produce both high sensitivity and high accuracy. In addition, this paper respectively discusses the mechanisms of the upconversion processes and the concentration dependent sensitivity.

The effects of Li, as the ‘additive’, on the structures of nano-sized Al2O3 were investigated. Li evidently increased the crystallite size of γ-Al2O3, whereas it showed evident effects on neither L...

In this paper, we synthesized Er 3+ -doped Zinc oxide nanocrystals by conventional sol-gel method under 800 °C, and further mesoporous-like structure was obtained through post-annealing procedure at 1300 °C. Upconversion intensity was significantly enhanced by post-annealing, and the emission color was turned into relatively high purity red color (ratio of red to green emission is over 10). In addition, the mechanisms of post-annealing and upconversion luminescence were discussed in detail on the basis of the structural and spectral measurements.

This paper presents a theoretical model of an atomic line filter based on optical anisotropy which is induced by the combination of the selective pump and an external magnetic field. By analyzing the pumping process, we carefully elucidated the influence of the selective pump and magnetic field on the pumping process, and furthermore on the tunability and peak transmission of the filter. Different from the previously reported filter, our numerical results suggest that this type of filter has a large-scale tunability at the transmission peak position without sacrificing transmission, which is very important in free-space optical communication and lidar systems subjected to large Doppler shift.

We propose and demonstrate a cascaded distributed multichannel fiber surface plasmon resonance (SPR) refractive index (RI) sensor by using a gold film coating thickness adjustment approach. For a multimode fiber-based SPR sensor, different gold film thicknesses produce different resonance wavelengths, different dynamic ranges, and even different testing sensitivities. Therefore, we design and fabricate a cascaded distributed two–channel multimode fiber SPR sensor with the gold film thickness of 30 nm in #1 sub–channel and 60 nm in #2 sub–channel. The corresponding testing sensitivities are 1712 nm/RIU and 3038 nm/RIU with the RI range of 1.333–1.385. The experimental results indicate that, in the range of 20nm–60 nm, the smaller is the gold film thickness, the larger is the RI testing range, and the lower is the testing sensitivity, and the deeper is the resonance dip. In addition, it is worthy to say that, the testing sensitivity and the dynamic range of the cascaded distributed multichannel fiber SPR sensor keep unchanged after multiple sensing sub-channels being cascaded–connected. By using the gold film thickness adjustment approach, we overcome the limit of adjusting and separating the dynamic ranges of the multichannel fiber SPR sensors effectively.

We propose and demonstrate an all-fiber Bessel optical tweezers for multiple microparticles (yeast cells) three-dimensional (3-D) trap. To the best knowledge of us, it is the first time to achieve the 3-D stable noncontact multiple microparticles optical traps with long distance intervals by using a single all-fiber probe. The Bessel beam is produced by splicing coaxially a single-mode fiber and a step index multimode fiber. The convergence of the output Bessel beam is performed by molding the tip of the multimode fiber into a special semiellipsoid shape. The effective trapping range of the all-fiber probe is 0 to 60 μm, which is much longer than normal single fiber optical tweezers probes. The all-fiber Bessel optical probe is convenient to integrate and suitable for the lab on the chip. The structure of this fiber probe is simple, high precision, low cost, and small size, which provides new development for biological cells experiment and operation.

The application of poly(9-vinylcarbazole) (PVK) to make a composite with zinc oxide (ZnO) as the active layer has been reported. Unipolar resistive switching behaviors were observed from ITO/PVK + ZnO/Al memory devices. The reset voltages were higher than the set voltages. These devices present a low resistance state (LRS)/high resistance state (HRS) current ratio of 104 when read at −0.5 V, retaining the information for a time of 105 s. The bistable resistive switching behaviors were entirely steady within 104 cycles. The fitted results of I–V curves shown that the dominant conduction mechanisms in LRS and HRS were Ohmic conductive behavior and space-charge-limited current mechanism, respectively.

In this design, we introduced a surface plasmon resonance (SPR) fiber-sensing probe into a column chromatography (CC) system to realize on-line dynamic detection in sample separation. The refractive index of the gel around the probe would be adjusted dynamically by the concentration change of the sample during CC separation. To demonstrate the separation and on-line detection process, bovine serum albumin (BSA) and riboflavin-5-phosphate sodium (FMN-Na) are chosen as the analytes in a Sephadex gel filtration chromatography system. The results show that the apparent reversible shift of the SPR spectrum can characterize the separation process. Specifically, the separated BSA with an outflow time of 8 min can cause a resonance wavelength shift of 15.5 nm, and the FMN-Na with an outflow time of 26 min can cause a shift of 8.4 nm. This on-line dynamic detection of SPR spectra has great potential to save time and simplify the analysis process compared to the complex thin layer chromatography detection steps in traditional manual CC.

Particle size significantly affects the brightness of luminescent nanocrystals. Herein we firstly adopt a 1530 nm CW laser as the optical heating source to increase the particle size of Er3+ heavily doped nanocrystals, leading to giant enhancement of the luminescent intensity. The advantages of this method are mainly feature along the facile route, with an ultrafast process, and low threshold of the laser power density. The detailed mechanisms of the laser annealing are carefully investigated. In addition, fluorescence intensity ratio behaviours using different emission bands are comparatively investigated.

Improving luminescence efficiency is of vital importance for applications of rare-earth-doped upconversion materials. Herein, we present highly efficient upconversion nanocrystal, which is brighter than the state-of-the-art Er3+/Yb3+ co-doped core–shell material, through Er3+ heavily doping and 1530 nm excitation. Moreover, upconversion characteristics and mechanisms of Er3+ heavily doped core nanocrystals and their core–shell counterparts are investigated carefully.

Electrical characterization indicates that the nonvolatile write once read many (WORM) times/volatile static random access memory (SRAM) conversion was triggered by the composite of the oxadiazole small molecule. FTO/PMMA/Ag device possesses nonvolatile WORM memory behavior, while the FTO/PMMA+oxadiazole/Ag device shows vastly different volatile SRAM feature. The FTO/PMMA/Ag and FTO/PMMA+oxadiazole/Ag memory devices both exhibit high ON/OFF ratio nearly 104. The additive oxadiazole small molecule in the polymethyl methacrylate was suggested to form an internal electrode and serve as a channel during the charge transfer process, which is easy to both the charge transfer and back charge transfer, as a consequence, the WORM/SRAM conversion upon oxadiazole small molecule complexation was triggered. The results observed in this work manifest the significance of oxadiazole small molecule to the memory effects and will arouse the research interest about small molecule composite applied in memory devices.

With the rapid development of digital multimedia terminals, the scaling of video images has solved the needs of high-end displays for low-resolution signals and high-definition signals displayed by low-end displays. The main purpose of this article is to convert the input video image signal into a video image signal with the required resolution through video image scaling. This article mainly studies various image scaling algorithms, analyzes their advantages and disadvantages, and adopts a top-down design method to implement FPGA video scaling design and verify the correctness of the results. This article introduces various traditional image interpolation algorithms. On the basis of comparing the subjective and objective quality of the image after the summation of various algorithms, the fuzzy interpolation algorithm is used to zoom the video image. In FPGA design, horizontal scaling and vertical scaling are handled separately, which reduces the computational complexity of image upgrades and facilitates control logic and specific implementation. The experimental results of this paper show that the maximum working frequency that the designed image scaling unit can reach is 153.12 MHz, which can process 1080p video signals in real time. Video image scaling technology has broad market prospects.

To date, the white light lanthanide upconvertion consisting of RGB components usually originated from more than one type of emitter. Alternatively, Pr3+ is a fascinating lanthanide ion featuring multiple visible emission bands, including RGB components that in principle enable Pr3+ to emit white light. In this paper, we report, for the first time to our knowledge, white light upconversion through dual sensitization routes in Nd/Yb/Pr triply doped NaYF4 microrods upon 800 nm excitation. It is found that the dual sensitization is more efficient than single sensitization for Pr3+ upconversion. In addition, the temperature sensing behaviors of the proposed triply doped microrods are comparatively investigated using different emission bands. This work presents a novel white light emitting material upon 800 nm excitation, and further demonstrates the feasibility of multichannel thermometry using the proposed material.

We propose and demonstrate a novel Michelson Fabry–Perot hybrid fiber interference sensor. By integrating a Michelson interferometer in a two-core fiber and a Fabry–Perot interferometer in a micro silica-capillary, we produce the Michelson Fabry–Perot hybrid interference sensor. Owing to the structure characteristic of the micro-structured fiber, this hybrid fiber interference sensor can achieve the measurement of the axial strain and radial bending simultaneously. The measurement sensitivity of the axial train is 0.015 nm/μe and the measurement sensitivity of the radial bending is 1.393 nm/m−1.

We propose and demonstrate a reflective-distributed surface plasmon resonance (SPR) sensor based on the twin-core fiber. Firstly, we study the effects of the fiber dual tapered (DT) probe grinding angle on the SPR dynamic range. The results show that for larger grinding angles, the resonance wavelength increases, resulting in a higher testing sensitivity. By using this method, we can make the sensor operate in an optimal waveband. Secondly, on the basis of the results above, we grind the DT probe to be an asymmetric wedge shape to configure two grinding angles (6° and 17°) to realize the distributed sensing. Results show that, with the refractive index detecting a range of 1.333–1.385, we can get two separated sensing zones, 591–715 nm and 729–966 nm, the testing sensitivity are 2385 nm/RIU and 4558 nm/RIU respectively. By using this method, we can detect multiple analytes in the same sensing area simultaneously, besides that we can also effectively compensate for the errors caused by background index interference, and the refractive index change resulting from the non-specific binding, or physical absorption and others. It worth to say that by using this method, we can adjust and control the resonance wavelength by changing the fiber grinding angle, while keeping the testing sensitivity is not reduced. For practical applications, this reflective distributed fiber-based sensor is much suitable for biochemical sensing, it has small size and can enter a small testing spaces (μm scale). The diameter of the twin-core fiber is the only 125 μm, which helps to be integrated into a micro-fluidic chip. In this paper, we integrate the fiber probe into an infusion needle to simulate blood vessels on-line monitoring.

We propose and demonstrate a new single optical tweezers based on an elliptical core fiber, which can realize the trapped yeast cell rotation with a precise and simple control. Due to the elliptical shape of the fiber core, the LP11 mode beam can propagate stably. When we rotate the fiber tip, the LP11 mode beam will also rotate along with the fiber tip, which helps to realize the trapped micro-particle rotation. By using this method, we can easily realize the rotation of the trapped yeast cells, the rotating angle of the yeast cell is same as the elliptical core fiber tip.

Surface plasmon resonance (SPR) sensor has been widely used in biochemical reaction detection. With the development of SPR sensing, multi-channel SPR sensors have attracted attention owing to their potential application in multi-analyte detection. For fiber-based SPR sensor, due to the small size of the fiber core, it is hard to realize the multi-channel fiber SPR sensor based on the time division multiplexing (TDM) technology. Here we propose and demonstrate a multi-channel fiber SPR sensor based on the TDM technology by using the multi-core fiber. The multiple cores are multiple sensing zones, which equals to subdividing the traditional single fiber core into multiple independent sensing zones, realizing the multi-channel SPR sensing. This multi-channel SPR sensor has some advantages: it can realize multi-analyte detection simultaneously; it can compensate the ambient temperature variation, nonspecific binding and physical absorption and others; it can adjust working resonance wavelength shift range by adjusting the fiber grinding angle; it can work without resonance wavelength shift range overlapping by switching independent sensing channels. Besides that, we can add a sensing zone on the receiving fiber to construct the wavelength division multiplexing (WDM) sensing for each fiber core channel. By combining TDM and WDM technology, we can double the sensing channels.

Achieving controllable heating in deep tissue is of vital importance for photothermal therapies. In this work, we developed single-band red upconversion (UC) nanoparticles (NPs) as self-monitored photothermal probes. The excitation (∼800 nm) and emission (∼652 nm) of the developed UCNPs are both located in the first biological window (I-BW), reducing the optical energy dissipation caused by biological tissue. The emission spectroscopic characteristics of these UCNPs were investigated, as well as their corresponding UC mechanisms. Moreover, the light-to-heat efficiency of the UCNPs reached 40%, and the self-monitored temperature feedback was demonstrated using the highly efficient red emission. The proposed UCNPs can deepen the penetration and avoid overheating in biological tissues if used in photothermal therapies. We consider that these characteristics will favour their use as in vivo photothermal probes with feedback provided by their emission of light.

Flexible resistive switching memory devices based on graphene oxide (GO) polymer nanocomposite were prepared on flexible substrate to research the influence of bending on resistive switching behavior. The devices showed evident response in resistive switching memory characteristics to flexible bending. The 2000 cycles flexible bending leads to the switch of resistive switching memory characteristic from write-once-read-many time memory (WORM) to static random access memory (SRAM). Both WORM and SRAM memory properties are all repeatable, and the threshold switching voltage also showed good consistency. The resistive switching mechanism is attributed to the formation of carbon-rich conductive filaments for nonvolatile WORM characteristics. The bending-induced micro-crack may be responsible for the partial broken of the electrical channels, and may lead to the volatile SRAM characteristics.

To date, real-time adjusting the emitting color with high brightness remains a formidable challenge. In this work, compact core-shell upconversion nanocrystals emitting real-time tunable colors were presented. On the basis of rational design to suppress the energy dissipation and color crosstalk, highly intense green and red lights are respectively generated at the 980 and 1530 nm excitations. The proposed nanocrystals possess good color stability under different excitation intensities as well as ambient temperatures. In addition, steady-state and non-steady-state anti-counterfeiting demonstrations are performed.

We propose and demonstrate a simple method to generate a Bessel-like beam by using a graded-index multimode fiber. We splice a single-mode fiber and a graded-index multimode fiber with a defined offset (Δ x =20 μm), adjust the length ( L ) of the graded-index multimode fiber to be 400 μm, and then we can produce a Bessel-like beam with the transverse acceleration of 0.15464 μm −2 . The Bessel-like beam has the transverse self-accelerating properties which provides a new method for micro particles to be transported in a bending trajectories. This transverse self-accelerating Bessel-like beam generator based on the graded-index multimode fiber constitutes a new development for high-precision micro particles experiments and manipulations with its simple structure, high integration and small size.

This paper reports on the design, fabrication and characterization of a fiber surface plasmon resonance sensor whose design is based on the fiber butt-joint technology. We splice a single mode fiber and a multimode fiber together after they are grinded with an angular surface. We excite the surface plasmon wave by using the single mode fiber, which helps to improve the sensitivity effectively, and receive the surface plasmon resonance reflected spectrum by using the multimode fiber. Besides that, we can change the surface plasmon resonance angle by changing the single mode fiber grind angle, which provides the surface plasmon resonance wavelength adjustment.

This paper combines the characteristics of optoelectronic technology with that of bilingual teaching. The course pays attention to integrating theory with practice, and cultivating learners' ability. Reform and exploration have been done in the fields of teaching materials, teaching content, teaching methods, etc. The concrete content mainly includes five parts: selecting teaching materials, establishing teaching syllabus, choosing suitable teaching method, making multimedia courseware and improving the test system, which can arouse students’ interest in their study and their autonomous learning ability to provide beneficial references for improving the quality of talents of optoelectronic bilingual courses.