Photoelectric Detection Research Articles

Near-unity double-mode absorber integrating graphene-dielectric-stack and metal grating

A terahertz absorber is designed by integrating the graphene dielectric stack (GDS) above and the metal grating below. The GDS is formed through arranging the graphene monolayer and dielectric film periodically. In the case of impedance matching, two near-unity absorption modes arise as the coupling result of Fabry-Perot (FP) resonance and surface plasmon polaritons (SPP) resonance. Tuning the chemical potential or the period of GDS, both modes can be shifted. Changing the period or the duty cycle of metal grating, all of the locations and amplitudes of modes along with the peak-peak distance between modes are controllable. Altering the thickness of dielectric slab, these modes move towards the same direction linearly almost. Deviating the normal incidence, the number of absorption modes can be increased. The designed graphene absorber should be useful to multiple targets sensing, photoelectric detection and frequency conversion of nonlinear system.

A Non-Volatile Tunable Terahertz Metamaterial Absorber Using Graphene Floating Gate.

Based on the graphene floating gate, a tunable terahertz metamaterial absorber is proposed. Compared with the traditional graphene–dielectric–metal absorber, our absorber has the property of being non-volatile and capacity for anti-interference. Using the finite element method, the paper investigates the absorption spectra, the electric field energy distribution, the tunability and the physical mechanism. In addition, we also analyse the influence of geometry, polarization and incident angles on the absorption. Simulation results show that the bandwidth of the absorption above 90% can reach up to 2.597 THz at the center frequency of 3.970 THz, and the maximum absorption can be tuned continuously from 14.405% to 99.864% by controlling the Fermi level from 0 eV to 0.8 eV. Meanwhile, the proposed absorber has the advantages of polarization insensitivity and a wide angle, and has potential applications in imaging, sensing and photoelectric detection.

Multi-area detection sensitivity calculation model and detection blind areas influence analysis of photoelectric detection target

Multi-element array photoelectric detector is the core devices to form a photoelectric detection target with a large field of view. This photoelectric detection target brings about the problem of uneven detection sensitivity distribution in the detection screen. To improve the uneven detection sensitivity of this photoelectric detection target, this paper analyzes the distribution law of the uneven detection sensitivity of the photoelectric detection target using the multi-element array photoelectric detector, dissects the main factors affecting the detection sensitivity according to the photoelectric detection principle, establishes the calculation model of detection sensitivity of the photoelectric detection target in the different detection areas and proposes a method to improve the detection sensitivity by compensating the gain of each unit photoelectric detector. The analysis of simulation and experimental results show that the proposed method of photoelectric detection target can effectively improve the output signal amplitude of the projectile under the certain detection distance, in particular, the output signal amplitude of the projectile is significantly increased when the projectile passes through the detection blind area. The experimental results are consistent with the simulation results, which verify the effectiveness of the proposed improvement method.

Detection sensitivity correction calculation model and application of photoelectric detection target in four-screen intersection testing system

In four-screen intersection testing system, the inconsistency in the detection sensitivity of the photoelectric detection target leads to the errors in the time value extraction for each photoelectric detection target. To improve the detection sensitivity and the measurement accuracy, we propose the array photoelectric detection receiver to design a new photoelectric detection target, set up a new method for calculating the detection sensitivity of the photoelectric detection target based on the detection field of view, detection screen thickness, detection distance, and the target’s geometry, and present a detection sensitivity correction method for four-screen intersection testing system by introducing the sensitivity correction factor. Through the comparative experiments, we present the comparative test data when the projectile passes through different positions of the field of view of photoelectric detection target for different detection distances. The results show that the proposed detection sensitivity correction model has the ability to improve the measurement accuracy.

High selectivity color filters based on bismuth enhanced plasmonic nanorods

In view of the low intensity of surface plasmon resonance in nanorod-array based color filters, we propose a Bi-SiO2-Ag nanorod array color filter, which takes advantage of the perfect absorption of the incident light by bismuth and the enhancement effect of metal–insulator–metal (MIM) cavity on localized surface plasmon resonance. By changing the thickness of silicon dioxide in the middle layer to adjust the resonance wavelength and using the COMSOL Multiphysics software to study and verify, we show that the proposed device can achieve filtering effect in the visible and near-infrared spectrum range, leading to up to 95% reflectivity in a specific wavelength range. In addition, the full width at half maximum (FWHM) of the device is considerably lower than that of traditional metallic materials, significantly reducing color crosstalk. Therefore, it can be used as a reflective color filter. The proposed structure has many potential applications in the fields of photoelectric detection, image sensing and display.

Interface engineering of ferroelectric-gated MoS2 phototransistor

Two-dimensional (2D) layered materials have received significant attention owing to their unique crystal structures as well as outstanding optical and electric properties in photoelectric detection. However, most 2D materials are very sensitive to the environment. Adsorbates and traps introduced during the preparation process have a negative effect on the performance of devices based on these materials. Here, we focus on a molybdenum disulfide (MoS$_{2}$) phototransistor gated by ferroelectrics, and insert a hexagonal boron nitride (h-BN) layer between MoS$_{2}$ and the ferroelectric film to improve the interface. To clarify thelinebreak role of h-BN in this device, two parallel devices are prepared on the same MoS$_{2}$ flake. One device is covered with h-BN, while the other is in direct contact with the ferroelectric film. The electronic and optoelectronic properties of these two devices are then measured and compared. Experimental results reveal that, compared to device without h-BN, the MoS$_{2}$ phototransistor with h-BN exhibits higher carrier mobility (average value: 85 cm$^{2}$$\\cdot$V$^{-1}$$\\cdot$s$^{-1}$ and highest value: 185 cm$^{2}$$\\cdot$V$^{-1}$$\\cdot$s$^{-1}$), larger responsivity (85 A$\\cdot$W$^{-1}$), and larger detectivity ($1.76~\\times~10^{13}$ Jones). Thus, this strategy is significant for the interface engineering and performance improvement of devices based on 2D materials.

Dual-band and polarization-independent metamaterial terahertz narrowband absorber.

A dual-band terahertz metamaterial narrowband absorber is investigated based on a single simple windmill-shaped structure. The proposed metamaterial absorber achieves near-perfect absorption at 0.371 THz and 0.464 THz. The full width at half-maximum is 0.76% and 0.31% relative to absorption frequency. The multireflection interference theory is used for analyzing the absorption mechanism at low absorption frequency. The theoretical predictions of the decoupled model have excellent agreement with simulation results. By investigating the absorber's distribution of electric field and surface current density at high absorption frequency, the absorber's near-perfect absorption at the high absorption frequency originating from the magnetic resonance formed between the top metal structure and the bottom metal plane is explained. Besides, the absorber proposed is independent of the polarization angle. It is significant to various applications such as narrowband thermal radiation, photoelectric detection, biological sensing, and other fields.

Design and Fabrication of Double-Layer Curved Compound Eye via Two-Photon Polymerization

A kind of double-layer curved compound eye (DLCCE) inspired by natural compound eye was developed and fabricated in two-photon polymerization (TPP) technology to solve the existing problems, such as defocus at the edge, hard to miniaturize, assemble and detect. For each ommatidium, a corresponding modified microlens was designed to refract and focus the incident rays on the photoelectric detector. The diameter of the complete compound eye is 47.9 μm. It is integrated by 33 ommatidia with a diameter of 3.9 μm and possesses a theoretical FOV angle of 85°. What's more, extra supports and through-holes were designed to promote to develop the unpolymerized photoresist within the fabricated structure. An imaging experiment was conducted to demonstrate the validity of developed compound eye comparing with the single-layer one. This work was expected to promote compound eyes to be applied in more imaging and sensing fields of microvision for their miniaturization, integration and optimization of optical system.

Study on the Laser Beam Polarization Based on LabVIEW

With the wide application of laser technology in laser processing and photoelectric detection, the measurement and display of the laser beam polarization has become an extremely important prerequisite. In this paper, we realize the laser polarization measurement tool based on the virtual instrument LabVIEW software platform. The set-up is designated to measure the Stokes parameters for an arbitrarily polarized beam, using the rotating waveplate method provided by the stepper motor, drive circuit, photodetector, and computer processing of the digitized electrical signal in the PCI expansion card. The Poincare sphere is used for the interpretation of the state of polarization (SOP) and degree of polarization (DOP). The working wavelength range is declared to be 400 – 1100 nm, the accuracy of DOP, azimuth measurement, and ellipticity are ±2%, 0.4°, and 0.4°, respectively.

Short-Wave Near-Infrared Polarization Sensitive Photodetector Based on GaSb Nanowire

The near-infrared (NIR) polarized photodetector has wide range of applications including the object identification. Wavelength of 1550 nm is the least loss band for transmission communication, and the study of photodetectors working at 1550 nm demonstrate special scientific and applied significances. GaSb has attracted tremendous attention in the field of photoelectric detection due to its suitbale band gap, high mobility, sensitivity, and good compatibility with modern microelectronics technology. In this work, a highly polarization-sensitive GaSb nanowire-based photodetectors under short-wave near-infrared photoelectric detection is achieved. The device has a good optical detection ability in the near-infrared band, and showed the responsivity up to 77.3 A/W with the external quantum efficiency of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.18\times 10 ^{3}$ </tex-math></inline-formula> % (illumination intensity of 1.59 mW/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) under 1550 nm. Furthermore, obvious photocurrent anisotropy are investigated under the near-infrared band from 808 nm to 1550 nm. The largest dichroic ratio reaches 3.3 at 1550 nm. These results indicate that GaSb nanowire based photodetectors are not only promising candidates for NIR detection but also have promising potentials in polarization sensitive applications.

Photoelectric Detection of Hole Shape and Size for Large Plate Parts

The measurement of hole shape and size of large plate parts has always been a technical problem. The article proposes a technology to use non-contact photoelectric detection technology for online detection of the shape and position of large plate-shaped workpieces. The detection principle is: the control system controls the photoelectric detection system to move in a straight line along the guide rail at a uniform speed, and the large plate-shaped workpiece the hole shape and size are measured, and the lighting system moves synchronously with the photoelectric detection system to provide the light source for it. The images collected by the photoelectric detection system are processed through digital image processing and image splicing technology to realize the hole shape and size of large plate workpieces. Non-contact measurement.

A Fire Warning Method Using Tunable Diode Laser Absorption Spectroscopy

Tunable diode laser absorption spectroscopy (TDLAS) technology is adopted herein to detect fire gas produced in the early stage of the fire. Based on this technology, a fire warning detection system with multiple lasers and detectors is proposed. Multiple drivers input laser’s temperature and injected current data, making its output wavelength consistent with the measured gas’ absorption peak wavelengths in absorption spectroscopy. Multiple light beams are coupled to the same optical fiber. After the light beams pass through the long optical path absorption cell filled with fire gas, the beams are separated by a converter. The signals are demodulated by different detectors and further analyzed for fire warnings. After the fire warning system’s design, the system’s various hardware modules are designed, including the light source module, TDLAS controller, gas chamber module, photoelectric detector, and data collection. When the temperature remains unchanged, the output wavelength is linearly related to the injected current. When the injected current remains unchanged, the output wavelength is linearly related to the operating temperature. With a semiconductor laser’s injected current of 40 mA, the initial temperature of 38.6 °C, and the output wavelength of 1578.16 nm, the output wavelength increases continuously as the temperature increases. The harmonic signal amplitude after gas absorption is positively correlated with the measured gas concentration, indicating that the second harmonic signals can estimate the fire gas concentration.

Optoelectrical Switching of Nonfullerene Acceptor Y6 and BPQD‐Based Bulk Heterojunction Memory Device through Photoelectric Effect

AbstractThe as‐prepared BPDQs:Y6:PVP blends, in which Y6 acts as nonfullerene acceptor, black phosphorus quantum dots (BPQDs) serve as donor, and polyvinylpyrrolidone (PVP) as a polymer matrix, can respond to both the electrical and optical stimuli. Using these blends as the active layer, the first bulk heterojunction device with the functions of organic photovoltaics and information storage, Al/BPQDs:Y6:PVP/indium tin oxide, is fabricated. When the applied voltages vary from 0 to −0.8 V, this device exhibits both the photoinduced resistive state changes and volatile photoresponse characteristic in the broadband visible region. The light illumination gives rise to the significantly decrease of the device resistance. Furthermore, it is also found that, when the applied voltages are changed from 0 to ± 3 V, this device shows a typical nonvolatile rewritable memory performance in the dark, with an ON/OFF current ratio of 8 × 103, a switching‐on voltage of −1.68 V, and a smaller switching bias window. Upon illumination with different wavelength light, both the switching‐on voltage and the ON/OFF current ratio of the device are found to be greatly decreased. This work can be expected to open a way to the integration of information storage, modulating and demodulating functions, photovoltaic effect, and photoelectric detection in an optoelectronic device.

Ultrathin two-dimensional Fe-doped cobaltous oxide as a piezoelectric enhancement mechanism in quartz crystal tuning fork (QCTF) photodetectors.

An innovative ultrathin two-dimensional (2D) Fe-doped cobaltous oxide (Fe-CoO) coated quartz crystal tuning fork (QCTF) was introduced for the purpose of developing a low-cost photoelectric detector with a simple configuration. The enhancement mechanism of the piezoelectric signal in the ultrathin 2D Fe-CoO-coated QCTF detector is assumed to be the synergetic photocarrier transfer and photothermal effect of ultrathin 2D Fe-CoO. The ultrathin 2D nanosheet structure of Fe-CoO with a large specific surface area can efficiently absorb and convert light into heat in the QCTF, and the photocarrier transfer from the Fe-CoO nanosheet to the electrode of the QCTF contributes to the enhancement in electricity given the shortened diffusion distance of carriers to the surfaces of the 2D nanosheet. Finite element modeling was adopted to simulate the thermoelastic expansion and mechanical resonance of the QCTF with 2D Fe-CoO coating to support experimental results and analyses. Moreover, the effects of 2D Fe-CoO on the performance of QCTF-based photoelectric detectors were investigated. This Letter demonstrates that ultrathin 2D materials have great potential in applications such as costly and tiny QCTF detectors, light sensing, biomedical imaging, and spectroscopy.

Polarization-dependent and tunable absorption of terahertz waves based on anisotropic metasurfaces

Metamaterial absorbers can achieve high-efficiency electromagnetic absorption in a specific band, which have been used in biochemical sensing, photoelectric detection, imaging and other fields. Tunable metamaterial absorbers provide more possibilities for the development of multifunctional electromagnetic absorption devices. Here we propose a tunable and polarization-dependent terahertz metamaterial absorber which can work for both linearly and circularly polarized waves. By introducing single layer graphene and vanadium dioxide (VO2), switching between the two working states and wide-range tuning of the absorption efficiency are realized. When VO2 is in insulating state, the absorber shows different tunable absorption performance for the x- or y-polarized terahertz waves, in which the maximum absorption rate is close to 100%. When VO2 is in metallic state, the metasurface behaves as a chiral absorber, and the maximum absorption difference between the two circular polarizations is about 0.45, while the tuning efficiency reaches 86.3%. Under the two working conditions, the absorber can maintain efficient absorption with a large incident angle. In addition, as an application exploration of the absorber, we demonstrated its application in tunable and polarization multiplexed near-field image display.

First-principles computations of elastic, electronic, and optical properties of zero-dimensional perovskite Cs3BiX6 (X = Br, Cl)

Halogenated perovskite materials AmBnXq have attracted significant attention owing to their special photoelectric properties. The photoelectric properties of AmBnXq are strongly related to the geometric connectivity of their [BX] group constituents, which can be defined as their “dimensionality.” As a newly synthesized compound, Cs3BiX6 (X = Br, Cl) has a crystal structure composed of cation Cs+ and [BiX6]3- groups through ionic bonds. There are no links among [BiX6]3-, and thus Cs3BiX6 is considered to have a zero-dimensional structure. In this study, the elastic, electronic, and optical properties of Cs3BiX6 are studied in detail using first principles computations. The results show that Cs3BiX6 is a broadband direct semiconductor. The band structure of Cs3BiX6 without a spin orbit coupling effect is compared with that when considering the spin orbit coupling effect. It was found that the band gap of Cs3BiX6 decreases significantly owing to its spin orbit coupling effect. Five absorption peaks of Cs3BiBr6 are located at 4.88, 8.06, 10.34, 14.7, and 25.7 eV, which correspond closely to the wavelengths of 254, 154, 120, 84, and 48.4 nm within the ultraviolet region, respectively. Therefore, Cs3BiX6 has potential applications for use in ultraviolet photoelectric detectors.

Fiber Optical Hydrogen Sensor Based on WO3-Pd2Pt-Pt Nanocomposite Films.

In this paper, WO3-Pd2Pt-Pt nanocomposite films were deposited on a single mode fiber as the hydrogen sensing material, which changes its reflectivity under different hydrogen concentration. The reflectivity variation was probed and converted to an electric signal by a pair of balanced InGaAs photoelectric detectors. In addition, the performance of the WO3-Pd2Pt-Pt composite film was investigated under different optical powers, and the irrigating power was optimized at 5 mW. With the irrigation of this optical power, the hydrogen sensitive film exhibits quick response toward 100 ppm hydrogen in air atmosphere at a room temperature of 25 °C. The experimental results demonstrate a high resolution at 5 parts per million (ppm) within a wide range from 100 to 5000 ppm in air. This simple and compact sensing system can detect hydrogen concentrations far below the explosion limit and provide early alert for hydrogen leakage, showing great potential in hydrogen-related applications.

Light trapping in ZnO nanowires to control ultraviolet photodetection responsivity

The ZnO planar thin-layer usually suffers from low-light absorbing ability because of its short transmission path of incident light. Herein, we demonstrate a series of high-performance ZnO nanowires array ultraviolet photodetectors via hydrothermal synthesis. In conjunction with ZnO nanowires array, which shows strong light trapping effect, the light absorbing ability of ZnO photodetectors is greatly enhanced. Using optical transmission and photocurrent measurements on ZnO photodetectors, it is shown that the ordered arrays of ZnO nanowires increase the light responsivity. Furthermore, in the case of nanowires length growth, it is confirmed that the photon path length and path length enhancement factor also increases, thus reducing the loss of light, and reflecting a large amount of light on ZnO film, which is then collected. The light trapping effect of ZnO nanowires ultraviolet photodetectors exhibits higher photo-to-dark current ratio above 104, where photoresponsivity reaches 14.50 A W−1 and excellent detectivity (~1012 Jones). The light trapping effect of nanomaterials is applied to the research of photoelectric detectors, which provides a new perspective for photoelectric materials.

Photoelectric Detection System and Machine Learning Recognition Method of Its Detection Images

In the photoelectric detection system, the photoelectric detector can convert the optical signal to be measured into a current signal, and the current amplifier transforms the current signal output by the detector into a voltage signal for amplification. In this study, the photo-multiplier tube (PMT) is selected as the photoelectric detector. Compared with other photoelectric detectors, it can obtain higher internal gain, higher sensitivity, and better response performance. The current amplifier is prepared by pre-amplifier and voltage amplifier. In order to capture photoelectric signals well, a large-format scanning system is set up to design each component module, control module, and host computer module of the system. Besides, a machine learning-based algorithm is proposed, namely semi-supervised manifold image recognition algorithm, which is used for identify photoelectric detection images. In the test process, the printed circuit board (PCB) and sapphire material are firstly used as the substrate of the current amplifier, and their influences in the circuit are compared. The peak value of the output noise of each substrate circuit is around 2.8 mV when the input of the current amplifier is short-circuited. Then, the signal gain and signal bandwidth of the photoelectric detection system remain stable when there is no optical signal input. During the process of changing the system signal gain ratio, the noise output of the system is the lowest when the voltage of PMT is 0.50 V and the current amplifier gain is set to 2.2 × 105 V/A. The proposed recognition algorithm can identify different types of targets well. After the image is projected into a two-dimensional space by the algorithm, the distance between classes increases, and the targets in the class promote aggregation, thereby enhancing the identify-ability between samples.

A Wide-Angle, Enhanced Oblique Incidence, Bend-Able Metamaterial Absorber Employed in Visible Region With a Sun Shape Resonator

Solar spectrum is supposed to be a key source of renewable energy in the form of electromagnetic (EM) radiation. For efficiently harnessing this abundant energy, Metamaterial Absorber (MMA) emerges as a game-changing tool. Along with solar energy harvesting, MMA can be used in biochemical sensors, optical modulators, magnetic resonance imaging, photoelectric detectors, plasmonic sensors, etc. In this paper, a sun shape resonator-based MMA is designed with three layers of materials (W-SiO2-W) and analysed for broadband absorption encompassing the entire visible region (390-760nm). The unit cell that is presented in this study is polarization-insensitive and ultrathin with an average absorption of 96.43% with an optimum peak of 99.99% at 523.22nm. The proposed MMA exhibits satisfactory absorption under various oblique angles. The effect of mechanical loading is also investigated and the MMA is found to hold good broadband absorbance for some extents of mechanical bending. Finite Integration Technique (FIT) is used to numerically simulate the proposed MMA unit cell structure and validated with the Finite Element Method (FEM). The suggested MMA in this paper can be used in many optical applications like efficient nano solar cells, imaging applications, sensors, light detectors, biochemical applications, etc.