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[IEEE 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Xiamen, China (2019.12.17-2019.12.20)] 2019 Photonics & Electromagnetics Research Symposium - Fall (PIERS - Fall) - Efficient Characterization of Topological Photonics Using the Broadband Greena??s Function
摘要： A novel method is developed in this paper to characterize the band diagram and modal ?elds of gyromagnetic photonic crystals that support topolgoical one-way edge states. We exploy an integral equation based method that utilizes the broadband Green’s function as the kernel. The broadband Green’s function is a hybrid representation of the periodic lattice Green’s function that includes an imaginary wavenumber component represented in exponentially decaying spatial series and a reminder in fast converging Floquet plane wave expansions. Special boundary conditions govern the ?elds across the interface of the gyromagnetic scatterers, leading to surface integral equations (SIEs) that involve three components including the pilot ?eld, its normal derivative and its tangential derivative. To reduce the independent number of unknowns, roof-top basis functions and the Garlerkin’s method are used to discretize the SIEs into matrix equations. The broadband Green’s function allows converting the discretized SIEs into a linear eigenvalue problem of a small size. The eigenvalues and eigenvectors of the linear eigenvalue problem are directly related to the band solutions and modal ?elds of the photonic crystal. The proposed approach is an e?ective method to characterize wave interactions with periodic scatterers using integral equations. The solutions of the presented approach are compared against Comsol simulations for various cases to show its accuracy and e?ciency.
关键词： topological photonics,surface integral equations,broadband Green’s function,linear eigenvalue problem,gyromagnetic photonic crystals
更新于2025-09-23 15:21:01
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Bandgap engineering in CuO nanostructures: Dual-band, broadband, and UV-C photodetectors
摘要： In this work, the bandgap of CuO (p-type semiconductor) has been engineered from an indirect bandgap of (cid:2)1 eV to a direct bandgap of 4 eV just by tuning the nanostructure morphology and midgap defect states. The absorption in near-infrared (NIR) and visible regions is ordinarily suppressed by controlling the growth parameters. Considering the increasing scope and demand of varying spectral range (UV-C to NIR) photodetectors, the systematic variation of the available density of states (DOS) at a particular energy level in CuO nanostructures has been utilized to fabricate dual-band (250 nm and 900 nm), broadband (250 nm–900 nm), and UV-C (250 nm) photodetectors. The sensitivity and detectivity of the photodetector for broadband detectors were (cid:2)103 and 2.24 (cid:3) 1011 Jones for the wavelengths of 900 nm and 122 and 2.74 (cid:3) 1010 Jones for 250 nm wavelength light, respectively. The UV-C detector showed a sensitivity of 1.8 and a detectivity of 4 (cid:3) 109 Jones for 250 nm wavelength light. A plausible mechanism for the photoconduction has been proposed for explaining the device operation and the effect of variation in available DOS. The obtained photodetectors are the potential candidates for future optoelectronic applications.
关键词： Broadband photodetectors,Bandgap engineering,CuO nanostructures,Dual-band photodetectors,UV-C photodetectors
更新于2025-09-23 15:21:01
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Surface Engineered Hybrid Corea??Shell Sia??Nanowires for Efficient and Stable Broadband Photodetectors
摘要： Silicon nanostructures have gained intensive interest to develop broadband photodetectors at a large-scale due to their excellent electronic properties. Herein, Si-nanowires (SiNWs) decorated with reduced graphene oxide:carbon quantum dots (rGO:CQDs) nanocomposite (NC), as core–shell heterojunction building blocks for broadband (ultraviolet (UV)–near infrared (NIR)) photodetectors (PDs), are demonstrated. The SiNWs and CQDs are synthesized by wet-chemical etching and facile pyrolysis methods, respectively. Photogenerated carriers are transported through rGO because of its high electron mobility and favorable band alignment with CQDs and Si. Further, to minimize the recombination of photogenerated carriers, and enhance the response in the visible region, plasmon-enhanced AuCQDs are incorporated in the shell matrix. The optimized heterostructure (rGO:AuCQDs/undoped CQDs/SiNWs) is sensitive to a broad wavelength range covering the UV to NIR (360 to 940 nm) region, manifests the excellent responsivity of 16 A W?1 at 360 nm, detectivity (D*) of 2.2 × 1013 Jones, and noise equivalent power as low as 2.8 fW Hz?1/2. The optimized PDs heterostructure demonstrates excellent air-stability after 8 days of illumination without any encapsulation or protective coating. The proposed simple, cost-effective, and Si-process-line compatible fabrication of Si-based PD device structure imposes a great promise for highly efficient and stable advanced futuristic optoelectronic devices.
关键词： core–shell heterostructure,detectivity,responsivity,broadband photodetectors,reduced graphene oxide,carbon quantum dots,Si nanowires
更新于2025-09-23 15:21:01
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Fe doped ZnO/BiVO4 heterostructure based large area, flexible, high performance broadband photodetector with ultrahigh quantum yield
摘要： Pristine ZnO has been widely explored for UV photodetectors; however it’s utility in broadband photodetectors is still an impediment due to absorbance in UV region only with low quantum efficiency and responsivity that can be accredited to high recombination rate of photo generated charge carriers. To address this issue, we report Fe metal doped 2D ZnO thin films through band gap engineering and 1D electrospun mixed inorganic monoclinic BiVO4 nanofibers heterostructure on ITO coated PET substrate based broadband photodetector (PD) with ultra-high responsivity and EQE values in comparison to PDs fabricated using expensive cleanroom techniques. BiVO4 plays the dual role of captivating photons in the visible and NIR regions and creating local electric fields at the interface of Fe doped ZnO (FZO)-BiVO4 heterostructure which helps in separation of electron-hole pairs. The robustness of the flexible PD was further examined under repeated conditions of bending cycles (upto 500) yielding stable response. The responsivity values obtained for UV, Visible and NIR lights are 7.35 A/W, 3.8 A/W and 0.18 A/W with very high EQE values of 2501.7 %, 851.2 % and 28.3 % respectively. The facile and cost-effective fabrication of the device with high performance gives a new approach for developing flexible electronics and high-performance optoelectronics devices.
关键词： Heterostructure,Broadband photodetector,Fe doped ZnO,BiVO4,ultrahigh quantum yield
更新于2025-09-23 15:21:01
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Development of a predictive capability of short-pulse laser-driven broadband x-ray radiography
摘要： High intensity, short-pulse laser interaction with a solid metal target produces broadband hard x rays potentially for various applications of x-ray radiography. Here experimental benchmarking of numerical modelling for short-pulse laser-driven broadband x-ray radiography is presented. Angular dependent x-ray spectra are first calculated with a hybrid particle-in-cell code, Large Scale Plasma (LSP), using fast electron parameters inferred from an analysis of measured bremsstrahlung signals. Subsequently, a calculated x-ray spectrum in the direction of radiography is used in photon transport calculations using a Monte Carlo code, Particle and Heavy Ion Transport code System (PHITS), to simulate a radiographic image including a modelled 3D test object, an x-ray attenuation filter and an image plate detector. Simulated radiographic images are compared with measurements obtained in an experiment using a 50-TW Leopard short-pulse laser at the University of Nevada Reno. Results show that simulations reproduce the experimental images well for three different attenuation filters (plastic, aluminium, and brass), while one-dimensional transmission profiles for the plastic and aluminium filters are quantitatively in good agreement. The modelling approach established in this work could be used as a predictive tool to simulate radiographic images of complex 3D solid objects at any arbitrary angular position or to optimize experimental components such as the source spectrum, x-ray attenuation filters and a detector type depending on a radiographic object without carrying out radiographic experiments.
关键词： Monte Carlo simulations,hybrid particle-in-cell,broadband x-ray radiography,short-pulse laser-produced x rays
更新于2025-09-23 15:21:01
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All organics thin film flexible photodetector based on C<sub>60</sub> modified PEDOT:PSS
摘要： In organic electronics, the use of self-assembled monolayer dielectric functional groups is considered an effective surface modification strategy that can significantly improve device performance. A flexible polymer (PEDOT:PSS) photodetector on the substrate polyimide (PI) with broadband response (450 nm~980 nm) and high response (0.56 A/W) is reported, which is superimposed on the surface by small molecule (C60) thermal evaporation. In addition, the planeness of organic semiconductor and the overall performance of organic thin film photodetector can be improved significantly by using small molecule modified polymer thin film, the response of small molecule modified organic device is improved by an order of magnitude, which provides a guarantee for better application of organic thin films in circuits. Moreover, the device has strong flexibility stability performance, which can meet the requirements of flexible stability of future photoelectric devices.
关键词： organic thin film,high responsivity,broadband response,Photodetector,flexibility
更新于2025-09-23 15:21:01
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Ultrasensitive Ambient-Stable SnSe<sub>2</sub>-based Broadband Photodetectors for Room-Temperature IR/THz Energy conversion and Imaging
摘要： The advent of tin diselenide (SnSe2) enables novel pathways for optoelectronics, due to its reduced cost, ultralow thermal conductivity and high potential for thermoelectricity. To date, SnSe2-based optoelectronic devices have been focused on the visible and infrared range of the electromagnetic spectrum, with efficiency sharply decreasing at longer wavelength. Here, we present SnSe2 photodetectors with exfoliated SnSe2 nanosheets extended in the range of THz frequency, exhibiting high responsivity (170 V W-1), fast speed(2.2 μs), as well as room-temperature operation, based on efficient production of hot electrons under deep-subwavelength electromagnetic focus, which outperform thermal-based photodetectors. The outstanding ambient stability of our broadband photodetectors in a timescale of months is due to the chemical inertness of stoichiometric SnSe2 crystals, validated by surface-science experiments. Our results demonstrate the suitability of SnSe2for multispectral sensing and real-time imaging. Our SnSe2-based detectors show high-contrast imaging from terahertz (THz) up to visible.
关键词： Photothermoelectric,Terahertz,Tin diselenide,Broadband photodetector
更新于2025-09-23 15:21:01
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High performance broadband photodetectors based on Sb2Te3/n-Si heterostructure
摘要： With the rapid development of optoelectronic devices, photodetectors have triggered an unprecedented promising in the field of optical communication, environmental monitoring, biological imaging, chemical sensing. At the same time, there is a higher requirement for photodetectors. It is still a huge challenge for photodetectors that possess excellent performance, low cost and broad range photoresponse from ultraviolet to infrared. In this work, a facile, low cost growth of Sb2Te3 thin film using magnetic sputtering was performed. After rapid annealing treatment, the crystallinity of the thin film was transformed from amorphous to polycrystalline. Ultraviolet-visible-infrared absorption study of the thin film revealed broad absorption range, which is ideal for use in broadband photodetectors. Such photodetectors can find many important applications in communication, data security, environmental monitoring and defense technology etc. A prototype photodetector, consisting of Sb2Te3/n-Si heterostructure, was produced and characterized. The device demonstrated a significant photoelectric response at a broad spectral range of between 250 and 2400 nm. The maximum responsivity and detectivity of the device were 270 A/W and 1.28×1013 Jones, respectively, under 2400 nm illumination. Therefore, the results showed the potential use of Sb2Te3 thin film in developing high performance broadband photodetectors.
关键词： photodetector,Sb2Te3,broadband
更新于2025-09-23 15:21:01
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[IEEE 2019 European Space Power Conference (ESPC) - Juan-les-Pins, France (2019.9.30-2019.10.4)] 2019 European Space Power Conference (ESPC) - Electrostatic Discharge Tests for JUICE Photovoltaic Assembly
摘要： A nominally circular 2-D broadband acoustic array of 1.3-m diameter, comprising 508 sensors and associated electronics, was designed, built, and tested for ambient noise imaging (ANI) potential in Singapore waters. The system, named Remotely Operated Mobile Ambient Noise Imaging System (ROMANIS), operates over 25–85 kHz, streaming real-time data at 1.6 Gb/s over a fiber optic link. By using sensors that are much larger than half-wavelength at the highest frequency of interest, so with some directionality, good beamforming performance is obtained with a small number of sensors compared to a conventional half-wavelength-spaced array. A data acquisition system consisting of eight single-board computers enables synchronous data collection from all 508 sensors. A dry-coupled neoprene cover is used to encapsulate the ceramic elements as an alternative to potting or oil filling, for easier maintenance. Beamforming is performed in real-time using parallel computing on a graphics processing unit (GPU). Experiments conducted in Singapore waters yielded images of underwater objects at much larger ranges and with better resolution than any previous ANI system. Although ROMANIS was designed for ANI, the array may be valuable in many other applications requiring a broadband underwater acoustic receiving array.
关键词： broadband array design,Ambient noise imaging (ANI),data acquisition,underwater acoustics
更新于2025-09-23 15:21:01
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Wafer-Scale Fabrication of 2D PtS <sub/>2</sub> /PtSe <sub/>2</sub> Heterojunctions for Efficient and Broadband Photodetection
摘要： The fabrication of van der Waals heterostructures have mainly extends to two-dimensional materials that are exfoliated from their bulk counterparts, which is greatly limited by high-volume manufacturing. Here, we demonstrate multilayered PtS2/PtSe2 heterojunctions covering a large area on SiO2/Si substrate with a maximum size of 2" in diameter, offering throughputs that can meet the practical application demand. Theoretical simulation was carried out to understand the electronic properties of the PtS2/PtSe2 heterojunctions. Zero-bias photoresponse in the heterojunctions is observed under laser illumination of different wavelengths (405 to 2200 nm). The PtS2/PtSe2 heterojunctions exhibit broadband photoresponse, high quantum efficiency at infrared wavelengths with lower bounds for the external quantum efficiencies (EQE) being 1.2% at 1064 nm, 0.2% at 1550 nm and 0.05% at 2200 nm, and also relatively fast response time at the dozens of millisecond level. The large area, broadband 2D heterojunction photodetector demonstrated in this work further corroborating the great potential of 2D materials in the future low-energy optoelectronics.
关键词： van der Waals heterostructures,self-driving operation,quantum efficiency,broadband photodetection,photoresponsivity,wafer-scale fabrication
更新于2025-09-23 15:21:01