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- 2019
- frequency noise
- quantum cascade laser
- optical feedback
- spectral linewidth
- photovoltaic power
- Cascade hydropower
- multi-energy hybrid power
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- renewable energy
- Optoelectronic Information Science and Engineering
- Electrical Engineering and Automation
- State Grid Sichuan Electric Power Research Institute
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- Tsinghua Sichuan Energy Internet Research Institute
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Design of High Temperature Superconducting Dual-Band Filter with Multiple Transmission Zeros
摘要： A multi-order dual-band high temperature superconducting (HTS) bandpass filter (BPF) with multiple transmission zeros (TZs) is designed in this paper. The theoretical characteristics of the introduction of TZs by the electric and magnetic mixed coupling, and the cascade quadruplet (CQ) cross-coupling structures are analyzed, respectively. These two methods can be applied to the design of the multi-mode compact dual-band HTS BPF with controllable central frequency, bandwidth and TZs. For demonstration, a Y-shape tunable resonator structure which can simultaneously implement the internal electric and magnetic mixed coupling, and the external cross coupling is constructed to achieve the proposed dual-band BPF. The external quality factors required by the two passbands and the feasibility of independently adjusting the coupling strength between adjacent resonators are analyzed. Finally, a 6-order dual-band HTS BPF with the center frequencies of 1490MHz (bandwidth of 40 MHz) and 2340MHz (bandwidth of 80 MHz) is designed and fabricated on the double-sided YBCO/MgO/YBCO HTS thin films with the size of 17.2mm×14.7mm (0.20λg × 0.17λg), and there are multiple of TZs located outside the two passbands, respectively. The out-of-band rejections are greatly improved to 70dB and 80dB due to these TZs, which fully exhibits the advantages of the proposed dual-band BPF. The measured results are in good agreement with the simulated ones.
关键词： high temperature superconducting (HTS),Dual-band,passband filter,transmission zero (TZ),cascade quadruplet (CQ)
更新于2025-09-23 15:23:52
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Dark current in long-wave cascade-transport infrared up-converters
摘要： Reducing the dark current in an infrared (IR) photodetector is one of the most important aspects in improving the detector’s performance. This article attempts to clarify the dominant paths of dark current and reduce it in a long-wave cascade-transport IR up-converter (CIUP), which has been reported to be a potential candidate for very-large-scale IR detection/imaging. The four paths of the dark current are considered, including the ground state sequential tunneling, thermionic emission onto the continuum, thermally-assisted transition onto the excited state of the absorption quantum well (QW) or some energy levels in the transport region. Accordingly three designs of the band structure are proposed for long-wave CIUPs, with miniband-to-miniband intersubband transition, bound-to-miniband transition and step-bound-to-miniband transition. Samples based on these designs are fabricated and measured. Both the calculated electron concentration distributions and the measured dark currents show that the step-bound-to-miniband structure is the most effective in cutting down the dark current, in which the superlattice barrier and InGaAs absorption QWs help to reduce dark current related to tunneling, thermionic emission and thermally-assisted tunneling.
关键词： Dark current,Up-converter,Step-bound-to-miniband,Long-wave infrared,Cascade
更新于2025-09-23 15:23:52
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Parameter optimization of cascade in quantum key distribution
摘要： Quantum key distribution (QKD) protocol mainly includes two stages: signal transmission stage based on quantum channel and post-processing stage based on classical channel, and the post-processing stage has gradually become a bottleneck restricting the high performance of QKD. Information reconciliation (IR) is a key step in post-processing. Cascade has been widely used in IR due to its excellent error correction performance. In this study, we analyze original Cascade and adjust parameters to improve the partition strategy. As a result, more errors are corrected under near-optimal conditions. We consider both reconciliation efficiency and frame error rate to measure protocol performance. Simulation shows that the improved Cascade can effectively improve the reconciliation efficiency while ensuring a small frame error rate. Overall, our improved Cascade has better performance on the final secret key rate.
关键词： Information reconciliation,Quantum key distribution,Cascade protocol
更新于2025-09-23 15:23:52
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Effect of monatomic and molecular ion irradiation on time resolved photoluminescence decay in GaN
摘要： Optical effects induced in silicon-doped wurtzite (0001) GaN epilayers by keV monatomic and molecular ion irradiation were experimentally investigated. Results were analyzed together with data on structure defect formation. In all the cases under consideration, an increase in the collision cascade density (the cases of molecular and heavy atomic ion bombardment) enhances the stable damage accumulation rate and, accordingly, intensifies quenching of luminescence. The processes of PL suppression were theoretically considered as an increase of surface recombination rate of nonequilibrium photo-excited charge carriers due to production of stable damage at the irradiated subsurface layer. It is shown that carrier diffusion determines PL decay time shortening in the shallow implantation cases studied.
关键词： Radiation damage,Photoluminescence,Collision cascade density,Time-resolved PL,Charge carrier diffusion,Ion implantation,GaN
更新于2025-09-23 15:23:52
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Learning to reconstruct shape and spatially-varying reflectance from a single image
摘要： Reconstructing shape and reflectance properties from images is a highly under-constrained problem, and has previously been addressed by using specialized hardware to capture calibrated data or by assuming known (or highly constrained) shape or reflectance. In contrast, we demonstrate that we can recover non-Lambertian, spatially-varying BRDFs and complex geometry belonging to any arbitrary shape class, from a single RGB image captured under a combination of unknown environment illumination and flash lighting. We achieve this by training a deep neural network to regress shape and reflectance from the image. Our network is able to address this problem because of three novel contributions: first, we build a large-scale dataset of procedurally generated shapes and real-world complex SVBRDFs that approximate real world appearance well. Second, single image inverse rendering requires reasoning at multiple scales, and we propose a cascade network structure that allows this in a tractable manner. Finally, we incorporate an in-network rendering layer that aids the reconstruction task by handling global illumination effects that are important for real-world scenes. Together, these contributions allow us to tackle the entire inverse rendering problem in a holistic manner and produce state-of-the-art results on both synthetic and real data.
关键词： rendering layer,global illumination,deep learning,SVBRDF,single image,flash light,cascade network
更新于2025-09-23 15:23:52
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Lignosulfonate: a Convenient FRET Platform for the Construction of Ratiometric Fluorescence pH-Sensing Probe
摘要： Lignin is a kind of natural fluorescent polymer material. However, the application based on the fluorescent property of lignin was rarely reported. Herein, a non-covalent lignin-based Fluorescence Resonance Energy Transfer (FRET) system was readily constructed by physical blending method with spirolactam Rhodamine B (SRhB) and lignosulfonate (LS) as the acceptor and donor groups, respectively. The FRET behavior, self-assembly and energy transfer mechanism of SRhB/LS composite were systematically studied. It was demonstrated that LS could be used as a convenient aptamer as energy donor to construct water-soluble ratiometric sensors because of its inherent property of intra-micelle energy transfer cascades. Our results not only presented a facile and general strategy for producing lignin-based functional material, but also provided a fundamental understanding about lignin fluorescent to promote the functional and high-valued applications of lignin fluorescence characteristic.
关键词： lignin,ratiometric sensor,FRET,intra-micelle energy transfer cascade
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - Fast SAW Device Simulation in COMSOL Using the Hierarchical Cascading Method
摘要： Using the hierarchical cascading method for modeling semiconductor devices makes it possible to achieve high accuracy by considering the influence of the details of the structure of the device. In this paper, we consider the simulation of a quantum cascade laser (QCL) with a periodic structure. The simulation is performed using the finite element method (FEM) in the COMSOL Multiphysics software. The results show that the proposed method allows to obtain the characteristics of the device with high accuracy.
关键词： finite element method,quantum cascade laser,COMSOL Multiphysics,simulation
更新于2025-09-23 15:23:52
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A unified figure of merit for interband and intersubband cascade devices
摘要： By exploring a semi-empirical model, the saturation current density J0 is identified to manifest the significant difference in carrier lifetime between interband cascade devices (ICDs) and intersubband quantum cascade devices (QCDs). Based on this model, the values of J0 have been extracted for a large number of ICDs and QCDs from their current-voltage characteristics at room temperature. By analyzing and comparing available ICD and QCD data, we demonstrate how J0 can be used as a unified figure of merit to evaluate both interband and intersubband cascade configurations for their device functionality. The significance of J0 on the performances of mid-infrared detectors and photovoltaic cells is illustrated by comparing the measured detectivity (D*) and the estimated open-circuit voltage (Voc), respectively. From extracted values of J0, which are more than one order of magnitude lower in ICDs than that in QCDs with similar transition energies in active regions, and discussion of the consequences on device performance, the advantages of interband cascade configurations over intersubband quantum cascade configurations have been clearly revealed based on the same framework. The overall picture for both QCDs and ICDs sheds light from the perspective of a united figure of merit, which will provide useful guidance and stimulation to the future development of both ICDs and QCDs.
关键词： Saturation current density,Interband cascade,Quantum cascade,Open-circuit voltage
更新于2025-09-23 15:22:29
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Performance Analysis of a Solar-Powered Multi-Effect Refrigeration System
摘要： The main objective of the current work is to investigate the thermodynamic performance of a novel solar powered multi-effect refrigeration system. The proposed cycle consists of a solar tower system with a heliostat field and central receiver (CR) that has molten salt as the heat transfer fluid, an absorption refrigeration cycle (ARC), an ejector refrigeration cycle (ERC), and a cascade refrigeration cycle (CRC). Energy and exergy analyses were carried out to measure the thermodynamic performance of the proposed cycle, using Dhahran weather data and operating conditions. The largest contribution to cycle irreversibility was found to be from the CR system (52.5%), followed by the heliostat field (25%). The first and second-law efficiencies improved due to the increase in the following parameters: ejector evaporator temperature, turbine inlet and exit pressures, and cascade evaporator temperature. Parametric analysis showed that the compressor delivery pressure, turbine inlet and exit pressures, hot molten salt outlet temperature, and ejector evaporator temperature significantly affect the refrigeration output.
关键词： triple effect,refrigeration,ejector,cascade,solar energy,absorption
更新于2025-09-23 15:22:29
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WaterSpy: A High Sensitivity, Portable Photonic Device for Pervasive Water Quality Analysis
摘要： In this paper, we present WaterSpy, a project developing an innovative, compact, cost-effective photonic device for pervasive water quality sensing, operating in the mid-IR spectral range. The approach combines the use of advanced Quantum Cascade Lasers (QCLs) employing the Vernier effect, used as light source, with novel, fibre-coupled, fast and sensitive Higher Operation Temperature (HOT) photodetectors, used as sensors. These will be complemented by optimised laser driving and detector electronics, laser modulation and signal conditioning technologies. The paper presents the WaterSpy concept, the requirements elicited, the preliminary architecture design of the device, the use cases in which it will be validated, while highlighting the innovative technologies that contribute to the advancement of the current state of the art.
关键词： Quantum Cascade Lasers,photonics,water quality monitoring,photodetectors
更新于2025-09-23 15:22:29