- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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High power all-fiberized and narrow-bandwidth MOPA system by tandem pumping strategy for thermally induced mode instability suppression
摘要： An all-?berized and narrow-bandwidth master oscillator power ampli?cation (MOPA) system with record output power of 4 kW level and slope ef?ciency of 78% is demonstrated. Tandem pumping strategy is tentatively introduced into the narrow-bandwidth MOPA system for thermally induced mode instability (TMI) suppression. The stimulated Brillouin scattering (SBS) effect is balanced by simply using one-stage phase modulation technique. With different phase modulation signals, SBS limited output powers of 336 W, 1.2 kW and 3.94 kW are respectively achieved with spectral bandwidths accounting for 90% power of ～0.025, 0.17 and ～0.89 nm. Compared with our previous 976 nm pumping system, TMI threshold is overall boosted to be >5 times in which tandem pumping increases the TMI threshold of >3 times. The beam quality (M 2 factor) of the output laser is well within 1.5 below the TMI threshold while it is ultimately saturated to be 1.86 with the in?uence of TMI at maximal output power. Except for SBS and TMI, stimulated Raman scattering (SRS) effect will be another challenge for further power scaling. In such a high power MOPA system, multi-detrimental effects (SBS, SRS and TMI) will coexist and may be mutual-coupled, which could provide a well platform for further comprehensively investigating and optimizing the high power, narrow-bandwidth ?ber ampli?ers.
关键词： optimization,design,laser ampli?ers,narrow linewidth,high power laser,laser systems,modeling,advanced laser technology and applications,?ber laser and applications
更新于2025-09-10 09:29:36
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First Experimental Demonstration and Mechanism of Abnormal Palladium Diffusion Induced by Excess Interstitial Ge
摘要： This letter represents the ?rst direct experimental demonstrations and mechanism proposal regarding abnormal palladium diffusion into germanium (Ge). Our experiments indicated that excess Ge atoms among palladium germanide alloy formation indirectly induce the abnormal out-diffusion of mass palladium atoms into Ge. Consequently, palladium germanide alloy on both n-type and p-type Ge form ohmic-like Schottky junctions. To identify this phenomenon, ?rst-principle calculations and technology computer-aided design simulation were used to evaluate the electrical in?uence of palladium atoms in Ge. We discovered that the activated palladium atoms in Ge induce large midgap bulk-trap states, which contribute to a severe increment of trap-assisted tunneling current at the palladium germanide/Ge junction.
关键词： Schottky junction,First-principles calculations,palladium germanide,technology computer-aided design,germanium,trap-assisted tunneling,fermi-level pinning effect
更新于2025-09-10 09:29:36
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Adjoint method and inverse design for nonlinear nanophotonic devices
摘要： The development of inverse design, where computational optimization techniques are used to design devices based on certain specifications, has led to the discovery of many compact, non-intuitive structures with superior performance. Among various methods, large-scale, gradient-based optimization techniques have been one of the most important ways to design a structure containing a vast number of degrees of freedom. These techniques are made possible by the adjoint method, in which the gradient of an objective function with respect to all design degrees of freedom can be computed using only two full-field simulations. However, this approach has so far mostly been applied to linear photonic devices. Here, we present an extension of this method to modeling nonlinear devices in the frequency domain, with the nonlinear response directly included in the gradient computation. As illustrations, we use the method to devise compact photonic switches in a Kerr nonlinear material, in which low-power and high-power pulses are routed in different directions. Our technique may lead to the development of novel compact nonlinear photonic devices.
关键词： nanophotonics,Inverse design,integrated photonics,optical switching,nonlinear optics
更新于2025-09-10 09:29:36
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Controlling the Solder Joint Reliability of eWLB Packages in Automotive Radar Applications Using a Design for Reliability Approach
摘要： A DfR (Design for Reliability) approach which is systematically based on simulation, sensitivity analysis and experimental validation is applied for identifying, understanding and controlling the key factors which determine the solder joint reliability of eWLB (Embedded Wafer Level Ball Grid Array) packages that carry embedded 77 GHz dies and sit on hybrid PCB (Printed Circuit Board) stacks. The hybrid stack investigated in this work is characteristic to automotive RADAR (Radio Detection And Ranging) applications and consists of one low-loss RF (Radio Frequency) layer and several FR4 layers. In line with previous work [1], the mechanical material properties of the low-loss RF laminate material are found to be the key factor. Simulation is used to systematically screen for mechanical properties which are favorable for achieving a high solder joint reliability on the unconstrained PCBs used for standardized solder joint reliability testing. A simplified virtual assessment of PCBs constrained by the mounting in system module housings is done. Both simulation and experimental results show that RF laminate materials with low Young’s modulus are the class of materials which allows for the highest solder joint reliability for all the conditions investigated in this study.
关键词： RF laminate,Design for Reliability,eWLB,solder joint reliability,automotive RADAR
更新于2025-09-10 09:29:36
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Research on and design of key circuits in RFID tag chip for container management
摘要： This paper introduces the design of semi-passive RFID tag chip capable of monitoring container safety. A system framework complying with requirements by ISO/IEC 18000-6C is firstly presented, and then differences from the key units of common passive chip, such as switch-state monitoring circuit, power management unit and anti-shake design in baseband processor, are elaborated. The main function of such a chip is to record the container opening frequency during transportation. Finally, the realizations of each unit’s function are simulated.
关键词： anti-shake design,tag chip,power management,switch-state monitoring,RFID,container management
更新于2025-09-10 09:29:36
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Improved design of a photon enhanced thermionic energy converter
摘要： In this work, the model of photon enhanced thermionic energy converter (PETEC) is improved to design a new vacuum thermionic energy converter (VTEC) consisting of a cathode and an anode is established, in which the two electrode materials are made of p-type silicon semiconductor coated negative electron affinity material and boron doped diamond. Formulas for the power output density and efficiency of the VTEC are derived. The electron affinity is optimized to obtain the maximum power output density and efficiency of the VTEC. Making a trade-off between the power output density and efficiency, the parametric optimum design criteria are determined. The results obtained in this work are helpful for developing novel VTECs.
关键词： Electron affinity,Work function,Optimum design,Finite time thermodynamics,Thermionic emission
更新于2025-09-09 09:28:46
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Design and development of in-situ temperature dependent diffuse reflectance spectroscopy setup
摘要： Recent advancements in the commercialization of In-situ temperature dependent optical spectrophotometer have shown potential not only for the recording of optical absorption spectra but also towards the exploration of physical insights and the understanding of instrument handling. Measurement on the effect of the variation of temperature onto optical properties mainly for semi-conducting oxides helps to explore the functioning and play a crucial role towards the development of optoelectronic devices. Being a non-contact, non-destructive technique temperature dependent DRS Setup can be used as a primary tool for the in-situ characterization of optical properties. This appreciation prompts us to design and develop an instrument that can add the ability of in-situ temperature dependent DRS above room temperature. The setup, developed and reported here, is able to accurately characterize the samples from room temperature to 500 K, which is most suitable range for the characterization of semiconducting materials, which is in the heard of current materials’ research. The present study provides the economical alternatives to the existing designs used for this purpose without compromising on the reliability of the obtained data. The in-house developed set up is found to be efficiently used for the analysis of various properties of the samples and will open up the instrumental development and commercialization of the temperature dependent DRS technique.
关键词： Detection of defects,Photon detectors for UV, visible and IR photons (solid-state),Overall mechanics design (support structures and materials, vibration analysis etc),Spectrometers
更新于2025-09-09 09:28:46
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Hard limits on the postselectability of optical graph states
摘要： Coherent control of large entangled graph states enables a wide variety of quantum information processing tasks, including error-corrected quantum computation. The linear optical approach offers excellent control and coherence, but today most photon sources and entangling gates—required for the construction of large graph states—are probabilistic and rely on postselection. In this work, we provide proofs and heuristics to aid experimental design using postselection. We introduce a versatile design rule for postselectable experiments: drawn as a graph, with qubit as vertices and gates and photon-pair sources as edges, an experiment may only contain cycles with an odd number of sources. We analyse experiments that use photons from postselected photon-pair sources, and lower bound the number of accessible classes of graph state entanglement in the non-degenerate case—graph state entanglement classes that contain a tree are are always accessible. The proportion of graph states accessible by postselection shrinks rapidly, however. We list accessible classes for various resource states up to 9 qubits. Finally, we apply these methods to near-term multi-photon experiments.
关键词： photon sources,entanglement,graph states,linear optical quantum computing,postselection,numerical methods,photonic experiment design
更新于2025-09-09 09:28:46
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A novel surface roughness measurement method based on the red and green aliasing effect
摘要： A common requirement in many machine learning algorithms is that the training data is sufficient. However, in the visual measurement of surface roughness, this requirement often can't be meet due to the reason that it is time-consuming and expensive to process and label the training samples. To address this issue, this paper proposes a novel method to establish an advanced roughness predictive model with less standard training samples based on inductive transfer learning. The experimental results show that the proposed method has superior measurement performance, and can maintain the average relative error of 12.57% even when the training data is insufficient. This indicates that the proposed method can provide a new strategy for improving the visual roughness measurement performance.
关键词： Roughness measurement,Index design,Inductive transfer learning,Machine vision
更新于2025-09-09 09:28:46
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A cm-Scale 2.4-GHz Wireless Energy Harvester With NanoWatt Boost Converter and Antenna- Rectifier Resonance for WiFi Powering of Sensor Nodes
摘要： The widespread use of WiFi in the 2.4-GHz ISM band creates the potential for RF powering using WiFi radios. This paper presents the design of a cm-scale RF-energy harvester including antenna, rectifier, and dc–dc boost converter for RF powering in the 2.4-GHz ISM band. The rectifier and boost converter are designed while considering cold-start operation and nanowatt-scale available power from the rectifier for RF incident power <?33 dBm. Low-power design in the power management unit and converter leads to ～1-nW quiescent power. The harvester implementation in 65-nm CMOS occupies 1.6 mm2 while the antenna occupies 1.27 cm2. The proposed design optimization approach leads to a sensitivity of ?33 dBm in cold start and ?36 dBm in the primary mode for 1-V output, translating to ～1.4× and ～2× improvement in range compared to prior art. Measurements using a commercial WiFi TX demonstrate the ranges of up to 1.25 m for 14-dBm output power with 1.3% TX duty-cycling in WiFi access-point mode, demonstrating the feasibility of powering sensors from RF power beacons in the 2.4-GHz ISM band as well as from background WiFi transmissions.
关键词： wireless powering,co-design,Antenna,ultralow power,WiFi charging,power management,sensitivity,boost converter,rectifier,RF,cold start,energy harvesting
更新于2025-09-09 09:28:46