- 标题
- 摘要
- 关键词
- 实验方案
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Effect of second-order nonlinearity on quantum coherent oscillations in a quantum dot embedded in a doubly resonant-semiconductor micro-cavity
摘要： The quantum Rabi oscillations in a coherently driven quantum dot embedded in a high-Q doubly resonant semiconductor micro-cavity in the presence of a strong second-order nonlinear medium is investigated theoretically. It is shown that the χ(2) nonlinearity effect the Rabi oscillations in a significant manner.
关键词： Rabi oscillation,Semiconductor microcavity,Second order nonlinearity
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Xi'an, China (2019.6.3-2019.6.6)] 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - A New Single-Phase Single-Stage Photovoltaic Grid-Tied Inverter with Leakage Current Eliminating and Power Decoupling
摘要： Common-mode leakage current and double-line-frequency power oscillation are two major challenges of non-isolated single-phase grid-tied inverters. To overcome these two challenges, this paper proposes a new single-phase single-stage inverter for photovoltaic grid-tied systems, which consist of two switches, three capacitors, two inductors, and one diode. The proposed topology allows the negative pole of the photovoltaic panel to be directly connected to the neutral line of the utility grid so that the common-mode leakage current is eliminated completely. Then a mixed modulation strategy combining pulse width modulation and pulse frequency modulation is proposed to suppress the double-line-frequency power oscillation. Two of the capacitors are utilized to handle the power difference between the AC and DC sides, and the other is utilized to implement zero voltage switching. The proposed inverter is also capable of outputting reactive power. The validity of the proposed inverter is veri?ed by simulation.
关键词： zero voltage switching,double-line-frequency power oscillation,grid-tied inverter,common-mode leakage current,mixed modulation strategy
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Xi'an, China (2019.6.3-2019.6.6)] 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - An Extraction Method for the Parasitic Capacitance of the Photovoltaic Module Based on the Oscillation of the Leakage Current
摘要： In photovoltaic (PV) plant, the parasitic capacitance between the PV module and the ground causes leakage current in the non-isolated systems. The case can be deteriorated in the rain environment, because increases dramatically due to the rain water. This paper presents an extraction method for the parasitic capacitance between the PV module and the ground. Unlike the common analytical, numerical way and direct measurement method, the parasitic capacitance is obtained through measurement of the leakage current oscillation. A full-bridge inverter is used to explain the principle as well as for the measurement. Theoretical calculation, MATLAB simulations and experimental measurements finally verify the accuracy of the proposed methods. The experimental results are shown to validate the method works well.
关键词： photovoltaic module,parasitic capacitance,leakage current,oscillation
更新于2025-09-11 14:15:04
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Chemoplasmonic Oscillation: A Chemomechanical Energy Transducer
摘要： Chemical oscillations and waves are nonequilibrium systems that sustain a steady state with constant energy input of reactants like the life systems. Most of these oscillations are theoretically and fundamentally exploited but how to mimic the energy convolution of biological systems remains elusive. Here we develop a chemomechanical energy transducer (CoMET) based on gold nanoparticles (Au NPs) and thermo-/pH-responsive polymers, which transforms the trapped chemical energy into a tangible mechanical oscillation probed by extinction spectra. Our results show that the mechanical movement of Au NPs characterized by the chemoplasmonic oscillation follows exactly the pH oscillation and can be tuned by changing the temperature and the injection rate of the reductants. It is revealed that the energy input of the redox potentials which later converts to the collective (dis-)aggregation of Au NPs is the main driving force of the chemoplasmonic oscillation. The energy efficiency (～34%) and force generation (～28 pN) of this CoMET outperforms many biochemomechanical systems, which offers an alternative means to power the nanomechanics and nanomachines.
关键词： energy,pH,extinction,chemical oscillation,plasmons
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Degenerate Mirrorless Optical Parametric Oscillator
摘要： A mirrorless optical parametric oscillator (MOPO) is a very special class of optical parametric oscillators, where the feedback for oscillation is realized by counter-propagating second-order nonlinear interaction without a need for external mirrors. This arrangement makes the MOPO a very simple, self-aligned and robust oscillator. The MOPO was first proposed theoretically in 1966 [1] however its realization was only possible using the quasi-phase matching (QPM) approach due to requirement for compensation of large momentum mismatch in such interactions [2]. Realization of first-order counter-propagating parametric oscillation requires structures with periodicity in the sub-μm range, which poses substantial fabrication challenges. In addition to its self-aligned nature, MOPO offers unique spectral properties [3], whereby the spectral contents of the pump are transferred to the forward wave, while the backward wave remains narrowband. So far, only nondegenerate MOPO oscillation has been demonstrated. However, it has been theoretically proposed that a degenerate MOPO could be used to realize a high-brightness biphoton source for quantum optics applications [4]. In this work we report on the first realization of the degenerate MOPO generating counter-propagating signal and idler in the spectral band of optical communications. The MOPO was realized in periodically poled Rb-doped KTiOPO4 (PPRKTP) with a QPM period of 420 nm. The structure was fabricated by the coercive field engineering technique [5]. First, the crystals were patterned using a UV laser interference lithography. Then a coercive field grating was created by periodic ion-exchange. Finally, the crystals were poled using planar electrodes. The resulting domain pattern shows excellent uniformity over the whole crystal aperture, and a duty cycle close to 50% (see Fig 1(a)). The optical surfaces of the crystals were polished at an angle to prevent Fresnel-reflection feedback into the MOPO.
关键词： degenerate MOPO,Rb-doped KTiOPO4,mirrorless optical parametric oscillator,counter-propagating parametric oscillation,quasi-phase matching
更新于2025-09-11 14:15:04
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A Bouc–Wen Model-Based Compensation of the Frequency-Dependent Hysteresis of a Piezoelectric Actuator Exhibiting Odd Harmonic Oscillation
摘要： This paper proposes an enhancement of the Bouc–Wen hysteresis model to capture the frequency-dependent hysteretic behavior of a thin bimorph-type piezoelectric actuator which also exhibits odd harmonic oscillation (OHO) at specific input frequencies. The odd harmonic repetitive controller has recently been proposed to compensate for the hysteresis, and attenuates the OHO of the piezoelectric actuator for which the hysteresis nonlinearity is regarded as a disturbance. This paper proposes an alternate treatment of the hysteresis compensation with the attenuation of the OHO observed at some input frequencies. It will be shown that the proposed compensator fully utilizes the mathematical structure of the enhanced Bouc–Wen model proposed in this paper to compensate the hysteresis and to attenuate the OHO. The results of the hysteresis compensation experiment illustrate the excellent performance of the proposed control system, especially at the frequencies where OHO is conspicuous.
关键词： Bouc–Wen model,hysteresis compensation,hysteresis modeling,odd harmonic oscillation,piezoelectric actuator
更新于2025-09-11 14:15:04
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Interband and intraband transition, dynamical polarization and screening of the monolayer and bilayer silicene in low-energy tight-binding model
摘要： We investigate the interband and intraband transitions of the monolayer and AB-stacked bilayer silicene in low-energy tight-binding model under the electric ?eld, where we focus on the dynamical polarization function, screening due to the charged impurity, and the plasmon dispersion. We obtain the logarithmically divergent polarization function within the random-phase-approximation, whose logarithmic singularities correspond to the discontinuities of the ?rst derivative at momentum q ? 2kF in static case and indicates the topological phase transition point between the gapless semimetal and the gapped band insulator. We also obtain the power-law-dependent Friedel oscillation which can be enhanced by increasing the Rashba coupling. The Friedel oscillation contributes to the screened potential of the charged impurity which scale as (cid:2) r(cid:3)1=2 in short distance from the impurity and scale as (cid:2) r(cid:3)1=3 in long distance from the impurity. In single-particle excitation regime with electron–hole continuum, the interband and intraband transitions happen, and the plasmon dispersion starts to damped into the electron–hole pairs due to the nonzero imaginary part of the polarization function. We also observe the linear (weakly damped) plasmon model for the classical bilayer silicene which is similar to the high-energy p-plasmon or the case of conducting substrate which with strong metallic screening. The density dependence of the plasmon dispersion is also clari?ed in this paper. Our results can also be applied to the other low-energy Dirac models or the topological insulators.
关键词： Friedel oscillation,Collective plasmon model,Silicene,Dynamical polarization,Screened potential
更新于2025-09-10 09:29:36
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Influence of temperature on the oscillations of longitudinal magnetoresistance in semiconductors with a nonparabolic dispersion law
摘要： The density of energy states were obtained in a quantizing magnetic ?eld at different temperature and for nonquadratic dispersion law. The dependence of the density of energy states on temperature in quantizing magnetic ?elds is studied with the nonquadratic dispersion law. The continuous spectrum of the energy density of states at low temperature is transformed into discrete Landau levels. The theory of the temperature dependence of the oscillation Shubnikov–de Haas in semiconductors with a nonparabolic dispersion law is constructed, taking into account the thermal broadening of the Landau levels. The cyclotron effective mass of the electrons is determined from the Shubnikov–de Haas data. The theoretical results are compared with experimental data in Bi1.99Tl0.01Se3.
关键词： Nonparabolic dispersion law,Longitudinal magnetoresistance,Landau levels,Cyclotron effective mass,The density of states,Oscillation Shubnikov–de Haas
更新于2025-09-10 09:29:36
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Double carrier transport in electron-doped region in black phosphorus FET
摘要： Double carrier transport has been observed in thin film black phosphorus (BP) field effect transistor devices in the highly electron-doped region. BP thin films with a typical thickness of 15 nm were encapsulated by hexagonal boron nitride thin films to avoid degradation by air exposure. Their Hall mobility reached 5300 cm2/V s and 5400 cm2/V s at 4.2 K in the hole- and electron-doped regions, respectively. The gate voltage dependence of conductivity exhibits an anomalous shoulder structure in the electron-doped region. In addition, at gate voltages above the shoulder, the magnetoresistance changes to positive, and there appears an additional slow Shubnikov-de Haas oscillation. These results strongly suggest the appearance of second carriers, which originate from the second subband with a localized band edge.
关键词： black phosphorus,Shubnikov-de Haas oscillation,double carrier transport,electron-doped region,field effect transistor
更新于2025-09-10 09:29:36
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The natural oscillations in stratospheric ozone observed by the GROMOS microwave radiometer at the NDACC station Bern
摘要： A multilinear parametric regression analysis was performed to assess the seasonal and inter-annual variations of stratospheric ozone profiles from the GROMOS (GROund-based Millimeter-wave Ozone Spectrometer) microwave radiometer at Bern, Switzerland (46.95?N, 7.44?E, 577 m). GROMOS takes part in the Network for the Detection of Atmospheric Composition Change (NDACC). The study covers the stratosphere from 50 to 0.5 hPa (from 21 to 53 km) and extends over the period from January 1997 to January 2015. The natural variability was fitted during the regression analysis through the annual and semi-annual oscillations (AO, SAO), the quasi-biennial oscillation (QBO), the El Ni?o–Southern Oscillation (ENSO) and the solar activity cycle. Seasonal ozone variations mainly appear as an annual cycle in the middle and upper stratosphere and a semi-annual cycle in the upper stratosphere. Regarding the inter-annual variations, they are primarily present in the lower and middle stratosphere. In the lower and middle stratosphere ozone variations are controlled predominantly by transport processes, due to the long lifetime of ozone whereas in the upper stratosphere its lifetime is relatively short and ozone is controlled mainly by photochemistry. The present study shows agreement in the observed naturally induced ozone signatures with other studies. Further, we present an overview of the possible causes of the effects observed in stratospheric ozone due to natural oscillations at a northern mid-latitude station. For instance regarding the SAO, we find that polar winter stratopause warmings contribute to the strength of this oscillation since these temperature enhancements lead to a reduction in upper stratospheric ozone. We have detected a strong peak amplitude of about 5% for the solar cycle in lower stratospheric ozone for our 1.5 cycles of solar activity. Though the 11-year ozone oscillation above Bern is in phase with the solar cycle, we suppose that the strong amplitude is partly due to meteorological disturbances and associated ozone anomalies in the Northern hemisphere. Further, our observational study gave the result that ozone above Bern is anti-correlated to the ENSO phenomenon in the lower stratosphere and correlated in the middle stratosphere.
关键词： solar activity cycle,annual oscillation,Switzerland,stratospheric ozone,NDACC,GROMOS,El Ni?o–Southern Oscillation,Bern,semi-annual oscillation,quasi-biennial oscillation,natural oscillations
更新于2025-09-09 09:28:46