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Net energy gain in direct laser acceleration due to enhanced dephasing induced by an applied magnetic field
摘要： Even in the situation where an electron interacts with a single plane wave, the well-known dynamical adiabaticity can be broken when an applied magnetic field is present, which will act to increase the dephasing rate of the electron during the interaction. Here we demonstrate this for the case where there is a uniform static magnetic field which is oriented either parallel or perpendicular to the electric field of the incident plane wave, and perpendicular to the direction of its propagation. The described energy gain phenomenon has direct relevance to laser-plasma interactions that involve external magnetic fields generated by laser-driven capacitor coils.
关键词： net energy gain,direct laser acceleration,magnetic field,laser-plasma interactions,dephasing
更新于2025-09-19 17:13:59
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Magnetic field effect on the slow relaxation of photoconductance in tunnel coupled quantum dot arrays
摘要： The effect of magnetic field on the long-term photoconductance relaxation in two-dimensional arrays of Ge tunnel-coupled quantum dots grown on Si by molecular-beam epitaxy is studied. It was shown that the relaxation process can be slowed down as well as accelerated by magnetic field. The sign of changing the relaxation rate depends on the localization radius and the quantum dot occupancy. To explain an unusual acceleration effect we proposed a model based on the difference in probabilities of carrier transitions to single- or double-occupied quantum dots due to Zeeman effect.
关键词： Quantum dots,Photoconductance relaxation,Magnetic field,Zeeman effect
更新于2025-09-19 17:13:59
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Laser polishing of tool steel using a continuous-wave laser assisted by a steady magnetic field
摘要： Continuous-wave (CW) lasers are widely used in laser polishing, but with CW laser polishing, it is difficult to reduce the surface roughness to 0.2 μm from an original value exceeding 1.0 μm. The aim of this study is to develop an innovative method of laser polishing assisted by a steady magnetic field to overcome that bottleneck and produce smoother surfaces. Two experiments confirm the hypothesis that the molten pool overflows during melting peaks to flow into valleys in CW laser polishing, resulting in secondary roughness that causes the aforementioned quality bottleneck. To either reduce or eliminate this secondary roughness, a steady magnetic field is used during CW laser polishing to suppress the overflow of the molten pool. A three-dimensional surface profiler, a scanning electron microscope, and a nanometer indentation tester are used to characterize and analyze the microstructure and properties of the materials. The experimental results show that the Lorentz force due to the steady magnetic field plays an important suppression role in reducing the secondary roughness.
关键词： laser polishing,steady magnetic field,Lorentz force,molten pool overflow,continuous-wave laser,surface roughness
更新于2025-09-19 17:13:59
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Hidden Fine Structure of Quantum Defects Revealed by Single Carbon Nanotube Magneto-Photoluminescence
摘要： Organic color-center quantum defects in semiconducting carbon nanotube hosts are rapidly emerging as promising candidates for solid-state quantum information technologies. However, it is unclear whether these defect color-centers could support the spin or pseudo-spin dependent excitonic fine structure required for spin manipulation and readout. Here we conducted magneto-photoluminescence spectroscopy on individual organic color-centers and observed the emergence of fine structure states under an 8.5 T magnetic field applied parallel to the nanotube axis. One to five fine structure states emerge depending on the chirality of the nanotube host, nature of chemical functional group, and chemical binding configuration, presenting an exciting opportunity toward developing chemical control of magnetic brightening. We attribute these hidden excitonic fine structure states to field-induced mixing of singlet excitons trapped at sp3 defects and delocalized band-edge triplet excitons. These findings provide opportunities for using organic color-centers for spintronics, spin based quantum computing, and quantum sensing.
关键词： triplet,magnetic field,sp3 defect,photoluminescence,hybridization,carbon nanotubes
更新于2025-09-19 17:13:59
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Enhanced modulation of magnetic field on surface plasmon coupled emission (SPCE) by magnetic nanoparticles
摘要： The obvious enhancement effect of magnetic nanoparticles (MNPs) introduced in Cr/Co/Cr/Au substrate on the pulsed magnetic field-modulated surface plasmon coupled emission (SPCE) was investigated, and the observed enhancement factor was 4 comparing with the magnetic field modulated SPCE without MNPs. This is the new observation for the magnetic field-modulated SPCE in fluorescence signal and helps to build the new SPCE based stimulus-response system.
关键词： Magnetic field modulation,Magnetic nanoparticle,Surface plasmon coupled emission (SPCE),Fluorescence enhancement,Biosensor
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Novel Magnetometer Basedon Magnetic Fluid Coated Whispering Gallery ode Resonator
摘要： This paper presents an optical concept based on magnetic field fluid (MF)-coated microsphere for magnetic field detection. As refractive index (RI) of MF can be magnetically tuned under different applied magnetic fields, resonance shift of spherical whispering gallery mode (WGM) resonator is used as measurement principle. Preliminary experimental result demonstrates that a magnetic field strength sensitivity of 5.036pm/mT can be achieved using a 42um diameter of MF-coated microsphere with a Q-factor of 0.78×105.
关键词： Whispering gallery mode Resonator,Magnetic Fluid,Sensitivity,Fiber Taper,Magnetic Field
更新于2025-09-16 10:30:52
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Highly sensitive magnetic field sensor based on mode coupling effect in microstructured optical fibers
摘要： A highly sensitive magnetic field sensor based on mode coupling effect in a microstructured optical fiber (MOF) was theoretically investigated by using the finite element method. Magnetic fluid with refractive index higher than silica was designed to be filled into one cladding air hole in MOF to form a defect core. The coupling wavelength between fiber core modes and defect core modes can be modulated by external magnetic field. Simulation results show that the measuring sensitivity of magnetic field and figure of merit reached 1620? pm/Oe, 0.081/Oe in x-polarized mode and 1790? pm/Oe, 0.045/Oe in y-polarized mode, respectively. Meanwhile, the intensity of magnetic field depicts a good linear relationship with the coupling wavelength for both orthogonal polarized directions in the range of 25–175.9 Oe. The performance of the designed magnetic field sensor can be improved by optimizing the structural parameters in MOF.
关键词： Microstructured optical fiber,Mode coupling,Magnetic field sensor,Magnetic fluid
更新于2025-09-16 10:30:52
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The transition from double to single quantum dot induced by THz laser field
摘要： The combined influence of an intense laser field and a homogeneous magnetic field is considered on laterally coupled double quantum dot with isotropic and anisotropic parabolic confinement. It is shown that intense laser field can recover typical properties to a single quantum dot: it creates Fock–Darwin states in a double quantum dot with anisotropic confinement. Also, the laser and the magnetic field effects on the intraband absorption spectrum reveal blueshift if the laser field is increased and redshift with the gain of the magnetic field.
关键词： Double quantum dot,Fock–Darwin states,Intense laser field,Magnetic field,Intraband absorption
更新于2025-09-16 10:30:52
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Temporal Evolution of Polarization Resolved Laser-Induced Breakdown Spectroscopy of Cu
摘要： Polarization-resolved laser-induced breakdown spectroscopy based on a temporal investigation of polarized Cu plasma emission is presented by a gated detector with a width of 10 ns and a delay time range of 10 ns–2 μs. Polarization-resolved spectra show that the delay time plays a crucial role in plasma polarization for both continuum and discrete emissions. The polarization degree of continuum emission is shown to be stronger than the polarization degree of discrete emissions at delay times less than 500 ns, while this trend is inverse in a delay time range of 750 ns–1 μs. The mechanism for polarized continuum emission is proposed to have dynamic polarizability of a core, while the polarized discrete emission is driven by the interaction of the plasma with the surrounding environment. The latter may lead either to a deviation of plasma from local thermodynamic equilibrium or generation of self-magnetic fields.
关键词： Polarization-resolved laser-induced breakdown spectroscopy,Polarization,Laser-induced breakdown spectroscopy,Local temperature equilibrium,Self-generated magnetic field
更新于2025-09-16 10:30:52
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Laser-Produced Magnetic-Rayleigh-Taylor Unstable Plasma Slabs in a 20?T Magnetic Field
摘要： Magnetized laser-produced plasmas are central to many novel laboratory astrophysics and inertial confinement fusion studies, as well as in industrial applications. Here we provide the first complete description of the three-dimensional dynamics of a laser-driven plasma plume expanding in a 20 T transverse magnetic field. The plasma is collimated by the magnetic field into a slender, rapidly elongating slab, whose plasma-vacuum interface is unstable to the growth of the 'classical,' fluidlike magnetized Rayleigh-Taylor instability.
关键词： plasma dynamics,magnetic field,Rayleigh-Taylor instability,laser-produced plasmas
更新于2025-09-16 10:30:52