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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Terahertz Emission from an Asymmetric Dual-Grating-Gate InGaAs High-Electron-Mobility Transistor Stimulated by Plasmonic Boom Instability
摘要： Asymmetric dual-grating-gate InGaAs high-electron-mobility transistors (ADGG-HEMTs) are studied as plasmonic terahertz (THz) emitters. We experimentally observed THz emission from a fabricated device at 110K. The spectra showed a broadband resonant emission under low d.c. channel currents reflecting radiation decay of thermally excited plasmons. With increasing the current and longitudinal electric field the emission was enhanced in a narrower spectral range suggesting promotion of plasmonic instability. Its threshold behavior suggests the occurrence of plasmonic-boom-type instability.
关键词： terahertz emission,plasmonic instability,asymmetric dual-grating-gate,high-electron-mobility transistors,InGaAs
更新于2025-09-16 10:30:52
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Resonance Instability of Photovoltaic E-Bike Charging Stations: Control Parameters Analysis, Modeling and Experiment
摘要： This article presents an in-situ comparative analysis and power quality tests of a newly developed photovoltaic charging system for e-bikes. The various control methods of the inverter are modeled and a single-phase grid-connected inverter is tested under different conditions. Models are constituted for two current control methods; the proportional resonance and the synchronous rotating frames. In order to determine the influence of the control parameters, the system is analyzed analytically in the time domain as well as in the frequency domain by simulation. The tests indicated the resonance instability of the photovoltaic inverter. The passivity impedance-based stability criterion is applied in order to analyze the phenomenon of resonance instability. In conclusion, the phase-locked loop (PLL) bandwidth and control parameters of the current loop have a major effect on the output admittance of the inverter, which should be adjusted to make the system stable.
关键词： grid-connected inverter,photovoltaic,solar mobility,resonance instability,power quality,solar charging
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
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Asymmetric magnetic reconnection driven by ultraintense femtosecond lasers
摘要： Three-dimensional asymmetric magnetic reconnection (AMR) driven by ultraintense femtosecond (fs) lasers is investigated by relativistic particle-in-cell (PIC) simulation. The reconnection rate is found to be only one-third of that in the previous symmetric reconnection PIC simulations. Similar to the case of dayside reconnection at geomagnetopause, magnetic X- and velocity stagnation points are not colocated, with the X-point at the lower ?eld side and the stagnation point at the higher ?eld side. Moreover, the moving direction of the X-point as reconnection evolving with the laser irradiation is determined by dBH=dBL, and the moving of stagnation point is dominated by neHBL=neLBH, where dB and ne are the magnetic ?eld disturbance and the electron density with the subscripts “H” for the higher ?eld side and “L” for the lower ?eld side, respectively. Then, the hosing instability triggered by AMR and the merging of two parallel currents resulting in the tilt of the electron beam generated by the weak laser are also investigated.
关键词： hosing instability,particle-in-cell simulation,reconnection rate,ultraintense femtosecond lasers,asymmetric magnetic reconnection
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) - Application of ultra-stable laser in coherent optical frequency transfer
摘要： We demonstrate the effect of utralstable laser in the high-precision coherent phase transfer of optical frequency. The ultra-stable laser with a linewidth of 0.68 Hz is applied for the optical frequency transfer over a 100 km-fiber link, achieving a transfer instability of 4.9× 10-17 at 100 s, which is about one order of magnitude superior than that with a 2.7 kHz linewidth laser, two times less than that with a 50 Hz linewidth laser. This indicates that the ultrastable lasers will play an important role in the optical frequency transfer.
关键词： utralstable laser,transfer instability,phase-coherent frequency transfer
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) - Optimization of Wide-Spectral Mode-Locking Fiber Laser Carriers in Free Space Optical Communication
摘要： We experimentally demonstrate an optimization of wide-spectral mode-locking fiber laser carriers by the introduction of two-pulse pump scheme with fiber dispersion management. We also verify the improved transmission performance of optimized wider-spectral carriers in 1km simulated atmospheric turbulent channel. For preferable compatibility and superiority, it can be an adaptive scheme for free space optical communication in the foreseeable future.
关键词： dispersion management,free space optical communication,Modulation instability
更新于2025-09-16 10:30:52
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Route from single-pulse to multi-pulse states in a mid-infrared soliton fiber laser
摘要： State-of-the-art ultrafast mid-IR ?ber lasers deliver optical solitons with durations of several hundred femtoseconds. The Er- or Ho-doped ?uoride gain ?bers generally used in these lasers have strong anomalous dispersion at ～3 μm, which generally forces them to operate in the soliton regime. Here we report that a pulse-energy clamping e?ect, caused by the buildup of intracavity nonlinearities, limits the shortest obtainable pulse durations in these mid-infrared soliton ?ber lasers. Excessive intra-cavity energy results in soliton instability, collapse and fragmentation into a variety of stable multi-pulse states, including phase-locked soliton molecules and harmonically mode-locked states. We report that the spectral evolution of the mid-IR laser pulses can be recorded between roundtrips through stretching their second-harmonic signal in a 25-km-length of single-mode ?ber. Using a modi?ed dispersive Fourier transform set-up, we were able to perform for the ?rst time spectro-temporal measurements of mid-IR laser pulses both in the pulsed state and during pulse collapse and fragmentation. The results provide insight into the complex nonlinear dynamics of mid-IR soliton ?ber lasers and open up new opportunities for obtaining a variety of stable multi-pulse mode-locked states at mid-IR wavelengths.
关键词： dispersive Fourier transform,soliton instability,multi-pulse states,pulse-energy clamping,mid-IR soliton ?ber lasers
更新于2025-09-16 10:30:52
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Breathers, multi-peak solitons, breather-to-soliton transitions and modulation instability of the variable-coefficient fourth-order nonlinear Schr?dinger system for an inhomogeneous optical fiber
摘要： Optical fiber communication system is one of the core supporting systems of the modern internet age. In this paper, under investigation is a variable-coefficient fourth-order nonlinear Schr?dinger system, which describes the simultaneous propagation of the optical pulses in an inhomogeneous optical fiber. The first-order breathers are constructed. Breathers are converted into several types of the nonlinear waves, i.e., multi-peak solitons, antidark solitons, periodic waves and W-shaped solitons, under the transition condition. With the decrease of |λr + a2|, the peak number of a multi-peak soliton increases, where λr represents the real part of the spectral parameter and a is a real constant. Peak number reaches the maximum since the multi-peak soliton is transformed into a set of the periodic waves with λr + a2 = 0. Widths and velocities of the multi-peak solitons are related to the group velocity dispersion and fourth-order dispersion coefficients. We find that the condition of baseband modulational instability coincides with the transition condition when we use the rogue-wave eigenvalues, i.e., the transition between the rogue waves and multi-peak solitons can occur in the baseband modulational instability.
关键词： Inhomogeneous optical fiber,Breathers,Multi-peak solitons,Modulation instability,Variable-coefficient fourth-order nonlinear Schr?dinger system
更新于2025-09-16 10:30:52
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Laser-cooled ytterbium-ion microwave frequency standard
摘要： We report on the development of a trapped-ion, microwave frequency standard based on the 12.6 GHz hyperfine transition in laser-cooled ytterbium-171 ions. The entire system fits into a 6U 19-in. rack unit (51 × 49 × 28 cm) and comprises laser, electronics, and physics package subsystems. As a first step towards a full evaluation of the system capability, we have measured the frequency instability of our system which is 3.6 × 10?12∕√?? for averaging times between 30 and 1500 s.
关键词： hyperfine transition,frequency instability,laser-cooled ytterbium-ion,microwave frequency standard
更新于2025-09-16 10:30:52
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Perovskite quantum dots for light-emitting devices
摘要： Perovskite quantum dots (QDs) have been hotly pursued in recent decades owing to their quantum confinement effect and defect-tolerant nature. Their unique optical properties, such as high photoluminescence quantum yield (PLQY) approaching unity, narrow emission bandwidth, tunable wavelength spanning the entire visible spectrum, and compatibility with flexible/stretchable electronics, render perovskite QDs promising for next-generation solid lighting sources and information displays. Herein, the advances in perovskite QDs and their applications in LEDs are reviewed. Strategies to fabricate efficient perovskite QDs and device configuration, including material composition design, synthetic methods, surface engineering, and device optimization, are investigated and highlighted. Moreover, the main challenges in perovskite QDs of instability and toxicity (lead-based) are identified, while the solutions undertaken with respect to composition engineering, device encapsulation, and lead-replacement QDs are demonstrated. Meanwhile, perspectives for the further development of perovskite QDs and corresponding LEDs are presented.
关键词： device encapsulation,quantum confinement,Perovskite quantum dots,LEDs,instability,composition engineering,flexible electronics,photoluminescence,lead-replacement,stretchable electronics,toxicity,light-emitting devices
更新于2025-09-16 10:30:52