- 标题
- 摘要
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- 实验方案
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Mode-locked All-fiber Laser Emitting Two-color High-order Transverse Mode
摘要： We demonstrate that the mode-locked all-?ber laser can simultaneously emit two-color broadband LP11 transverse mode in the near-infrared region by sharing a common mode-selective coupler (MSC). The MSC mode converter is designed to achieve simultaneous dual-channel mode conversion corresponding to the wavelength regions at 1.0 (cid:22)m and 1.5 (cid:22)m, in which each channel possesses broadband mode conversion from LP01 to LP11 mode with high mode purity. As a proof of concept, we implement an all-?ber ytterbium (Yb) and erbium (Er) doped ?ber lasers with mode-locked two-color LP11 modal output. The laser consists of two ring cavities combined with a common MSC mode converter. The generated LP11 modal pulses have a full width at half maximum (FWHM) of 11 nm and 8.1 nm for Yb- and Er-doped ?ber laser (YDFL and EDFL), respectively. The presented ?ber laser would represent a promising light source in the ?eld of structured light and ultrafast optics.
关键词： Two-color,mode-locking,MSC,dual-channel mode conversion
更新于2025-11-28 14:24:03
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[IEEE 2018 International Symposium on Electromagnetic Compatibility (EMC EUROPE) - Amsterdam (2018.8.27-2018.8.30)] 2018 International Symposium on Electromagnetic Compatibility (EMC EUROPE) - Investigation on Degradation of Common Mode Noise Suppression with Electrostatic Discharge Protection Array
摘要： In this paper, it is proposed that the electrostatic discharge protection devices may degrade the common-mode noise suppression. The mode conversion of ESD protection devices for single and multiple differential transmission lines are investigated. Experiments are set up to measure the scattering parameters and common-mode current of common-mode filter cascading different ESD protection devices. From the experimental results, the cases with four-line ESD protection array perform worse mode conversion and common-mode noise suppression.
关键词： mode conversion,common-mode noise suppression,high-speed input/output interface,electrostatic discharge
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - Cartagena des Indias, Colombia (2018.9.10-2018.9.14)] 2018 International Conference on Electromagnetics in Advanced Applications (ICEAA) - EM Wave Scattering by a Window on a Wall
摘要： Electromagnetic wave scattering by a window on a building wall has been analyzed here as plane wave scattering by a dielectric slab in a thick conducting screen. High frequency asymptotic ray method is utilized for this analysis. Geometrical Theory of Diffraction has been used to obtain the diffracted fields by the edges of the aperture, then ray-mode conversion technique has been applied to get the modal field inside the slit region in order to consider the modal coupling and the re-radiation field. The validity of our formulation has been first tested by comparing the results with those obtained by the Kobayashi Potential method for the relatively narrow slit aperture cases. Then the various numerical calculation results have been made to show the effects of the wall and window thickness, and window’s glasses for practical wireless mobile communication frequencies.
关键词： ray-mode conversion,GTD,EM scattering,thick slit,window
更新于2025-09-23 15:21:21
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Single-cycle THz signal accompanying laser wake in photoionized plasmas
摘要： Photoionization of an ambient gas by a weakly relativistic, femtosecond laser pulse leaves behind the pulse a ?at-top plasma column. The uniform-density core of the column is surrounded by a micron-thin shell, within which the density of plasma species falls down to zero. As the laser pulse ponderomotive force drives the wave of charge separation (the laser wake), electron ?uid velocity oscillates along this boundary layer. Coupling velocity oscillations to the transverse density gradient forms an azimuthally polarized rotational current con?ned within the boundary layer. At each radial offset, this current oscillates with a local (THz-scale) Langmuir frequency, transforming the cylindrical electrostatic plasma wave into a radially evanescent Fourier component of an electromagnetic signal. Summing up these Fourier components yields the time-domain THz signal which is (a) non-local (i.e. not phase-locked to the Langmuir oscillation at any given location), (b) contains the entire frequency band from zero to the Langmuir frequency of the density plateau, and (c) is detectable at a distance orders of magnitude larger than the plasma column radius. A few millimeters away from the column, rapid evanescence of the higher-frequency components transforms the signal into a radially polarized, single-cycle picosecond pulse with a kV m?1-scale electric ?eld. Detecting this pulse with existing (e.g. electro-optical) techniques may bring information on the ef?ciency of laser coupling to the plasma, the amplitude of wake ?elds, and the structure of the column boundary.
关键词： electromagnetic mode conversion,optical ?eld ionization,THz pulse,laser wake?eld
更新于2025-09-23 15:19:57
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Mode Conversion Based on Lateral Misalignment between Two Multi-Ring Core Fibers for MDM System
摘要： In this report, mode conversion based on the lateral misalignment between two similar multi-ring core fibers (M-RCFs) is proposed. The conversion was achieved by varying the lateral height (y) and the distance (x) that separates the two M-RCFs. Based on the achieved coupled power of 94%, this technique may find application as a conversion device during multiplexing in mode-division multiplexed systems (MDM).
关键词： coupled power,multi-ring core,mode conversion,mode division multiplexing
更新于2025-09-19 17:15:36
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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) - Enhanced Magneto-Optical Effects in Magnetic Photonic Crystal Fiber Based on Yttrium Iron Garnet
摘要： In this paper, a kind of magnetic photonic crystal fiber of Yttrium iron garnet (YIG) is presented. The influence of gyrotropy on TE-TM mode conversion is analysed, which depends on Faraday rotation. The structure parameters are simulated and optimized. The optimum efficiency of 93.57% is obtained. Faraday rotation and modal birefringence have been calculated by varying gyrotropy from 0.01 to 0.04. The numerical results reveal an increased Faraday rotation and a reduced modal birefringence of 10-5. The enhanced properties of the structure could improve photonic devices performance, which make it suitable for magneto-optical isolators.
关键词： Modal birefringence,Faraday rotation,YIG,Magnetic photonic crystal fiber,Mode conversion
更新于2025-09-16 10:30:52
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The Critical Adiabatic Linear Tapered Waveguide Combined with a Multimode Waveguide Coupler on an SOI Chip
摘要： A multimode waveguide interference (MMI) coupler is combined with a critical linear tapered waveguide on a silicon-on-insulator (SOI) chip. When the TE0 mode is a critical adiabatic mode conversion from a single-mode waveguide to an extreme linear tapered waveguide combined with an MMI, this linear tapered waveguide is achieved to the maximum divergence angle (i.e., the shortest length). The maximum divergence angle is expressed by θ ≤ 2 tan? 1[(0.35Wmmi ? Ws)/(0.172Lmmi)] under a 1 × 1 MMI combined with this critical linear tapered waveguide. The expression formula is demonstrated by three di?erent widths of a 1 × 1 MMI of 4 μm/8 μm/12 μm combined with the critical linear tapered waveguide. So, the maximum divergence angle is obtained at θ ? 16°/14°/8°, with respect to this linear tapered waveguide loss of 0.022 dB/0.172 dB/0.158 dB, and this linear tapper length is reduced by 93.7%/92.9%/87.5% than the divergence angle θ ? 1°. The output power of a 1 × 1 MMI combined with a critical linear tapered waveguide is enhanced at least 1.5 times under 0.95 above condition.
关键词： multimode waveguide interference (MMI) coupler,TE0 mode,linear tapered waveguide,silicon-on-insulator (SOI) chip,adiabatic mode conversion
更新于2025-09-12 10:27:22
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Switchable multiwavelength thulium-doped fiber laser with cylindrical vector beam emission
摘要： We experimentally demonstrate a switchable multiwavelength thulium-doped fiber laser with cylindrical vector beam (CVB) emission, which is the first report, to our best knowledge, on the generation of CVBs in a 2 μm wavelength band. The Sagnac loop filter, made up of a 50:50 coupler, a section of polarization-maintaining fiber and a polarization controller, serves as a periodical filter and accounts for the excitation of multiwavelength channels. The mode-selective coupler consisting of both tapered single-mode and four-mode fibers has been designed and fabricated as a mode converter from LP01 to LP11 mode with a purity of >80%. By adjusting the polarization controllers, laser outputs with 1–3 switchable wavelengths have been realized in the spectrum ranging from 1988–1998 nm. The laser could find miscellaneous applications in wavelength/mode-division multiplexing system, etc.
关键词： cylindrical vector beams (CVBs),thulium-doped fiber laser (TDFL),multiwavelength fiber laser,mode conversion
更新于2025-09-12 10:27:22
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Selectivity Properties of Cylindrical Waveguides with Longitudinal Wall Corrugations for Second-Harmonic Gyrotrons
摘要： Spatial harmonic method is applied to investigate selectivity properties of longitudinally corrugated waveguides for potential application in second-harmonic gyrotrons. The effect of corrugations on frequencies, ohmic losses, and mode conversion of guiding TE modes is studied in details. Numerical results are presented for operating second-harmonic and competing first-harmonic modes of a 0.4-THz gyrotron with corrugated RF structure. It is shown that longitudinal wall corrugations of proper dimensions can ensure increase in ohmic losses and decrease in beam-wave coupling strength for the first-harmonic modes, while their effect on the operating mode is only slight. This demonstrates improved selectivity properties of corrugated waveguides for second-harmonic gyrotrons.
关键词： Ohmic losses,Gyrotron,Mode conversion,Cyclotron harmonic,Corrugated waveguide,Eigenvalue
更新于2025-09-11 14:15:04
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Plasma volume holograms for focusing and mode conversion of ultraintense laser pulses
摘要： Beating of a broad laser reference beam with a quite general focused object beam inside a plasma volume generates a dynamic plasma hologram. Both beams may be of moderate intensity. The volume hologram can be read out by an ultraintense main beam (of similar structure as the reference beam) producing an object beam replica. For the latter, intensity in the focus may become extremely large. As an application, the possibility of a read-out focused Gaussian laser pulse with intensity of several 1019 W/cm2 in focus is shown by three-dimensional numerical simulations. Besides the focusing possibility, the hologram may also act as a mode converter for high-intensity laser pulses. Generating a plasma hologram with a focused Laguerre-Gaussian object beam results in a staggered plasma density grating, allowing the production of high-intensity vortex beam replica.
关键词： ultraintense laser pulses,Laguerre-Gaussian beams,plasma volume holograms,focusing,mode conversion
更新于2025-09-11 14:15:04