- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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A Gain-Enhanced Tri-Band Microstrip Square Antenna with Consistent Radiation Patterns by Manipulating its Higher-Order Modes
摘要： A gain-enhanced tri-band microstrip antenna using higher-order modes was analyzed and designed in this communication. It firstly proved in theory that by manipulating the equivalent magnetic currents' (EMCS) relative magnitudes, the higher-order modes' radiation patterns could be converted from conical to broadside. Their zenithal directivities would therefore greatly increase. The relationships between the EMCS' relative magnitudes and the directivities were studied. Then, those analyses were applied to design a gain-enhanced tri-band microstrip antenna using three higher-order modes. A simpler one-port differential feeding and several shorting pins and slots were used to control the antenna's EMCS to improve its radiation patterns. They could further increase the antenna's gains, suppress its side-lobe levels (SLLs) and cross-polarizations. The proposed antenna worked at 3.9 GHz, 4.95 GHz, and 5.9 GHz with consistent broadside radiation patterns and the same polarization. Their measured gains were about 10.0 dBi, 10.4 dBi, and 10.2 dBi, respectively.
关键词： gain-enhanced,microstrip antenna,slot,equivalent magnetic currents,shorting pins,higher-order modes
更新于2025-09-23 15:22:29
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Beam phase retrieval based on higher order modes in cylindrical superconducting radio frequency cavities
摘要： The control of beam phase relative to the accelerating RF field within a superconducting cavity is important in many accelerator applications and is of particular importance for a free electron laser facility. As standard practice, the phase is usually inferred from the beam-induced transient field with respect to a timing reference. We report here on an alternative and novel means of beam phase determination based on beam-excited higher order electromagnetic modes and the accelerating electromagnetic mode, which are conveniently available from the same coupler. The monopole modes are immune to the electron beam offset and therefore are best suited for the task. A coupled circuit model is used to assist the development and to rapidly assess the facility of the method. Simulations based on the circuit model indicate that the resolution of this system depends critically on the signal to noise ratio. Beam-based measurements with a test setup were carried out at the European X-ray Free Electron Laser (XFEL), Germany. Based on this new method, we have routinely obtained a resolution of 0.1°. The best resolution observed with the current setup was 0.03°. These results agree very well with the predictions from those predicted by a circuit model. The system investigated here can be used to provide diagnostic information for the current low level RF system employed in the European XFEL. To this end, the associated electronics are under development. This monitor is the first of its kind that can deliver direct and online measurements of the beam phase with respect to the RF field.
关键词： higher order modes,accelerator applications,beam phase retrieval,free electron laser,superconducting radio frequency cavities
更新于2025-09-23 15:21:21
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Harmonic Characterizations of Loaded Resonators for Waveguide Filters
摘要： A new method of controlling and predicting the harmonic responses, for spurious-free window improvement of millimeter-wave bandpass filters, with complete mathematical derivation, is presented in this paper. This method relies on loading a transmission line resonator with inverters, permitting the increase/ decrease of the harmonics-to-fundamental ratios, for predetermined inverter coupling values. It is a universal method based on circuit models and mathematical theories, independent of the fabrication implementation; only typical bandpass filter inverters are necessary. It does not affect or include the design of input/ output resonator ports, with materials and dimensions, introducing the least design complexity, cf. other earlier approaches. Resonators and bandpass filters using substrate integrated waveguide technology are designed, simulated, fabricated, measured and validated. The derived models, simulations and measured results are in good agreement. The control of the harmonic performance is demonstrated by comparing the measurements of two bandpass filters fabricated with-waveguides, in the millimeter-wave band 27.9 to 29.5 GHz. The inverter-loaded resonators, is analyzed versus a conventional iris filter operating with the TE10 mode. The comparisons of the simulations and measurements of the two filters demonstrate experimentally the possibility of the systematic control of the harmonics-to-fundamental ratios of the proposed theoretical analysis.
关键词： harmonic suppression,substrate integrated waveguide,Filters,higher-order modes,millimeter-wave,waveguide
更新于2025-09-23 15:21:01
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New Silica Laser-Optimized Multimode Optical Fibers with Extremely Enlarged 100-??m Core Diameter for Gigabit Onboard and Industrial Networks
摘要： We present new type of silica graded index laser-optimized multimode optical fibers (LOMF) with extremely enlarged core diameter up to 100 μm and “typical” “telecommunication” cladding diameter 125 μm. This optical fiber was designed for harsh environment Gigabit onboard cable systems and industrial networks. It differs by special optimized graded refractive index profile, providing low differential mode delay (DMD) for selected guided modes. We present some results of tests, performed for manufactured pilot 520 m length of described LOMF 100/125, concerned with its geometry properties as well as key transmission parameters—attenuation and DMD map.
关键词： mode coupling,laser-based gigabit data transmission,higher-order modes,large core multimode optical fiber,differential mode delay,short-range optical networks,industrial networks,selected guided modes,on-board cable systems,few-mode regime
更新于2025-09-23 15:19:57
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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) - Laser-Driven Semiconductor Switch as a Diagnostic Method in Terahertz Band
摘要： We present a full wave, large-signal analysis of a waveguide-embedded frequency multiplier array, solving the entire geometry using FEM EM modeling and including every nonlinear element in a Harmonic Balance simulation. The full 3D model employed provides the exact field distribution across the array, thus enabling us to account for substrate resonances, higher order mode excitation, instabilities, and diode yield. The model is compared with measurements on a 247 GHz fixed tuned 72-diode HBV tripler. In this example, higher order mode excitation was found due to the interaction between the filter and the diode array. This can only be observed using a full 3D model, which more accurately predicts the output power versus input power and frequency. Finally, the pros and cons of a full 3D model and a unit cell model for waveguide embedded multiplier arrays are discussed.
关键词： unit cell modeling,varactors,higher order modes,Frequency multipliers,spatial power combining,heterostructure barrier varactors
更新于2025-09-19 17:13:59
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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) - A sensitivity enhanced Sagnac temperature sensor utilizing high order modes interference
摘要： A temperature sensor is proposed by splicing a section of thin polarization-maintaining fiber in a Sagnac loop. The temperature sensitivity is enhanced by higher-order modes interference and reaches up to 1.7 nm/(cid:31).
关键词： Thin polarization-maintaining fiber,Temperature sensor,higher-order modes interference,Sagnac loop
更新于2025-09-16 10:30:52
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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) - Continuum Generation in Higher-Order Modes of Photonic Crystal Fibers
摘要： Low-noise supercontinuum (SC) generation in photonic crystal ?bers (PCFs) can be achieved by using pump pulses of femtosecond (fs) duration and low soliton numbers [1]. The small cores sizes needed to obtain anomalous dispersion for pump wavelengths in the Yb gain band (typically 1030-1070 nm) implies a severe restriction on power for such pump pulses. One possible strategy for power scaling is to pump in higher-order ?ber modes, which can attain the desired dispersion properties in larger cores. This contribution aims to explore the properties of such continua, in particular the conditions necessary to retain a single-mode character of the output.
关键词： nonlinear mode coupling,photonic crystal fibers,higher-order modes,supercontinuum generation
更新于2025-09-16 10:30:52
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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) - Third Harmonic Generation with Ultrashort Pulses in a C <sub/>2</sub> Cl <sub/>4</sub> Filled Liquid Core Fiber
摘要： Currently third harmonic generation (THG) in fibers is in focus of research, due to the prospects of enabling efficient generation of entangled photon triplets via the inverse, but spontaneous process. To date, microstructured and tapered fibers are the most prominent platforms to provide the high index contrast between the core and cladding material necessary to enable phase-matching (PM) to higher order modes (HOMs). Here, we employ a liquid core fiber (LCF) combining a silica cladding and a highly nonlinear core material, which can be temperature-tuned during operation [1]. We report the first experimental demonstration of THG in a liquid-core step-index-fiber formed by a silica capillary and a C2Cl4 filled core (Fig. 1b). The core liquid provides an enhanced electronic nonlinear coefficient compared to silica [2] and the LCF was designed to be single mode at the pump wavelength (1.55 μm). The modal dispersion of the fiber is engineered such that two HOMs at the TH wavelength are phase-matched within the spectrum of the ultrashort pump pulses, see Fig. 1a. An optofluidic mount is used for retaining, filling and launching pulses into the LCF. The LCF is pumped with 30 fs (Fig.1c) and 100 fs (Fig.1d) pulses (Toptica FemtoFiber pro IR and IRS-II, both at 80 MHz repetition rate). After filtering residual pump light the TH spectra are recorded for increasing power using a spectrum analyzer (Ando AQ6315A). The experimental results are shown in Fig.1c and d. In either case two distinct spectral peaks are visible in the TH corresponding to the two phase-matched HOMs. The images above Fig. 1d show the imaged output employing narrow bandpass filters, confirming the existence of individual modes. Comparing the efficiency for both pump pulses, the THG onset occurs at higher powers and the overall conversion is reduced for the shorter pulses. The high normal dispersion at the pump limits the effective conversion length due to dispersive pulse broadening. In conclusion, the capability of LCF for THG was demonstrated and future research towards quantum light generation in LCF can be envisioned.
关键词： liquid core fiber,higher order modes,phase-matching,ultrashort pulses,third harmonic generation
更新于2025-09-12 10:27:22
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In-line ports feeding substrate integrated waveguide resonator with higher order modes suppression
摘要： In-line ports are usually used to feed substrate integrated waveguide (SIW) resonator in an in-line transmission circuit. However, the higher order mode TE102 is excited as well as the fundamental mode TE101 thereby deteriorating the selectivity. Here the authors present a method to remove the selectivity deterioration. By additionally introducing TE201, the TE102 and the TE201 can be counteracted with each other by taking advantage of their out-phase out-coupling, and then both modes are suppressed well in a SIW resonator feeding with in-line ports. Two prototypes based on square and rectangle cavity are fabricated, respectively and measured to verify the proposed technique. The results agree with the expectation well. It shows the potential to be implemented in the in-line transmission circuit with SIW resonator.
关键词： resonator,higher order modes suppression,in-line ports,Substrate integrated waveguide
更新于2025-09-12 10:27:22
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[IEEE 2019 Systems of Signals Generating and Processing in the Field of on Board Communications - Moscow, Russia (2019.3.20-2019.3.21)] 2019 Systems of Signals Generating and Processing in the Field of on Board Communications - Simulation-Based Prediction of 100-μm-Core Multimode Optical Fiber Bandwidth for 10GBase-LX Systems
摘要： This work is concerned with application of earlier on developed an alternative method for simulation of piecewise regular multimode fiber optic links operating in a few-mode regime for computation of laser-excited optical pulse dynamics during its propagation over irregular silica graded- index multimode optical fibers (MMFs) with extremely large core diameter. Proposed model is based on the piecewise regular representation, and it takes into account launching conditions, differential mode delay, both lower- and higher- order mode chromatic dispersion, differential mode attenuation, mode mixing and power diffusion occurring due to real fiber irregularity and micro- and macro-bends. We present some results of simulation 10GBase-LX optical signal transmission over 100-μm-core MMFs graded-index refractive index profile corresponding to the typical laser-optimized MMFs 50/125 of ISO/IEC Cat. OM2+/OM3 scaled up to 100 μm core.
关键词： higher- order modes,few-mode regime,on-board cable systems,mode coupling,laser-based multi-Gigabit data transmission,large core multimode optical fiber,industrial networks,differential mode delay
更新于2025-09-11 14:15:04