修车大队一品楼qm论坛51一品茶楼论坛,栖凤楼品茶全国楼凤app软件 ,栖凤阁全国论坛入口,广州百花丛bhc论坛杭州百花坊妃子阁

oe1(光电查) - 科学论文

过滤筛选

出版时间
  • 2018
研究主题
  • GaN HEMTs
  • Power amplifier
  • Broadband power amplifier
  • SC band
  • Power combining
  • concentrated capacitive load
  • distribution of the complex current at the antenna
  • broadband antenna
  • standing wave voltage factor
  • antenna gain factor
应用领域
  • Electronic Science and Technology
机构单位
  • Oles Honchar Dnipro National University
  • University of Tehran
  • Gdansk University of Technology
  • V. N. Karazin Kharkiv National University
  • Reykjavik University
244 条数据
?? 中文（中国） ▾

  • [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) - Numerical Investigation of Broadband OPCPA Configurations for Direct Amplification of TW-Level, Two-Cycle Pulses

    摘要： Generation of intense, isolated attosecond pulses is the main motivation for the development of laser systems which are producing few-cycle, TW-level pulses. The ELI-ALPS Single Cycle Laser (SYLOS) aims to provide 20 TW single cycle pulses at 1 kHz repetition rate. Due to the requirements for stability and high average power the most promising approach for generating mJ-level, few-cycle pulses is noncollinear optical parametric chirped pulse amplification (NOPCPA). BBO and LBO are the two most favoured nonlinear materials in the visible and near-infrared spectral range, due to their broad gain bandwidth and high damage threshold. It was demonstrated that BBO and LBO can support 5.5 fs and 7 fs pulse durations respectively when 450 nm and 515 nm pumping was used. Even shorter, sub-5 fs pulse durations can be achieved by utilizing two-color pumping, that is, the second- and third-harmonic of a Nd:YAG pump laser in subsequent amplifier stages. The latter solution is the most promising, however at 1 kHz repetition rate there is a risk of optics degradation due to high average power UV light. In this work, two alternative solutions were examined numerically for few-cycle pulse amplification. In the first one, single LBO crystal is used in a phase-matching configuration when the gain bandwidth supports 5 fs pulse duration. In the other solution, spectral multiplexing was utilized in a so-called BBO-sandwich configuration. The principle of the BBO-sandwich is that two thin BBO crystals packed close to each other with slightly different phase-matching angles, but the non-collinear angle between the signal and pump beams is the same in both crystals. As a result, a broader gain bandwidth can be achieved which can support 5 fs pulse duration. These broadband phase-matching configurations were numerically examined using an advanced 3D, OPCPA modelling software. The results of these simulations were well applicable either to rule out or to confirm certain configurations during the experimental development of ELI-ALPS SYLOS laser system. In most cases, the predicted total bandwidths were matched well with the experimental results, even when the spectrum shapes showed difference due to the model approximations. Numerical simulations predicts that the amplified spectrum supports 5 fs Fourier-limited duration and the spectral phase does not contain any fast oscillations thus the pulses are compressible to 5.5 fs. The output pulse energy is 50 mJ before pulse compression and the calculated Strehl-ratio is 0.77. The theoretical findings are also proved by the experimental results, which indicates that these phase-matching configuration are viable candidates for the production of TW-level, few-cycle pulses.

    关键词： TW-level pulses,few-cycle pulses,broadband OPCPA,noncollinear optical parametric chirped pulse amplification,LBO,BBO

    更新于2025-09-12 10:27:22

  • A Noble Metal Dichalcogenide for High‐Performance Field‐Effect Transistors and Broadband Photodetectors

    摘要： 2D layered materials are an emerging class of low-dimensional materials with unique physical and structural properties and extensive applications from novel nanoelectronics to multifunctional optoelectronics. However, the widely investigated 2D materials are strongly limited in high-performance electronics and ultrabroadband photodetectors by their intrinsic weaknesses. Exploring the new and narrow bandgap 2D materials is very imminent and fundamental. A narrow-bandgap noble metal dichalcogenide (PtS2) is demonstrated in this study. The few-layer PtS2 field-effect transistor exhibits excellent electronic mobility exceeding 62.5 cm2 V?1 s?1 and ultrahigh on/off ratio over 106 at room temperature. The temperature-dependent conductance and mobility of few-layer PtS2 transistors show a direct metal-to-insulator transition and carrier scattering mechanisms, respectively. Remarkably, 2D PtS2 photo detectors with broadband photodetection from visible to mid-infrared and a fast photoresponse time of 175 μs at 830 nm illumination for the first time are obtained at room temperature. Our work opens an avenue for 2D noble-metal dichalcogenides to be applied in high-performance electronic and mid-infrared optoelectronic devices.

    关键词： broadband photodetection,PtS2,on-off ratio,field-effect transistors,mobility

    更新于2025-09-12 10:27:22

  • Broadband visible-near infrared and deep ultraviolet generation by four-wave mixing and high-order stimulated Raman scattering from the hybrid metasurfaces of plasmonic nanoantennae and Raman-active nanoparticles

    摘要： The efficient generation of a broadband frequency comb from the visible to ultraviolet region is a challenging task despite its importance for nanoscale spectroscopy and sensing applications. In this paper, we reported broadband visible-near infrared and deep ultraviolet generation by four-wave mixing and high-order stimulated Raman scattering from hybrid metasurfaces made of plasmonic nanoantennae embedded with Raman-active diamond nanoparticles as examples. Upon two-color near-infrared pumping tuned to a Raman resonance, one can generate a visible-near infrared frequency comb with a major contribution of high-order stimulated Raman scattering by the coherent modulation of the Raman medium and simultaneously, a broad deep ultraviolet frequency comb is radiated by four-wave mixing and third-harmonic generations. The efficiencies of the individual spectral peaks reached values in the order of 10?8–10?2% under pumping with pulses with a peak intensity of about 33 GW cm?2 and a duration of 100 fs in the near infrared region.

    关键词： high-order stimulated Raman scattering,visible-near infrared,hybrid metasurfaces,plasmonic nanoantennae,Raman-active diamond nanoparticles,deep ultraviolet,broadband frequency comb,four-wave mixing

    更新于2025-09-12 10:27:22

  • Design and Fabrication of Dual-Scale Broadband Antireflective Structures on Metal Surfaces by Using Nanosecond and Femtosecond Lasers

    摘要： Antire?ective surfaces, with their great potential applications, have attracted tremendous attention and have been the subject of extensive research in recent years. However, due to the signi?cant optical impedance mismatch between a metal surface and free space, it is still a challenging issue to realize ultralow re?ectance on a metal surface. To address this issue, we propose a two-step strategy for constructing antire?ective structures on a Ti-6Al-4V (TC4) surface using nanosecond and femtosecond pulsed lasers in combination. By controlling the parameters of the nanosecond laser, microgrooves are ?rst scratched on the TC4 surface to reduce the interface re?ection. Then, the femtosecond laser is focused onto the sample surface with orthogonal scanning to induce deep air holes and nanoscale structures, which e?ectively enhances the broadband absorption. The antire?ection mechanism of the dual-scale structures is discussed regarding morphological characterization and hemispherical re?ectance measurements. Finally, the modi?ed sample surface covered with micro-nano hybrid structures is characterized by an average re?ectance of 3.1% over the wavelengths ranging from 250 nm to 2250 nm.

    关键词： nanosecond laser,broadband spectrum,femtosecond laser,micro-nano hybrid structures,antire?ective surfaces

    更新于2025-09-12 10:27:22

  • [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) - UV-Grade Silica-Based Photonic Crystal Fibers for Broadband UV Generation over 350–395 nm

    摘要： A major challenge in supercontinuum (SC) generation is to overcome the shortcomings of existing fibre-based SC sources in the ultraviolet (UV) wavelength range below 400 nm. There is particular need for broadband sources of UV light in applications such as multi-photon fluorescence microscopy for simultaneous coherent excitation of multiple fluorophores. However, UV generation in conventional silica-core fibres is extremely difficult because of factors such as material absorption, large normal dispersion, glass stability, power handling, and aging, and this has motivated much recent interest in the use of alternative approaches. Although these results show great promise, compatibility with the ubiquitous silica platform remains a problem, and there is thus intense current interest in generating UV-light using modified UV-resistant silica glasses. In this paper, we report the design and fabrication of small-core highly nonlinear UV-grade photonic crystal fiber (PCF) drawn from Heraeus F110 UV-resistant silica glass, and its application to broadband UV generation over 260-400 nm. The few mode PCF is shown in Fig. 1(a) and was designed with: core diameter ~4.24 μm, hole diameter d = 3.5 μm, pitch Λ =3.88 μm, and was designed to support five LP modes in a scalar approximation. The calculated dispersion coefficients and mode profiles are shown in Figs 1(b) and (c). Figure 1(d) and (e) show experimental results pumping with picosecond laser pulses at 355 nm. For a 1m length of the PCF, we observe intermodal four-wave mixing (FWM) peaks with Fig. 1(d) showing a series of spectra as the output power varies from 0.1 – 0.2 mW. The FWM peaks are generated over the range 350-370 nm and the peak positions are in good agreement with calculations based on the fibre modal characteristics. For a longer 3 m fibre length, intermodal FWM is not observed, but rather we see cascaded Raman scattering out to 6th-order over the range 355-395 nm. The UV-emission was observed to have stable 0.3 mW output power without any detrimental photo-darkening. In this paper, we have reported the fabrication of highly nonlinear photonic crystal fiber from UV-grade glass and experimentally demonstrate nonlinear frequency conversion over 350-395 nm by pumping at 355 nm with picosecond laser pulses. These results represent an important step towards efficient UV supercontinuum generation in an all-silica fiber platform.

    关键词： nonlinear frequency conversion,broadband UV generation,supercontinuum generation,UV-grade silica-based photonic crystal fibers,UV-resistant silica glass

    更新于2025-09-12 10:27:22

  • Super absorption of solar energy using a plasmonic nanoparticle based CdTe solar cell

    摘要： Improving the photon absorption in thin-film solar cells with plasmonic nanoparticles is essential for the realization of extremely efficient cells with substantial cost reduction. Here, a comprehensive study of solar energy enhancement in a cadmium telluride (CdTe) thin-film solar cell based on the simple design of a square array of plasmonic titanium nanoparticles, has been reported. The excitation of localized plasmons in the metallic nanostructures together with the antireflection coating (ARC) significantly enhances the absorption of photons in the active CdTe layer. The proposed structure attained super absorption with a mean absorbance of more than 97.27% covering a wide range from visible to near-infrared (i.e., from 300 nm to 1200 nm), presenting a 90% absorption bandwidth over 900 nm, and the peak absorption is up to 99.9%. For qualitative analysis, the photocurrent density is also estimated for AM 1.5 solar illumination (global tilt), whose value reaches 40.36 mA cm?2, indicating the highest value reported to date. The impact of nanoparticle dimensions, various metal materials, shapes, and random arrangement of nanoparticles on optical absorption are discussed in detail. Moreover, the angle insensitivity is essentially validated by examining the absorption performance with oblique incidences and it is found that the solar cell keeps high absorption efficiency even when the incidence angle is greater than 0°. Therefore, these findings suggest that the proposed broadband structure has good prospect in attaining high power conversion efficiency while reducing the device cost.

    关键词： photocurrent density,titanium nanoparticles,plasmonic nanoparticles,broadband absorption,CdTe solar cell

    更新于2025-09-12 10:27:22

  • [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) - Broadband Infrared (2.7–20 μm) Generation Via Random Quasi-Phase-Matched Intra-Pulse Difference-Frequency Generation

    摘要： Coherent mid-infrared (MIR) light has a plethora of important applications ranging from life-science to industrial processes. Simultaneous coverage of this region will enable the parallel detection of various chemicals and enhance the specificity of their detection [1]. One of the most popular broadband infrared generation methods is nonlinear down-conversion from the near-infrared. An effective conversion can be achieved by using phase-matching and quasi-phase-matching in birefringent crystals and crystals with periodically poled structure respectively. Random quasi-phase-matching (RQPM) in poly-crystals is an alternative method that has recently shown great promise [2,3], which results in a gradual growth of the generated signal linear to the propagation length. Compared to generic phase-matching schemes, RQPM offers an unparalleled phase-matching bandwidth that is insensitive to incident angle. In addition, unlike single-crystals, poly-crystals can easily be grown into larger dimensions to enable longer interaction lengths. Here we describe the generation of octave-spanning MIR continuum at over 20 mW of average power based on RQPM driven by a Ho:YAG thin-disk oscillator at 2.1 μm [4]. To the best of our knowledge, this is the first time RQPM has been implemented for intra-pulse difference-frequency generation (DFG). A 1 μm laser system based on a Yb:YAG thin-disk oscillator [5] was also tested as the driving source in this scheme.

    关键词： ZnS,mid-infrared,Broadband infrared,random quasi-phase-matching,intra-pulse difference-frequency generation,ZnSe

    更新于2025-09-12 10:27:22

  • Broadband light emission induced by laser absorption and optimized by thermal injection in Nd <sup>3+</sup> :Y <sub/>2</sub> SiO <sub/>5</sub> ceramic powder

    摘要： Laser induced broadband (white) light emission has been studied in different particle systems for use in light emitting devices. The photoinduced phenomenon occurs above a certain excitation power threshold and it is generally studied under vacuum conditions. In this work, the phenomenon is studied in neodymium doped yttrium silicate ceramic powder synthesized by combustion method. White light is observed when the sample is excited in ambient air with a CW near-infrared (λ = 808 nm) laser powered above 1.3 W. When the temperature of the sample is externally raised above 200 oC, white light is observed above 1.0 W and a large enhancement of the broadband emission intensity is observed.

    关键词： broadband emission,up-conversion,neodymium doped yttrium silicate,laser induced,thermal injection

    更新于2025-09-11 14:15:04

  • Indium‐rich InGaN/GaN solar cells with improved performance due to plasmonic and dielectric nanogratings

    摘要： In this study, we propose an indium‐rich InGaN/GaN p‐i‐n thin‐film solar cell which incorporates a dual nanograting (NG) structure: Ag nanogratings (Ag‐NGs) on the backside of the solar cell and gallium nitride nanogratings (GaN‐NGs) on the frontside. Finite‐difference time‐domain (FDTD) simulation results show that the dual NG structure couples the incident sunlight to the plasmonic and photonic modes, thereby increasing the absorption of the solar cell in a broad spectral range. It is observed that the solar cells having the dual nanograting structures have a significant enhancement in light absorption as compared to cells having either no nanogratings or having only the frontside nanogratings or only the backside nanogratings. Analysis of light absorption in solar cells containing the dual NG structures showed that the absorption enhancement of longer wavelengths is mostly due to the Ag‐NGs on the backside and of shorter wavelengths is mostly due to the GaN‐NGs on frontside of the solar cell. The Jsc and power conversion efficiency (PCE) are calculated under AM1.5G solar illumination and are observed to be significantly enhanced due to the presence of optimized dual NG structures. While there is an increase in Jsc from 17.88 to 23.19 mA/cm2 (~30% enhancement), there is an increase in PCE from 15.49% to 20.24% (~31% enhancement) under unpolarized light (average of TM and TE). Moreover, the study of oblique light incidence shows significantly larger Jsc of the dual nanograting solar cells compared to the cells with no nanogratings.

    关键词： broadband absorption,FDTD simulations,light trapping,surface plasmons,nanogratings,InGaN solar cells

    更新于2025-09-11 14:15:04

  • Configurable triple wavelength semiconductor optical amplifier fiber laser using multiple broadband mirrors

    摘要： A configurable, triple wavelength fiber laser based on broadband mirrors (BBMs) and an arrayed waveguide grating (AWG) is demonstrated. The laser uses a semiconductor optical amplifier (SOA) as the primary gain medium due to its inhomogeneous broadening property that allows for the generation high intensity lasing wavelengths. The combination of the AWG and BBMs allows for triple lasing wavelength outputs with channel spacing from 0.8 to 4.0 nm to be obtained. The generated output is adjustable between 1540.6 and 1548.6 nm. The proposed SOA-based system is stable and can be used as a reserve laser source for wavelength division multiplexing systems.

    关键词： multi-wavelength,SOA,AWG,WDM,broadband mirror

    更新于2025-09-11 14:15:04