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- 2018
- 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
- Electronic Science and Technology
- Oles Honchar Dnipro National University
- University of Tehran
- Gdansk University of Technology
- V. N. Karazin Kharkiv National University
- Reykjavik University
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High responsivity and fast UV-Vis-SWIR photodetector based on Cd3As2/MoS2 heterojunction
摘要： High responsivity, fast response time, ultra-wide detection spectrum are pursuing goals for state-of-art photodetectors. Cd3As2, as a three-dimensional (3D) Dirac semimetal, has zero-bandgap, high light absorption rate in broad spectral region, and higher mobility than graphene at room temperature. However, photoconductive detectors based Cd3As2 suffer low quantum efficiency due to the absence of high built-in field. Here, Cd3As2 nanoplate/multilayer MoS2 heterojunction photodetector was fabricated and achieved a quite high responsivity of 2.7×103 A/W at room temperature. The photodetector exhibits a short response time of in broad spectra region from ultraviolet (365 nm) to short-wavelength-infrared (1550 nm) and reached 65 μs at 650 nm. This work provides a great potential solution for high-performance photodetector and broadband imaging by combining 3D Dirac semi-metal materials with semiconductor materials.
关键词： 3D Dirac semimetals,broadband,photodetectors,responsivity,heterojunction
更新于2025-09-11 14:15:04
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A planar eight‐way compact substrate integrated waveguide based radial power divider with broadband performance
摘要： A compact broadband eight-way substrate integrated waveguide (SIW) based radial power divider at C-band is presented in the article. Bandwidth enhancement is achieved by employing planar impedance transformer consisting of an annular slot and circular patch at the input and output feed positions. The equivalent circuit analysis helps in the optimization of the annular slot and circular patch on the substrate. The proposed compact power divider has fractional bandwidth of 53.5% for 15 dB input return loss. Broadband characteristics are achieved without using any bulky mechanical arrangement for feed matching. It has a size of 0.72 λg 2 and the measured amplitude imbalance is within 0.5 dB at the center frequency of 6.6 GHz.
关键词： substrate integrated waveguide,compact design,power divider,broadband,eight-way
更新于2025-09-11 14:15:04
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Ultra-Broadband, High Speed, and High-Quantum-Efficiency Photodetectors Based on Black Phosphorus
摘要： Black phosphorus (BP), a narrow band gap semiconductor without out-of-plane dangling bonds, has shown promise for broadband and integrable photodetector applications. Simultaneously exhibiting high speed and high-efficiency operation, however, remains a critical challenge for current BP-based photodetectors. Here, we demonstrate a photodetector based on the BP-based van der Waals heterostructures. The developed photodetector enables broadband responses in the visible to mid-infrared range with external quantum efficiency (EQE) ranging from 20% to 52% at room temperature. These results together with noise measurements indicate the photodetector can detect light in the pico-watt range. Furthermore, the demonstrated BP detector has ultrafast rise (1.8 ns) and fall (1.68 ns) times, and its photoresponse exhibits reproducible switching behavior even under consecutive and rapid light intensity modulations (2100 cycles, 200 MHz), as indicated by the eye-diagram measurement. By leveraging these features, we show our BP heterostructures can be configured as a point-like detector in a scanning confocal microscopy, useful for mid-infrared imaging applications.
关键词： van der Waals heterostructures,mid-infrared imaging,Black phosphorus,high speed,broadband photoresponses,photodetector
更新于2025-09-11 14:15:04
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Damage analysis of a perfect broadband absorber by a femtosecond laser
摘要： Plasmonic metamaterial absorbers are particularly important in different applications such as photodetectors, microbolometers and solar cells. in this paper, we propose a tungsten boride (WB, a refractory ceramic) based broadband metamaterial absorber whose optical properties is numerically analyzed and experimentally characterized. We have also analyzed the damage characteristics of this absorber using a femtosecond laser and compared with an ordinary Au metamaterial absorber. We observe that WB has almost the double absorption bandwidth with absorption more than 90% over the spectral range of 950 to 1400 nm when compared with the Au counterpart. Furthermore, we show that Au metamaterial is damaged at the power of around 36.4 mW whereas WB metamaterial is not damaged at that power (WB has high tammann temperature than Au)-however the atom of WB material was knocked off by the bombardment of a femtosecond laser.
关键词： tungsten boride,femtosecond laser,broadband absorption,damage analysis,Plasmonic metamaterial absorbers
更新于2025-09-11 14:15:04
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BROADBAND PLASMONIC CIRCUITRY ENABLED BY CHANNEL DOMINO SPOOF PLASMONS
摘要： Building of compact plasmonic integrated circuits based on domino spoof plasmons (DSPs) is an important requirement and still a challenge. In this work, we report the ?rst demonstration of two kinds of channel domino plasmonic circuitries, which consist of an easy-to-manufacture periodic chain of metallic box-shaped elements inside two ?nite metallic plates. We reveal that only the channel DSPs itself rather than the hybrid TE10 and DSPs modes is supported in the part of the channel domino plasmonic waveguide with or without the metallic vias on both sides. Two channel domino plasmonic ?lters based on the e?cient transition structures are designed, and the simulated S-parameters and near electric ?eld distributions show excellent transmission performance in broadband. Utilizing the lateral insensitive property of these two channel DSPs, two kinds of broadband plasmonic power dividers/combiners are ?rstly implemented. Excellent transmission performance validates our optimizations and indicates that the proposed scheme can be easily extended to other bands. This work provides a new route for construction of deep-subwavelength DSP devices in application of high integration of microwave and terahertz circuits.
关键词： plasmonic integrated circuits,power dividers/combiners,broadband plasmonic filters,domino spoof plasmons,channel DSPs
更新于2025-09-11 14:15:04
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A Novel Temperature Controlled Broadband Metamaterial Absorber for THz Applications
摘要： A broadband switchable metamaterial absorber is investigated in this paper. The switchable response is achieved by utilizing the phase transition property of vanadium dioxide (VO2) that is thermally controlled. A novel band extension scheme is presented by introducing capacitive coupling effects among the resonators. By exploiting the coupling effect, near octave bandwidth is achieved when referred to an absorptivity of 90%. Further, by integrating the temperature controlled VO2 film into the dielectric layer, the proposed absorber can be switched between a frequency band from 0.32 THz to 0.56 THz and another band from 0.356 THz to 0.682 THz that is achieved by changing the operation temperature. Due to the symmetrical structure, the studied absorber features polarization insensitive and a wide incident angle of up to 50?. The broadband and switchable properties are discussed based on the resonant structure, surface current distributions, electric field distributions and impedance matching. It is noted the presented method can be scaled to other adjacent THz frequency band.
关键词： phase change material,metamaterial absorber,Broadband,switchable bandwidth
更新于2025-09-11 14:15:04
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Piezoelectric Modulation of Broadband Photoresponse of Flexible Tellurium Nanomesh Photodetectors
摘要： Flexible photodetector shows great potential applications in intelligent wearable devices, health monitoring, and biological sensing. In this work, single crystal β-tellurium nanowires were grown on flexible muscovite by molecular beam epitaxy, constructing high-density ordered nanomesh structure. The prepared photodetectors based on tellurium nanomesh exhibit excellent mechanical flexibility, fast response in a broad range from ultraviolet to near-infrared, and good photosensitivity. We found that the flexible photodetectors with Shottky contact drastically suppressed dark current, while the response speed was lowered in comparison to the devices with ohmic contact, as holes would take long time to tunnel through the Shottky barrier between metal and p-type Te. Moreover, photoresponse of flexible Shottky photodetectors can be modulated by piezoelectricity of tellurium, and pronounced photocurrent increase after many times of bend. Under external stress, polarization charges could tune Shottky barrier height of the metal/tellurium, resulting in variation of photocurrent. The research not only explores the broadband photoresponse and piezoelectric effect of tellurium nanomesh, but also promotes the integration and development of broadband flexible optoelectronic devices.
关键词： tellurium nanomesh,piezoelectric effect,broadband photoresponse,molecular beam epitaxy,flexible photodetector
更新于2025-09-11 14:15:04
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Ultrafast Broadband Diagnostics of the Filling of the s Band at the Two-Photon Femtosecond Laser Excitation of a Gold Film
摘要： The transmission of near infrared femtosecond laser pulses (wavelength of 800 nm) and supercontinuum radiation (300–750 nm) generated by them through a 50-nm gold film immersed in water has been experimentally studied at the power of focused laser radiation in the range of 1–10 GW. An increase in the excitation intensity is accompanied by the blueshift of the edge of the extinction band of the film, which is attributed to the filling of electronic states of the s band with a low density of states caused by two-photon interband transitions from d bands with a high density of states.
关键词： supercontinuum radiation,gold film,ultrafast broadband diagnostics,s band filling,two-photon femtosecond laser excitation
更新于2025-09-11 14:15:04
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A split-face randomized controlled trial of treatment with broadband light for enlarged facial pores
摘要： Background: Broadband light (BBL) is one of the intense pulsed light. BBL treatment for nonablative, noninvasive skin tightening and rejuvenation reportedly elicits satisfactory clinical outcomes. Up until now, self-controlled case series with objective evaluation of efficacy of facial pores in response to BBL treatment have not been reported. We aimed to assess its safety and efficacy on enlarged facial pores by objective measuring technique. Objective: To evaluate the efficacy and safety of BBL on the appearance of facial pores. Methods: 25 patients received five treatments with BBL at 2-week intervals. One split-face was treated by BBL, another split-face was untreated as a control. Objective measurements of the quantitative number of pores were calculated with a VISIA-CR imaging system. Skin elasticity, transepidermal water loss, skin sebum excretion, and skin surface hydration values were also evaluated by using an Elastimeter, Vapometer, Sebumscale, and Moisturemeter. Results: Pretreatment, the total average number of facial pores was 835.88 and 835.68 for BBL-treated facial sides and untreated facial sides, respectively (p ? .993). These values were 801.44 and 811.8, respectively, 2 months after the final treatment (p ? .606). There were no long-term side effects. Conclusion: BBL seems to be a safe and mildly effective approach to reduce detectable pores.
关键词： enlarge pore,Broadband light (BBL),intense pulsed light (IPL),laser,facial rejuvenation,photoaging,treatment,facial pore
更新于2025-09-11 14:15:04
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Broadband Linear-to-Circular Polarization Conversion Enabled by Birefringent Off-Resonance Reflective Metasurfaces
摘要： Due to the scarcity of circular polarization light sources, linear-to-circular polarization conversion is required to generate circularly polarized light for a variety of applications. Despite significant past efforts, broadband linear-to-circular polarization conversion remains elusive particularly in the terahertz and midinfrared frequency ranges. Here we propose a novel mechanism based on coupled mode theory, and experimentally demonstrate at terahertz frequencies that highly efficient (power conversion efficiency approaching unity) and ultrabroadband (fractional bandwidth up to 80%) linear-to-circular polarization conversion can be accomplished by the judicious design of birefringent metasurfaces. The underlying mechanism operates in the frequency range between well separated resonances, and relies upon the phase response of these resonances away from the resonant frequencies, as well as the balance of the resonant and nonresonant channels. This mechanism is applicable for any operating frequencies from microwave to visible. The present Letter potentially opens a wide range of opportunities in wireless communications, spectroscopy, and emergent quantum materials research where circularly polarized light is desired.
关键词： linear-to-circular polarization conversion,midinfrared,birefringent metasurfaces,terahertz,broadband
更新于2025-09-11 14:15:04