- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Large-Angle, Broadband and Multifunctional Directive Waveguide Scatterer Gratings
摘要： Conventional surface-relief gratings are inefficient at deflecting normally-incident light by large angles. This limits the overall efficiency of grating-based optical instruments and also restricts their use in many applications. Here, we demonstrate a simple approach for the design of diffraction gratings that can be highly efficient for large deflection angles, while also offering additional functionality. Such gratings are composed of a unit cell comprising a vertically-oriented asymmetric slot waveguide. The unit cell shows oscillating unidirectional scattering behavior that can be precisely tuned as a function of the waveguide length. This occurs due to interference between multiple modes excited in the structure by the incident light. In contrast to metasurface-based gratings with multiple resonant sub-elements, a periodic arrangement of such non-resonant diffracting elements allows for broadband operation and a strong tolerance for variations in angle of incidence. Full-wave simulations show that our grating designs can exhibit diffraction efficiencies ranging from 94% for a deflection angle of 47? to 80% for deflection angle of 80?. To demonstrate the multifunctionality of our approach, we also demonstrate a flat polarization beamsplitter and a polarization insensitive grating.
关键词： directional scattering,slot waveguides,diffraction gratings,metagratings,bianisotropy
更新于2025-09-12 10:27:22
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Slot-die processing and encapsulation of non-fullerene based ITO-free organic solar cells and modules
摘要： Organic photovoltaic (OPV) devices have shown remarkable performance progress in recent years, reaching current record power conversion efficiency (PCE) values of 16.4% for single junction and 17.3% for multi junction devices, owing mostly to the impressive developments made within synthesis of new non-fullerene acceptors. This progress places organic solar cells at the forefront of thin-film photovoltaic technology. However, in order to meet industrial demands and reach high performance values in industrial settings, further research and development efforts within Roll-to-Roll (R2R) and Sheet-to-Sheet (S2S) processing of OPV devices under ambient conditions are required. Furthermore, OPV modules being manufactured through such up-scaled processing techniques should ideally be developed from low cost materials, and show good stability towards various different operational stress conditions. In this work, we demonstrate combined R2R and S2S development of ITO-free OPV devices, which are based on the non-fullerene material system PBDB-T:ITIC. The devices are processed from R2R vacuum sputtering and S2S slot-die coating at ambient conditions, and reach cell PCE values of 5.5%. In addition, we introduce a correlation between different barrier films, both commercial and sputtered inorganic coatings on ultra-clean PET, and the lifetime of the developed devices. The results therefore demonstrate an important step in the development of OPV devices from R2R and S2S processes in industrial settings.
关键词： organic solar cells and modules,Roll-to-Roll (R2R),Sheet-to-Sheet (S2S),organic photovoltaics (OPV),slot-die coating,device encapsulation,non-fullerene acceptors
更新于2025-09-12 10:27:22
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Perylene Diimide based Organic Photovoltaics with Slot-Die Coated Active Layers from Halogen-Free Solvents in Air at Room Temperature
摘要： Herein, we investigate the role of processing solvent additives on the formation of polymer-perylene diimide bulk-heterojunction active layers for organic photovoltaics using both spin-coating and slot-die coating methods. We compare the effect of 1,8-diiodooctane (DIO) and diphenyl ether (DPE) as solvent additives on the aggregation behavior of the non-fullerene acceptor tPDI2N-EH in neat films and blended films with the benzodithiophene-quinoxaline (BDT-QX, QX-3) donor polymer, processed from toluene in air. DIO-processing crystallizes the tPDI2N-EH acceptor and leads to decreased solar cell performance. DPE-processing has a more subtle effect on the bulk-heterojunction morphology and leads to improved solar cell performance. Comparing spin vs. slot-die coating methods, the effect of DPE is prominent for slot-die coated active layers. While similar device power conversion efficiencies are achieved with active layers coated with both methods (ca. 7.3% vs. 6.5%), the use of DPE improves film quality when the slot-die coating method is employed.
关键词： Organic photovoltaics,Halogen-free processing,Perylene diimide,Slot-die coating,Solvent additive,Diphenyl ether,Quinoxaline,Morphology control
更新于2025-09-12 10:27:22
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Acetonitrile based single step slot-die compatible perovskite ink for flexible photovoltaics
摘要： The demonstration of photovoltaic devices with high power conversion efficiencies using low cost perovskite materials hints at the possibility of dramatically lowering the cost of solar energy. Key to further exploiting the potential of these materials is developing rapid processing techniques that can be used to deliver lower cost high throughput manufacture. This work details the development of low-viscosity rapid drying perovskite formulations designed to give high quality solar films when slot-die coated on flexible roll-to-roll compatible substrates. A single step slot-die compatible perovskite ink based on an acetonitrile/methylamine solvent system utilizing a chloride additive is developed, resulting in large area perovskite films from slot-die coating under ambient conditions. The drying conditions for the perovskite film are optimized and fast (<10 min), low temperature (<120 °C) drying of slot-die coated films on flexible substrates are demonstrated and result in high performance devices.
关键词： acetonitrile,chloride additive,flexible substrates,methylamine,photovoltaics,perovskite,slot-die coating
更新于2025-09-12 10:27:22
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Design of Ku-band Size-reduced Waveguide Slot Filter Antenna Loaded with Metal Ridges
摘要： A filter antenna based on waveguide structure is proposed in this paper, which reduces the size of the resonator by loading a metal ridge in the rectangular waveguide resonator to produce a capacitive effect. The filter antenna integrates the waveguide filter and the waveguide slot antenna radiation array, and achieves a better matching of filtering characteristics and impedance. The simulation results show that the centre frequency of waveguide filter antenna is 15GHz and the relative bandwidth 2%; the return loss is more than 16.78dB; the peak gain of waveguide filter antenna reaches 12dBi.To summarize, the performance is excellent under the case of simple structure. The proposed filter antenna lays the foundation for the realization of integrated communication system and can be used in satellite and radar communication system.
关键词： waveguide slot filter antenna,metal ridges,size-reduced,Ku-band
更新于2025-09-12 10:27:22
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Meta-waveguide analysis and implementation for using as a slot array antenna
摘要： This paper presents a novel concept named meta-waveguide structures to design slot array antennas based on metasurface. The proposed method investigates the geometrical parameters of the embedded metasurface and their relations to build up the engineered electric and magnetic fields to introduce efficient slot array antennas. This approach eliminates the necessity of using the well-known offsets in typical slot arrays, which can be benefited from linear array theorem. This idea is realized by employing successive filed curvature along the propagation direction, utilizing periodic metasurfaces. Thereafter, a step-by-step algorithm is recommended to design an efficient slot array antenna. Finally, a prototype is fabricated and tested experimentally validating the theoretical calculations.
关键词： Metasurface,slot array antenna,slot waveguide array,meta-waveguide
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Conference on Computational Electromagnetics (ICCEM) - Shanghai, China (2019.3.20-2019.3.22)] 2019 IEEE International Conference on Computational Electromagnetics (ICCEM) - A compact coplanar waveguide feed bow-tie slot antenna for WIMAX, C and X band applications
摘要： In this paper, a planar bow-tie slot antenna with coplanar waveguide fed for tri-band i.e. WIMAX, C and X band wireless communication applications is proposed. This antenna has been designed to meet the prerequisite of multiple resonant frequencies by setting up the proper dimensions of the bow-tie arm slots and feed line cutout slots. The dimensions corresponds to the tri-band resonant frequencies, are obtained by engraving slots of distinct length and width above the ground plane. The antenna is fed by 50? coplanar waveguide feed line. Physical size of the proposed antenna is 30×60 mm2 designed on thick substrate. The copper cladding ArlonCuClad217(tm) woven fiberglass laminate material with dielectric loss tangent 0.0009 and relative permittivity 2.17 is used. The gain, impedance bandwidths, return loss, and VSWR of proposed antenna has been analyzed and discussed. Moreover, the extensive parametric study has been carried out with dimensions of feed line cutout. The simulation results have shown that the designed prototype of an antenna exhibits the peak realized gain of 6.9dBi and average gain of 2.3dBi.The proposed antenna has three operating bands, which are suitable for WIMAX, C-band and X-band applications.
关键词： Tri-band,CPW-fed,Slot antennas,Gain,Bow-tie arm
更新于2025-09-11 14:15:04
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Mode Sensitivity Analysis of Subwavelength Grating Slot Waveguides
摘要： In this paper, we investigate the mode sensitivity (Smode) of subwavelength grating slot (SWGS) waveguides. Smode is an important parameter in various waveguide-based photonic circuits such as sensors, modulators, and thermally-controlled devices. It is a measure of the sensitivity of the waveguide effective index towards the refractive index perturbations in the cladding medium. The SWGS waveguide exhibits high mode sensitivity, as it combines sensitivity enhancement features of both slot and subwavelength grating waveguides. Finite-difference time-domain simulations are performed for the analysis, design, and optimization of the hybrid structure. The SWGS waveguide is incorporated into a Mach-Zehnder interferometer and fabricated on a silicon-on-insulator platform for the experimental estimation of Smode. The measured Smode value of 79% is consistent with the theoretical prediction of 83%.
关键词： Subwavelength grating,sensor,silicon-on-insulator,integrated optics,slot waveguide
更新于2025-09-11 14:15:04
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Bandwidth improvement of substrate integrated waveguide cavity-backed slot antenna with dielectric resonators
摘要： In the paper, a low profile substrate integrated waveguide based circular-shaped cavity-backed antenna is delineated to work at WLAN U-NII mid band and a slender rectangular slot is then placed at its center on the ground plane for radiation. The parent antenna radiates at 5.33 GHz with a gain of 4.9 dBi; depicting a narrow impedance bandwidth of 50 MHz. The antenna is modified by placing dielectric resonators of different shapes over the slot to enhance the bandwidth. The new antennas thus produced have an impedance bandwidth of 750 MHz with cylindrical-shaped and rectangular-shaped dielectric resonators which reflect bandwidth enhancement of 700 MHz for both the cases and an impedance bandwidth of 710 MHz with hemispherical-shaped dielectric resonator reflecting bandwidth enhancement of 660 MHz. The gain of the modified antennas is of the order of 4.7 dBi which basically indicates not much degradation in gain as compared to the parent antenna. All the antennas are delineated using Arlon AD270 substrate material with the results obtained after simulation juxtaposed with the ones obtained through measurement.
关键词： Bandwidth enhancement,WLAN U-NII mid band,Cavity-backed slot antenna,Substrate integrated waveguide,Dielectric resonator
更新于2025-09-11 14:15:04
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A broadband terahertz metamaterial absorber enabled by the simple design of a rectangular-shaped resonator with an elongated slot
摘要： Broadband metamaterial absorbers are of critical importance in practical applications, but their obtainment approaches are quite complex at present. We demonstrate here that a fairly simple structure design formed by a rectangular-shaped resonator having an elongated slot can be utilized to achieve a broadband absorption response at terahertz frequencies. More than 50% absorption in a continuous frequency range of 1.62 THz (with a central frequency of 2.05 THz) can be gained, and its relative absorption bandwidth is 79.02%, which is superior to that of previous broadband absorption devices. The basic principle of the broadband absorption originates from the superposition of four di?erent but narrowly separated resonance peaks that resulted from di?erent response positions of the suggested resonator. Results further reveal that the broadband terahertz absorption performance (or its four resonance peaks) can be controlled by the resonator dimensions. The suggested method can provide a new type of design strategy to realize broadband integrated terahertz absorption devices.
关键词： resonance peaks,rectangular-shaped resonator,elongated slot,broadband metamaterial absorbers,terahertz frequencies
更新于2025-09-11 14:15:04