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Stress control of tensile-strained In <sub/>1?</sub><sub/><i>x</i> </sub> Ga <sub/><i>x</i> </sub> P nanomechanical string resonators
摘要： We investigate the mechanical properties of freely suspended nanostrings fabricated from tensile-stressed, crystalline In1?xGaxP. The intrinsic strain arises during epitaxial growth as a consequence of the lattice mismatch between the thin film and the substrate, and is confirmed by x-ray diffraction measurements. The flexural eigenfrequencies of the nanomechanical string resonators reveal an orientation dependent stress with a maximum value of 650 MPa. The angular dependence is explained by a combination of anisotropic Young’s modulus and a change of elastic properties caused by defects. As a function of the crystal orientation, a stress variation of up to 50% is observed. This enables fine tuning of the tensile stress for any given Ga content x, which implies interesting prospects for the study of high Q nanomechanical systems.
关键词： In1?xGaxP,tensile-strained,defects,nanomechanical string resonators,Young’s modulus,stress control
更新于2025-09-09 09:28:46
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Pinning Transition of Bose-Einstein Condensates in Optical Ring Resonators
摘要： We experimentally investigate the dynamic instability of Bose-Einstein condensates in an optical ring resonator that is asymmetrically pumped in both directions. We find that, beyond a critical resonator-pump detuning, the system becomes stable regardless of the pump strength. Phase diagrams and quenching curves are presented and described by numerical simulations. We discuss a physical explanation based on a geometric interpretation of the underlying nonlinear equations of motion.
关键词： dynamic instability,pinning transition,optical ring resonators,Bose-Einstein condensates
更新于2025-09-09 09:28:46
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Automatic Monitor-Based Tuning of an RF Silicon Photonic 1X4 Asymmetric Binary Tree True-Time-Delay Beamforming Network
摘要： Photonic beamforming networks are promising candidates to achieve power-efficient transmission in future cellular communication systems. However, sensitivity to process and temperature variations necessitates an automatic calibration solution to enable robust operation. This paper demonstrates fully automatic monitor-based tuning of an integrated optical ring resonator-based 1X4 asymmetric binary tree optical beamforming network (OBFN). The proposed monitor-based tuning algorithm compensates fabrication variations and thermal crosstalk by controlling micro-heaters individually using information from electrical monitors. This algorithm is demonstrated on an OBFN that operates at 30 GHz with 2 GHz bandwidth and is fabricated in a standard silicon photonics foundry process. Successful calibration of the OBFN from a severely degraded initial response to the well-defined group delay responses required for a targeted radiating angle over 60? (?30? to 30?) in a linear beamforming antenna array is achieved. This fully automatic tuning approach opens the possibility of employing silicon OBFNs in real wideband mm-wave wireless communication systems.
关键词： optical ring resonators,thermal crosstalk,photonic integrated circuits,phased arrays,RF photonics,optical beamforming,true time delays,Microwave photonics
更新于2025-09-09 09:28:46
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UWB MONOPOLE ANTENNA WITH TRIPLE BAND-NOTCHED CHARACTERISTIC BASED ON A PAIR OF NOVEL RESONATORS
摘要： In this paper, a novel microstrip-fed compact antenna with triple band-notched characteristics is presented for ultrawideband (UWB) applications. The antenna consists of a circular radiating patch, a 50 ? microstrip feed line, a partially slotted ground plane, and a pair of modi?ed capacitance loaded loop (MCLL) resonators. The novel resonators are symmetrically located in the vicinity of the feed line to achieve triple band-notched characteristics, such as 3.4–3.7 GHz for WiMAX, 5.15–5.825 GHz for WLAN, 7.25–8.395 GHz for X-band satellite communication. The good performance of triple notched bands, stable gain and omnidirectional radiation patterns in the operating bands make the proposed antenna a good candidate for UWB utilization.
关键词： MCLL resonators,WiMAX,monopole antenna,UWB,WLAN,X-band satellite communication,triple band-notched
更新于2025-09-09 09:28:46
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Accurate Extraction of Equivalent Circuit Parameters of Spiral Resonators for the Design of Metamaterials
摘要： Spiral resonators (SRs) are one of the most common typologies of resonant magnetic unit cell for the realization of metamaterials. The precise knowledge of their lumped electric properties (RLC parameters) is of crucial importance in the metamaterial design. Thus, an accurate and unambiguous procedure for estimating the value of the RLC lumped parameters of compact SRs is introduced. The proposed procedure relies on a rigorous approach allowing a complete characterization of SRs also in terms of Q-factor. The method is general and valid for other shapes of resonators. The estimations have been finally verified by performing measurements on fabricated SRs through a magnetic probe.
关键词： spiral resonators (SRs),scattering parameters,unit cell,Metamaterial,resonant frequency
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Wireless Communications, Signal Processing and Networking (WiSPNET) - Chennai, India (2018.3.22-2018.3.24)] 2018 International Conference on Wireless Communications, Signal Processing and Networking (WiSPNET) - Dual-band Bandpass Filter Using Complementary Split Ring Resonators for X-Band Applications
摘要： This paper is focused on Complementary Split Ring Resonator (CSRR) to design a dual band bandpass filter (BPF) for X-Band frequencies using metamaterial concept. To achieve the functionalities of metamaterials, rectangular shaped complementary split ring resonators are etched in the ground plane along with λ/4 microstrip lines on the top. The inner and the outer rings are joined at the center through a gap. The length of the inner ring and the outer ring are calculated to make the BPF operating at 8.2 GHz and 9 GHz in X-Band. The width of the inter-connecting gap is changed to control the passband edges. An equivalent circuit model is proposed for the designed dual-band BPF to understand the working of the basic cell along with a microstrip line. By varying the length and width of the CSRR and changing the microstrip line dimensions two resonances are can be adjusted and finally fixed at our desired resonating frequencies. The results of EM simulation and the circuit simulation are compared to confirm the validity of the proposed design.
关键词： Bandpass filter,Complementary Split Ring Resonators,Dual-band filter,Metamaterials
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - Bangalore, India (2018.9.19-2018.9.22)] 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - Compact Tunable Dual-band Bandpass Filter using Edge-open Split Ring Resonators for X-Band Applications
摘要： In this paper, a dual-band bandpass ?lter(BPF) is designed using edge-open Split Ring Resonators(SRR) which is obtained by modifying the conventional SRRs. The inner ring and the outer ring of the edge-open SRRs are connected to stubs to get dual passbands with improved ?lter characteristics. The rings of the SRR are loaded with varactor diodes to tune the individual passbands of the proposed BPF. The ?rst passband can be tuned independently by varying the capacitance of the varactor diode D1 while the second passband remains unchanged by ?xing the capacitance of the varactor diode D2 and vice versa. Hence, the proposed ?lter helps in tuning both the passbands independently of about 0.6GHz for the ?rst passband & 0.3GHz for the second passband and achieves compactness in size of about 20mm x 14mm. The ring equivalents of each rings and the obtained S-parameter results of the proposed BPF while tuning the individual passbands are discussed in this paper.
关键词： Split Ring Resonators,Varactor Diodes,Tunable ?lter,Metamaterials,Dual band bandpass ?lter
更新于2025-09-09 09:28:46
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A NOVEL POLARIZATION INDEPENDENT CHIPLESS RFID TAG USING MULTIPLE RESONATORS
摘要： A novel polarization independent RFID tag employing multiple resonators is proposed. The prototype of the tag is fabricated on a low-cost substrate of dielectric constant 4.4 and loss tangent 0.02. Designing a reader for chipless RFID is a hard task since both the polarization and operating frequency agility have to be implemented. The new tag design proposed in this paper is polarization independent, making the design of the reader easier. A prototype of a 3 bit data encoded tag is demonstrated using single structure which can be extended to any order by cascading. This new design is experimentally validated in the frequency domain using monostatic measurement with magnitude response to decode the information.
关键词： polarization independent,multiple resonators,low-cost substrate,chipless RFID tag,frequency domain
更新于2025-09-09 09:28:46
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Tunable near-infrared perfect absorber based on the hybridization of phase-change material and nanocross-shaped resonators
摘要： Ge2Sb2Te5 (GST) is a kind of non-volatile chalcogenide phase-change material, which has a significant difference in permittivity between its amorphous and crystalline states in the infrared range. On account of this remarkable property, the combination of GST and metamaterials has great potential in tunable meta-devices. In this paper, a perfect absorber based on a nanocross-resonator array stacked above a GST spacer layer and an Au mirror (i.e., a metal-dielectric-metal configuration) is designed and experimentally demonstrated. A thin indium tin oxide (ITO) protective layer is inserted between the GST spacer and the Au resonator to avoid heat-induced oxidation of the GST layer during phase transition. We found that the ITO layer not only can protect the GST layer from deterioration, but also allows a significant blue shift in the absorption peak from 1.808 lm to 1.559 lm by optimizing the thickness of the two dielectric layers without scaling down the size of the metal structure, which provides a more feasible idea in pushing the absorption peak to higher frequency. The LC circuit model is presented to explain this blue-shift phenomenon, which is mainly attributed to the engineering of the dielectric environment of the parallel plate capacitance. In addition, such good performance in dynamitic modulation makes this perfect absorber a robust candidate for optical switching and modulating in various situations.
关键词： metamaterials,near-infrared,nanocross-shaped resonators,phase-change material,tunable,perfect absorber,GST
更新于2025-09-09 09:28:46
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BANDPASS FILTERS WITH IMPROVED SELECTIVITY BASED ON DUAL-MODE RING RESONATORS
摘要： Two novel microstrip bandpass ?lters with improved selectivity based on dual-mode ring resonators are proposed. Tow and four transmission zeros close to the passband are realized to improve the selectivity for the passband. Sixth-order passband is realized with two open/shorted stubs and a dual-mode ring resonator. The transmission zeros near the passband can be adjusted conveniently by changing the characteristic impedances of the coupled lines. For demonstration, two planar bandpass ?lters (3-dB bandwidths 20.9%, 20.2%) are designed and fabricated.
关键词： dual-mode ring resonators,transmission zeros,microstrip bandpass filters,selectivity
更新于2025-09-04 15:30:14