- 标题
- 摘要
- 关键词
- 实验方案
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Low-loss and broadband non-volatile phase-change directional coupler switches
摘要： An optical equivalent of the field-programmable gate array (FPGA) is of great interest to large-scale photonic integrated circuits. Previous programmable photonic devices relying on the weak, volatile thermo-optic or electro-optic effect usually suffer from a large footprint and high energy consumption. Phase change materials (PCMs) offer a promising solution due to the large non-volatile change in the refractive index upon phase transition. However, the large optical loss in PCMs poses a serious problem. Here, by exploiting an asymmetric directional coupler design, we demonstrate non-volatile PCM-clad silicon photonic 1 × 2 and 2 × 2 switches with a low insertion loss of ~1 dB and a compact coupling length of ~30 μm while maintaining a small crosstalk less than ?10 dB over a bandwidth of 30 nm. The reported optical switches will function as the building blocks of the meshes in the optical FPGAs for applications such as optical interconnects, neuromorphic computing, quantum computing, and microwave photonics.
关键词： Silicon photonics,Non-volatile,Optical switches,Phase-change materials,Reconfigurable photonics,Integrated photonic devices
更新于2025-09-23 15:23:52
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Versatile and Switchable Responsive Properties of a Lanthanide-Viologen Metal-Organic Framework
摘要： Metal–organic frameworks (MOFs) provide intriguing platforms for the design of responsive materials. It is challenging to mobilize as many components as possible of a MOF to collaboratively accomplish multiple responsive properties. Here, reversible photochromism, piezochromism, hydrochromism, ionochromism, and luminescence modulation of an ionic Eu(III) MOF is reported furnished by cationic electron-deficient viologen units and exchangeable guest anions. Mechanistically, the extraordinarily versatile responsive properties are owed to electron transfer (ET), charge transfer (CT), and energy transfer, involving viologen as electron acceptor, anion as electron donor, luminescing Eu(III) as energy donor, and anion-viologen CT complex or ET-generated radical as energy acceptor (luminescence quencher). Moreover, guest anions and waters provide flexible handles to control the ET-based responsive properties. Water release/reuptake or exchange with organic solvents can switch on/off the response to light, while reversible anion exchange can disenable or awaken the responses to pressure, light, and water release/reuptake. The impacts of water and anions on ET are justified by the high polarity and hydrogen-bonding capability of water, the different electron donor strength of anions, and the strong I?-viologen CT interactions. The rich responsive behaviors have great implications for applications such as pressure sensors, iodide detection, and chemical logic gates.
关键词： metal–organic frameworks,electron transfer,charge transfer,luminescence switches,piezochromism
更新于2025-09-23 15:23:52
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A Visible-Light-Driven Molecular Motor Based on Pyrene
摘要： The aromatic core of an overcrowded alkene-based molecular motor is extended with the goal of inducing isomerization with visible light instead of harmful UV light. In our design, the common naphthalene moiety in the upper half of the motor is changed to pyrene. The photochemical and thermal isomerization processes are studied in detail using DFT calculations as well as NMR and UV/vis spectroscopy. Our studies confirm that extension of the π-system of the upper half successfully leads to a shift of the excitation wavelength into the visible region, while retaining proper rotary function.
关键词： Molecular Switches,Photochromism,Overcrowded Alkenes,Molecular Motors,Pyrene
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Va?ster?s (2018.9.3-2018.9.6)] 2018 IEEE Conference on Antenna Measurements & Applications (CAMA) - Overview On Functional Materials for Frequency Tunable Antennas
摘要： We report the integration of different kind of materials with improved and adapted properties within antenna designs. In this framework, an overview of three frequency tunable antennas will be presented. Two of them are based on radiating slot elements integrating a Ba2/3Sr1/3TiO3 (BST)-based tunable capacitance and therefore present a continuous tunability for the first one while the second one is integrating a VO2-based switch for a discrete tuning. The third design presented in this paper propose a frequency reconfigurable composite GeTe-metal patch antenna operating at the millimeter-waves (24-30 GHz) whose resonant frequency can be tuned and repeatedly changed upon the application of successive laser pulses.
关键词： Frequency tunable antenna,VO2 switches,BST tunable capacitance,Phase Change Materials
更新于2025-09-23 15:23:52
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A UV-Responsive Multifunctional Photoelectric Device Based on Discotic Columnar Nanostructures and Molecular Motors
摘要： Orientation control of ordered materials would not only produce new physical phenomenon but also facilitate the development of fancy devices. Discotic liquid crystals (DLCs) form 1D charge transport pathway by self-organizing into columnar nanostructures via π–π stacking. However, controlling the electrical properties in such nanostructures with some direct and instant way is a formidable task for their high viscosity and insensitivity to external stimuli. Herein, the arbitrary control over electrical conductivity of such columnar nanostructures is achieved with UV light by incorporating DLCs with molecular motors. Highly ordered DLC microstripe arrays are generated on desired substrate through a capillary bridge dewetting strategy. The conductivity of the microstripes could be continuously modulated by 365 nm light due to the influence of molecular motion under UV irradiation on the electron orbital overlap of columnar nanostructures. This is so because the disorder degree of the DLC molecules is associated with the intensity of UV light and the doping concentration of molecular motors. Moreover, the device shows memory effect and reversible conductivity change. The DLC microstripe arrays are very promising for the applications in UV detectors, memory devices, optical switches, and so on.
关键词： discotic liquid crystals,tunable conductivity,molecular motors,overcrowded alkenes,optical switches
更新于2025-09-23 15:22:29
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Flexible Filtering Element on SOI with Wide Bandwidth tunability and Full FSR tuning
摘要： We demonstrate a Silicon-on-Insulator flexible filtering element, relying on two serially coupled micro ring resonators equipped with three thermo-optically tuned Mach-Zehnder interferometers, acting as variable optical couplers. A single electrode configuration is adopted, enabling the low-complexity thermo-optical control of the filtering element for bandwidth and wavelength tuneability. The module's performance has been studied in detail via simulation analysis and the obtained results were verified through experimental evaluation. Wide bandwidth tunability from 9 GHz to 103 GHz is achieved with a power efficiency of 0.284 mW/GHz, while full Free Spectral Range wavelength tuning is achieved with an efficiency of 0.297 mW/GHz. Module's insertion loss lays below 3 dB.
关键词： Silicon photonics,Optical switches,Microring resonators,Bandwidth flexibility,Thermo-optic control,Wavelength division multiplexing,Optical filters
更新于2025-09-23 15:22:29
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Oxidative and reductive cyclization in stiff dithienylethenes
摘要： The electrochemical behavior of stiff dithienylethenes, undergoing double bond isomerization in addition to ring-closure, has been investigated. Electrochromism was observed in almost all cases, with the major pathway being the oxidatively induced cyclization of the open isomers. The influence of the ring size (to lock the reactive antiparallel conformation) as well as substituents (to modulate the redox potential) on the electrocyclization was examined. In the series of derivatives with 6-membered rings, both the E- and the Z-isomer convert to the closed isomer, whereas for the 7-membered rings no cyclization from the E-isomer was observed. For both stiff and normal dithienylethenes bearing benzonitrile substituents an additional and rare reductive electrocyclization was observed. The mechanism underlying both observed electrocyclization pathways has been elucidated.
关键词： (spectro)electrochemistry,electrochromism,molecular switches,diarylethenes
更新于2025-09-23 15:22:29
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Picosecond-Range Avalanche Switching of Bulk Semiconductors Triggered by Steep High-Voltage Pulses
摘要： Experimental observation and numerical simulations of sub-nanosecond avalanche switching of Si and ZnSe bulk semiconductor structures initiated by high-voltage pulses with steep (dU/dt > 10 kV/ns) ramp are reported. The measured switching time is ～100 ps. The switching is sustainable and repetitive and has negligible jitter. Comparison of the experimental and numerical results suggests that after switching, the whole volume of the structure is uniformly ?lled with nonequilibrium electron–hole plasma.
关键词： semiconductor lasers,Power electronics,pulse-power system switches
更新于2025-09-23 15:21:21
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[IEEE 2019 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC) - Ixtapa, Mexico (2019.11.13-2019.11.15)] 2019 IEEE International Autumn Meeting on Power, Electronics and Computing (ROPEC) - Correlation Study between Photovoltaic Power Output and Environmental Variables Using an Embedded IoT System
摘要： An ultrafast electro-optical amplified switch based on chip-on-carrier semiconductor optical amplifier with high optical contrast (33 dB) is presented. Switching times up to 115 ps with small overshoot were achieved by using the multi-impulse step injected current technique. These results are compared with previous preimpulse step injected current technique, and achieve a reduction of the inherent, post switching gain fluctuations without worsening the switching times. In addition, pulse formats for controlling such a kind of electro-optical switches are numerically analyzed and compared with experiments.
关键词： Electro-optics switches,semiconductor optical amplifiers,optical switches
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Studies on Co-sputtered Al-Zn-Sn-O Films: A New TCO for Thin film Solar Cells
摘要： Hybrid analog/digital multiple-input multiple-output architectures were recently proposed as an alternative for fully digital-precoding in millimeter wave wireless communication systems. This is motivated by the possible reduction in the number of RF chains and analog-to-digital converters. In these architectures, the analog processing network is usually based on variable phase shifters. In this paper, we propose hybrid architectures based on switching networks to reduce the complexity and the power consumption of the structures based on phase shifters. We define a power consumption model and use it to evaluate the energy efficiency of both structures. To estimate the complete MIMO channel, we propose an open-loop compressive channel estimation technique that is independent of the hardware used in the analog processing stage. We analyze the performance of the new estimation algorithm for hybrid architectures based on phase shifters and switches. Using the estimate, we develop two algorithms for the design of the hybrid combiner based on switches and analyze the achieved spectral efficiency. Finally, we study the tradeoffs between power consumption, hardware complexity, and spectral efficiency for hybrid architectures based on phase shifting networks and switching networks. Numerical results show that architectures based on switches obtain equal or better channel estimation performance to that obtained using phase shifters, while reducing hardware complexity and power consumption. For equal power consumption, all the hybrid architectures provide similar spectral efficiencies.
关键词： channel estimation,precoding,Millimeter wave,hybrid architecture,switches
更新于2025-09-23 15:21:01