- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Complete Scene Reconstruction by Merging Images and Laser Scans
摘要： Optical fibre transmission has enabled greatly increased transmission rates with 10 Gb/s common in local area networks. End users find wireless access highly convenient for mobile communication. However, limited spectrum availability at microwave frequencies results in per-user transmission rates limited to much lower values, e.g., 500 Mb/s for 5-GHz band IEEE 802.11ac. Extending the high data-rate capacity of optical fiber transmission to wireless devices requires greatly increased carrier frequencies. This paper will describe how photonic techniques can enable ultrahigh capacity wireless data distribution and transmission using signals at millimeter-wave and TeraHertz (THz) frequencies.
关键词： photonic integrated circuits,microwave photonics,Broadband communication,optical mixing,optical heterodyne,millimeter (mm)-wave generation,optical phase lock loops,semiconductor lasers
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE Conference on Power Electronics and Renewable Energy (CPERE) - Aswan City, Egypt (2019.10.23-2019.10.25)] 2019 IEEE Conference on Power Electronics and Renewable Energy (CPERE) - Analysis, Design and Simulation of a DC Photovoltaic Microgrid with Electric Vehicle Charging Capability
摘要： Optical fibre transmission has enabled greatly increased transmission rates with 10 Gb/s common in local area networks. End users find wireless access highly convenient for mobile communication. However, limited spectrum availability at microwave frequencies results in per-user transmission rates limited to much lower values, e.g., 500 Mb/s for 5-GHz band IEEE 802.11ac. Extending the high data-rate capacity of optical fiber transmission to wireless devices requires greatly increased carrier frequencies. This paper will describe how photonic techniques can enable ultrahigh capacity wireless data distribution and transmission using signals at millimeter-wave and TeraHertz (THz) frequencies.
关键词： optical heterodyne,optical mixing,optical phase lock loops,millimeter (mm)-wave generation,microwave photonics,photonic integrated circuits,Broadband communication,semiconductor lasers
更新于2025-09-19 17:13:59
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Generation of Nearly Flattop Ultra-Broadband Response in a QPM Device Using a Phase Shifter
摘要： We have theoretically demonstrated the efficient generation of nearly flattop ultra-broadband response in a periodic quasi-phase matching (QPM) device using a single phase shifter (PS) domain. The flat broadband response is generated using optical parametric generation (OPG) with a QPM device of grating period Λ = 27 μm. The choice of grating period and pump source depends on the group velocities of signal and idler wavelengths to match close to the degeneracy point. We have identified the location of phase shifter domain, which generates a nearly flattop OPG gain bandwidth of ?λ = 1.41 μm. The variations in broadband response are studied when the location and width of phase shifter domains are altered. When compared to a periodic device, the phase shifter domain included QPM structure exhibits higher tolerance to temperature in retaining the smoothness of the broadband response. Furthermore, we have generated the same ultra-broadband response by introducing multiple phase shifter domains at suitable locations in a periodic QPM device.
关键词： optical superlattices,optical mixing,Nonlinear optics,optical harmonic generation
更新于2025-09-10 09:29:36
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All-optical field-free three-dimensional orientation of asymmetric-top molecules
摘要： Orientation and alignment of molecules by ultrashort laser pulses is crucial for a variety of applications and has long been of interest in physics and chemistry, with the special emphasis on stereodynamics in chemical reactions and molecular orbitals imaging. As compared to the laser-induced molecular alignment, which has been extensively studied and demonstrated, achieving molecular orientation is a much more challenging task, especially in the case of asymmetric-top molecules. Here, we report the experimental demonstration of all-optical field-free three-dimensional orientation of asymmetric-top molecules by means of phase-locked cross-polarized two-color laser pulse. This approach is based on nonlinear optical mixing process caused by the off-diagonal elements of the molecular hyperpolarizability tensor. It is demonstrated on SO2 molecules and is applicable to a variety of complex nonlinear molecules.
关键词： ultrashort laser pulses,nonlinear optical mixing,hyperpolarizability tensor,molecular orientation,asymmetric-top molecules
更新于2025-09-09 09:28:46
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Comparison of Optical Single Sideband Techniques for THz-over-fiber Systems
摘要： The use of single sideband (SSB) signals and envelope detection is a promising approach to enable the use of economic free-running lasers in photonic THz communications. To combat the signal-signal beat interference (SSBI) associated with envelope detection, broad guard bands (GBs) may be used given the large unregulated spectrum available at THz frequencies (100 GHz – 10 THz). In this scenario, the conventional way of generating SSB signals through a digital SSB filter (here referred to as the CSSB scheme) would require quite high analog digital-to-analog converter (DAC) bandwidths. Digital virtual SSB (DVSSB) and analog virtual SSB (AVSSB) have been proposed in direct-detection optical systems for relaxing the DAC bandwidth requirements. In this paper, we compare the three techniques through simulations and implement them, for the first time, in a THz-over-fiber (ToF) system operating at 250 GHz. For the transmission experiments we employ 5 GBd 16-QAM signals with three different GBs (5.5 GHz, 4.75 GHz and 3.5 GHz). The simulations show that the best performance is obtained with the AVSSB technique, while the worst is obtained with the DVSSB scheme, where the quality of the generated sideband degrades with carrier-to-sideband power ratio. In the experimental transmissions, where receiver noise was the main source of noise, similar behavior was found between the three techniques. At the 3.5 GHz GB, however, the DVSSB exhibited a penalty of 1 dB with respect to the other two. This is likely to be due to nonlinear distortions caused by the increase in the virtual tone power.
关键词： microwave photonics,Broadband communication,semiconductor lasers,photonic integrated circuits,digital signal processing,envelope detectors,optical mixing,millimeter wave communication
更新于2025-09-04 15:30:14