Pulsed THz radiation under ultrafast optical discharge of vacuum photodiode
link.springer.com
link.springer.com
> Abstract: In this paper, we first present an experimental demonstration of terahertz radiation pulse generation with energy up to 5 pJ under the electron emission during ultrafast optical discharge of a vacuum photodiode. We use a femtosecond optical excitation of metallic copper photocathode for the generation of ultrashort electron bunch and up to 45 kV/cm external electric field for the photo-emitted electron acceleration. Measurements of terahertz pulses energy as a function of emitted charge density, incidence angle of optical radiation and applied electric field have been provided. Spectral and polarization characteristics of generated terahertz pulses have also been studied. The proposed semi-analytical model and simulations in COMSOL Multiphysics prove the experimental data and allow for the optimization of experimental conditions aimed at flexible control of radiation parameters.
- "When ultrashort electron bunch accelerates and drastically stops, it can generate terahertz radiation" (2024) https://phys.org/news/2024-07-ultrashort-electron-bunch-dras...
"Earth-abundant Cu-based metal oxide photocathodes for photoelectrochemical water splitting" (2020) https://pubs.rsc.org/en/content/articlelanding/2020/ee/d0ee0...
LightSlinger antennae are FTL within the dielectric, but the EMR is not FTL; from https://news.ycombinator.com/item?id=37342016 :
> "Smaller, more versatile antenna could be a communications game-changer" (2022) https://news.ycombinator.com/item?id=37337628 :
> LightSlingers use volume-distributed polarization currents, animated within a dielectric to faster-than-light [FTL] speeds, to emit electromagnetic waves. (By contrast, traditional antennas employ surface currents of subluminally moving massive particles on localized metallic elements such as dipoles.) Owing to the superluminal motion of the radiation source, LightSlingers are capable of “slinging” tightly focused wave packets with high precision toward a location of choice. This gives them potential advantages over phased arrays in secure communications such as 4G and 5G local networks
> "Coherent interaction of a-few-electron quantum dot with a terahertz optical resonator" (2023) https://arxiv.org/abs/2204.10522 ; "Researchers solve a foundational problem in transmitting quantum information" (2024) [w/ AlGaAs/GaAs]
Though the [qubit wave function transmission range] on that is only tens to a hundred micrometers. With 5pJ microwave like OT, what is the range?
From "Can you pump water without any electricity?" https://news.ycombinator.com/item?id=40619745 :
> - /? praveen mohan lingam: https://www.youtube.com/results?search_query=praveen+mohan+l...