Researchers at the University of Sydney have combined a photonic filter and modulator on a single chip in a way that allows them to precisely detect signals across a wide band of radiofrequency (RF) spectrum. The work brings photonic chips one step closer to one day potentially replacing bulkier and more complex electronic RF chips in fiber optic networks.
The Sydney team exploited stimulated Brillouin scattering, a technique which involves converting electrical fields into pressure waves in certain insulators, such as optical fibers. In 2011, the researchers reported that Brillouin scattering held potential for high-resolution filtering, and developed new manufacturing techniques to combine a chalcogenide Brillouin waveguide on a silicon chip. In 2023, they managed to combine a photonic filter and modulator on the same type of chip. The combination gives the experimental chip a spectral resolution of 37 megahertz and a wider bandwidth than preceding chips, the team reported in a paper published 20 November in Nature Communications.
VLEO refers to orbits between about 100 kilometers and 300 or 400 km (although the exact range depends on who you ask), in contrast to LEO, which starts around 300 or 400 km and extends up to 2,000 km. The first satellites in VLEO were short-lived US spy satellites in the 1960s and 1970s, which dropped their film payloads for mid-air capture by aircraft. It’s probable that their descendants are still dipping into VLEO.
The Cyberspace Administration of China (CAC) would like your opinion on how it should regulate facial recognition. The agency issued draft rules on 8 August with a one-month comment period. The rules follow several years of court battles over private companies’ widespread use of the technology: Public toilets and zoos have sparked debate and lawsuits over their use of facial-recognition technology.
However, the main driver of the tech so far may be public security forces, according to recent studies. And even under the new rules, security forces will not need permission to identify individuals with facial recognition. Indeed, while people may find it humorous or galling when a toilet paper dispenser requires facial recognition, a police force’s use of facial recognition to identify protestors and quell local protests is a more weighty and controversial matter.
TV broadcasters may have a new way to reach the cordless generation: 5G. In July, the Federal Communications Commission (FCC) granted a six-month experimental license to a low-powertelevision network in Massachusetts to transmit video and other data one-way following the 5G protocol over a portion of the ultra high frequency (UHF) band via television towers.
If television broadcasters can meet some of consumers’ voracious demand for Internet video streaming using TV hardware and spectrum, it will free up some network bandwidth in spectrum previously used for two-way cellular signals and create new business opportunities. The FCC granted the SinclairBroadcasting Group a similar license in 2021, and Czech telecom CRA began broadcasting to mobile phones earlier this year as well.
Low-power television networks—which already target audiences that major broadcasters don’t—may be able to figure out how to make 5G work.