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ESAâs CHEOPS Just Launched. Weâre About to Learn a LOT More About Exoplanets
The CHEOPS mission is underway. On December 18th, the exoplanet-studying spacecraft launched from Europeâs Spaceport in Kourou, French Guiana aboard a Soyuz-Fregat rocket. Initial signals from CHEOPS show that the launch was a success.
CHEOPS stands for the Characterizing Exoplanet Satellite. Itâs a partnership between ESA and Switzerland, with 10 other EU states contributing. Its mission is not to find more exoplanets, but to study the ones we already know of.
Itâll watch as these exoplanets transit in front of the star, the same way weâve found most of the exoplanets weâve discovered to date. But CHEOPS will be focusing on the dips in starlight with a specific intent: to find the planetsâ size.
Space-time metasurface makes light reflect only in one direction
Light propagation is usually reciprocal, meaning that the trajectory of light travelling in one direction is identical to that of light travelling in the opposite direction. Breaking reciprocity can make light propagate only in one direction. Optical components that support such unidirectional flow of light, for example isolators and circulators, are indispensable building blocks in many modern laser and communication systems. They are currently almost exclusively based on the magneto-optic effect, making the devices bulky and difficult for integration. A magnetic-free route to achieve nonreciprocal light propagation in many optical applications is therefore in great demand.
Recently, scientists developed a new type of optical metasurface with which phase modulation in both space and time is imposed on the reflected light, leading to different paths for the forward and backward light propagation. For the first time, nonreciprocal light propagation in free space was realized experimentally at optical frequencies with an ultrathin component.
âThis is the first optical metasurface with controllable ultrafast time-varying properties that is capable of breaking optical reciprocity without a bulky magnet,â said Xingjie Ni, the Charles H. Fetter Assistant Professor in Department of Electrical Engineering at the Pennsylvania State University. The results were published this week in Light: Science and Applications.