Radiometer based on nonlinear microwave to optical conversion in a resonator.

The ATESCA (Ambient Temperature Extremely Sensitive Radiometer for CubeSat Applications) project seeks to advance radiometer technology by achieving highly sensitive microwave detection for space-based applications, such as radio astronomy and Earth observation, without the need for cryogenic cooling of the detector. This project is particularly focused on improving the detection of microwave radiation from the ozone of earths atmosphere and from the cosmic microwave background (CMB).ATESCA radiometers utilize a nonlinear optical upconversion process to transfer weak microwave signals into the optical domain. This process is intrinsically noiseless, and it has been shown theoretically that a good signal to noise ratio can be achieved even when the whole setup is sitting at room temperature (opposed to direct detection of the microwave radiation).The nonlinear upconversion process is intrinsically weak. Hence the team plans to employ whispering gallery mode resonators, which support resonances in both optical and microwave domains to significantly improve conversion efficiency. It has been shown theoretically that with the planned implementation, a photon conversion efficiency from the microwave (> 100GHz) to the optical domain of 1% can be achieved. This will enable the proposed radiometer with high sensitivity but would also be interesting for future quantum technology.This is a planned collaboration between a group in Madrid, Spain (UC3M) and Dunedin, New Zealand (UoO). The researcher will demonstrate the proposed conversion efficiency and hence sensitivity on a benchtop experiment and, afterwards, will implement the system into two actual payloads for CubeSat missions to demonstrate the radiometer.