Optical frequency combs can link frequencies in the microwave domain to high-purity laser emissions, yielding unprecedented precision in time-keeping and metrology. Now EPFL scientists and their colleagues have generated variable low-noise microwave signals by building variable microwave gears with two compact optical frequency combs.
Low-noise microwave signals are of critical importance in numerous applications such as high-speed telecommunication and ultrafast data processing. Conventionally, such signals are generated with bulky and delicate microwave oscillators that are not suitable for out-of-door applications. But recently, physicists have been exploring a possible alternative: high-quality microwave generation using optical microresonator frequency combs.
Relying on the high optical frequency and spectral purity of laser fields, optical microresonators can generate low-noise microwaves in a compact and efficient manner. But a microresonator can usually only generate microwaves with very limited frequency tunability. The reason is that the microwave frequency depends on the resonator’s size, which is not itself highly tunable.
Source: “Microcomb-injected pulsed lasers as variable microwave gears”, Wenlw Weng, Nik Papageorgiou, EPFL News