Optical frequency combs for low phase noise microwave generation

An optical frequency comb locked to a stable optical reference can serve as a source for microwave signals having very low close-to-carrier phase noise. This has recently been confirmed by comparing two independent systems, yielding an absolute phase noise of -104 dBc/Hz at 1 Hz offset from a 10 GHz carrier. The corresponding timing jitter is 760 attoseconds, integrated from 1 Hz to 1 MHz. Here we describe the system architecture, as well as technical and fundamental noise limitations.