NIST researchers have developed a new method for generating extremely low-noise microwave signals using femtosecond-laser frequency combs. The technique, called “optical frequency division” (OFD), involves using a stable optical oscillator to create a pulse train that, when photodetected, generates electronic pulse trains with high spectral purity harmonics.
The resulting microwave signals have phase noise 40 dB lower than the best room-temperature electronic oscillators, with 10GHz signals achieving absolute phase noise less than −100 dBc/Hz. This breakthrough could enable significant improvements in radar, sensing, high-speed signal processing, communications, navigation, and data encryption technologies.
The research builds on the principles of femtosecond-laser frequency combs, which can generate thousands to millions of phase-coherent modes. By extending these principles to generate arbitrary waveform signals, the researchers have opened up new possibilities for agile optical signal processing and control of electromagnetic waveforms.
Source: https://www.nist.gov/programs-projects/optical-and-microwave-waveform-synthesis
Keywords: Phase noise, Femtosecond-laser frequency combs, Microwave signals, Optical frequency division, Photodetection
