LAUSR

An opto-electronic oscillator (OEO) scheme which operates at "chirp oscillation" mode and generates low-phase-noise, frequency-swept microwave is proposed and experimentally demonstrated. This frequency-swept OEO is achieved by embedding a rapidly frequency-scanning microwave filter in an opto-electronic cavity. The filter has fixed passband while its center frequency scans rapidly and periodically at cavity round-trip time, covering a large frequency range (~GHz). Experimentally, the generated frequency-swept microwave is linear frequency-modulated continuous wave (FMCW) which centers at 7 GHz with 1-GHz bandwidth. Its instantaneous frequency varies linearly from 6.5 GHz to 7.5 GHz, back and forth, in a period of 12.8 μs, resulting in a frequency scanning rate of ~156 MHz/μs. The single-side-band (SSB) noise of the generated FMCW is -104 dBc/Hz at 10 kHz offset frequency, which is much lower than that from a commercial electronic arbitrary waveform generator (E-AWG). Improvement as large as 23 dB is experimentally reported.