Opto-Electronic Oscillator With Quality Multiplier

This paper presents an opto-electronic oscillator (OEO) with a regenerative electronic circuit that increases the selectivity of the oscillator's loop. The regenerative circuit works as a multiplier of the bandpass filter's quality factor. This makes it possible to realize very narrow bandwidths and thus increase the side-mode suppression ratio of the OEO. Our measurements show an almost 20-dB increase in the suppression of the side modes at the expense of an increase in the phase noise by approximately 4 dB at a 1-kHz frequency offset.