Tunable opto-electronic oscillator having optical resonator filter operating at selected modulation sideband

摘要

Opto-electronic oscillator (OEO) devices include an optical resonator filter to block the strong laser light at the laser carrier frequency from entering the optical resonator filter and to select one of the weak modulation sidebands, which is in resonance with the optical resonator filter, to be coupled into the optical resonator filter. The laser light at the laser carrier frequency and other modulation sidebands bypass the optical resonator filter to reach a fast photodetector. The laser light in the selected modulation sideband in the optical resonator filter is then coupled out to mix with the laser light at the laser carrier frequency and other modulation sidebands at the fast photodetector to produce the detector output as the input to the electrical part of the opto-electronic loop to produce the OEO oscillation.

主权项

1. An opto-electronic oscillator device, comprising:
a laser to emit laser light at a laser carrier frequency; an optical modulator that receives the laser light from the laser and modulates the received laser light, under a control of and in response to a modulation control signal, to produce modulated laser light having spectral components at the laser carrier frequency and modulation sidebands at frequencies different from the laser carrier frequency; an optical resonator filter positioned to receive the modulated laser light at a selected modulation sideband in resonance with an optical mode of the optical resonator filter to selectively receive and output filtered laser light at the selected modulation sideband while blocking laser light at the laser carrier frequency and other modulation sidebands from entering the optical resonator filter; an optical detector coupled to receive the filtered laser light at the selected modulation sideband and the laser light at the laser carrier frequency and other modulation sidebands to produce an electrical detector signal; and a feedback electronic circuit coupled between the optical detector and the optical modulator to amplify the electrical detector signal and to produce an electrical feedback signal as the modulation control signal that is fed into the optical modulator to produce a total signal gain greater than a total signal loss in a closed opto-electronic loop that includes (1) an optical section including the optical modulator, the optical resonator filter and the optical detector and (2) an electronic section including the optical detector and the feedback electronic circuit to sustain an oscillation in the closed opto-electronic loop, wherein the optical section and the electronic section are configured to render an oscillation frequency of the oscillation to be independent of a free spectral range of the optical resonator filter.