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

A method for generating an oscillation signal, comprising:

• operating an optical modulator to respond to a modulation control signal to perform optical modulation on laser light at a laser carrier frequency to produce modulated laser light having a spectral component at the laser carrier frequency and spectral components at modulation sidebands at frequencies different from the laser carrier frequency;
• coupling light at a selected modulation sideband in the modulated laser light into an optical resonator filter which is in optical resonance with the selected modulation sideband to produce filtered laser light at a frequency of the selected modulation sideband while blocking laser light at the laser carrier frequency and laser light at other modulation sidebands from to entering the optical resonator filter;
• operating an optical detector to receive the filtered laser light at the selected modulation sideband and laser light at the laser carrier frequency and other modulation sidebands to produce an electrical detector signal;
• and
• operating a feedback electronic circuit to process the electrical detector signal to produce the modulation control signal that is fed into the optical modulator, wherein the processing of the electrical detector signal 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.

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 at least a phase of the received laser light, in response to a modulation control signal, to produce modulated laser light having strong laser light at the laser carrier frequency and weak laser to light at modulation sidebands at frequencies different from the laser carrier frequency;
• an optical whispering gallery mode resonator filter positioned to receive the modulated laser light from the optical modulator and configured to be in optical resonance with a selected modulation sideband of the modulated laser light 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 whispering gallery mode resonator filter;
• an optical detector coupled to receive the filtered laser light at the selected modulation sideband and 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 include an amplifier that amplifies the electrical detector signal and a phase rotator that adjusts a phase of the electrical detector signal to produce the modulation control signal that is fed into the optical modulator,
• wherein the feedback electronic circuit is configured 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, and
• wherein the laser or the optical whispering gallery mode resonator filter is tunable in frequency to tune an oscillation frequency of the oscillation in the closed opto-electronic loop.