Coupled and non-coupled opto-electronic oscillators with enhanced performance

1. A device, comprising:

a ring laser comprising an optical ring which comprises at least one optical gain medium operable to produce laser light;

an optical modulator coupled in the optical ring and operable to modulate the laser light in response to a control signal to produce a modulated laser beam;

an opto-electronic feedback loop comprising an optical portion operable to receive a portion of light from the ring laser, a photodetector operable to convert the received portion of light into a detector signal, and an electrical portion operable to produce the control signal from the detector signal; and

a dispersion compensation element coupled in the optical ring and operable to compensate for optical dispersion in the optical ring.

2. The device as in claim 1 , wherein the dispersion compensation element comprises a dispersion compensated fiber.

3. The device as in claim 1 , wherein the dispersion compensation element comprises a dispersion shifted fiber.

4. The device as in claim 1 , wherein the dispersion compensation element comprises a fiber Bragg grating.

5. The device as in claim 1 , further comprising a polarization control unit coupled in the optical ring and operable to control a polarization of the laser light.

6. The device as in claim 1 , wherein the optical ring includes polarization maintaining fiber which controls a polarization of the laser light.

7. The device in claim 1 , further comprising an optical resonator in the optical ring.

8. The device as in claim 1 , further comprising:

an optical polarization beam splitter coupled in the optical ring to direct light received from the optical ring into a first light beam;

a 45-degree Faraday rotator to receive and transmits the first light beam;

a reflective unit to reflect the first light beam transmitted through the Faraday rotator back to the optical polarization beam splitter by transmitting through the Faraday rotator for a second time; and

a fiber delay line between an optical path between the optical polarization beam splitter and the reflective unit to transport light,

wherein the optical polarization beam splitter is coupled to the optical ring to direct light reflected back from the reflective unit into the optical ring.

9. The device as in claim 8 , wherein the reflective unit is a mirror.

10. The device as in claim 8 , wherein the reflective unit comprises a fiber Bragg grating.

11. The device as in claim 1 , further comprising:

an optical splitter to split the received portion of light from the ring laser into a first beam and a second beam;

a first optical delay path to receive the first beam;

a second optical delay path to receive the second beam, wherein the first and second optical paths have different optical delays,

wherein the photodetector is coupled to receive the first and second beams, at orthogonal polarizations, from the first and second optical delay paths to produce the detector signal.

12. A method, comprising:

selecting a length of an optical ring that generates laser light in a coupled opto-electronic oscillator (COEO) which further comprises an opto-electronic feedback loop coupled to the ring to produce a desired separation between a carrier frequency generated by the COEO and a first spurious mode generated by the COEO; and

using a dispersion compensation element in the ring to negate optical dispersion in the ring to reduce phase noise of the COEO below an acceptable level.

13. The method as in claim 12 , further comprising:

controlling a polarization of the laser light in the optical ring.

14. A device, comprising:

an optical loop which comprises at least one optical gain medium operable to produce laser light;

an optical modulator coupled in the optical loop and operable to modulate the laser light in response to a control signal to produce modulated laser light;

an opto-electronic feedback loop comprising an optical portion operable to receive a portion of the modulated laser light from the optical loop, a photodetector operable to convert the received portion into a detector signal, and an electrical portion operable to produce the control signal from the detector signal;

an optical polarization beam splitter coupled in the optical loop to direct light received from the optical loop into a first light beam;

a 45-degree Faraday rotator to receive and transmits the first light beam;

a reflective unit to reflect the first light beam transmitted through the Faraday rotator back to the optical polarization beam splitter by transmitting through the Faraday rotator for a second time; and

a fiber delay line between an optical path between the optical polarization beam splitter and the reflective unit to transport light,

wherein the optical polarization beam splitter is coupled to the optical loop to direct light reflected back from the reflective unit into the optical loop.

15. The device as in claim 14 , wherein the optical loop is formed from polarization maintaining fiber.

16. The device as in claim 14 , further comprising:

an optical splitter to split the received portion of the laser light from the optical loop into a first beam and a second beam;

a first optical delay path to receive the first beam;

a second optical delay path to receive the second beam, wherein the first and second optical paths have different optical delays,

wherein the photodetector is coupled to receive the first and second beams, at orthogonal polarizations, from the first and second optical delay paths to produce the detector signal.

17. A device, comprising:

a laser to produce CW laser light;

an optical modulator to modulate the CW laser light to produce modulated laser light in response to an electrical control signal;

an optical splitter to receive at least a portion of the modulated laser light and to split the received portion into a first beam and a second beam;

a first optical delay path to receive the first beam;

a second optical delay path to receive the second beam, wherein the first and second optical paths have different optical delays;

a photodetector coupled to receive the first and second beams, at orthogonal polarizations, from the first and second optical delay paths to produce a detector signal; and

an electrical section operable to receive and process the detector signal to produce the electrical control signal,

wherein the electrical section, the optical modulator, the optical splitter, the first and second optical delay paths, and the photodetector form a part of a closed opto-electronic feedback loop that is operable to have a loop gain greater than the loop loss and to generate an oscillation at a modulation frequency of the optical modulator.