Processing of signals with regenerative opto-electronic circuits

1. A method, comprising:

providing an opto-electronic oscillator device having a closed opto-electronic loop which comprises an electronic section and an optical section and forms a positive feedback loop, wherein the closed opto-electronic loop includes an input port to receive an input signal at an input signal frequency and an output port to output an output signal at an output signal frequency;

setting the closed opto-electronic loop at an initial state with a loop gain below an oscillation threshold when the input port does not receives the input signal;

injecting the input signal into the input port to operate the closed opto-electronic loop above the oscillation threshold to produce and sustain an oscillation signal in the closed opto-electronic loop; and

coupling a portion of the oscillation signal out of the closed opto-electronic loop to produce the output signal at the output port.

2. The method as in claim 1 , wherein the output signal frequency is equal to the input signal frequency.

3. The method as in claim 1 , wherein the closed opto-electronic loop has a nonlinear response to generate the output signal frequency that is different from the input signal frequency.

4. The method as in claim 3 , further comprising using a bandpass filter to filter the oscillation signal in the closed opto-electronic loop to transmit at the output signal frequency and to suppress signals at other frequencies.

5. The method as in claim 4 , wherein the bandpass filter has a center frequency that is a harmonic frequency of the input signal frequency.

6. The method as in claim 4 , wherein the bandpass filter has a center frequency which is equal to the input signal frequency divided by a factor of N where N is an integer greater than 1.

7. The method as in claim 1 , further comprising adjusting a phase delay of the closed opto-electronic loop to select the frequency of the oscillation signal to be at the output signal frequency.

8. The method as in claim 1 , wherein the input port is an optical port and the input signal is carried in an modulated optical carrier which is received by the optical port.

9. The method as in claim 1 , wherein the output port is an optical port which produces an output modulated optical carrier that carries the output signal.

10. A device, comprising:

a closed opto-electronic loop comprising an electronic section to carry an electronic signal, an optical section comprising an optical modulator to modulate an optical carrier to produce a modulated optical signal carrying the electronic signal, and a photodetector interconnecting the electronic section and the optical section to convert the optical signal into the electronic signal, wherein the electronic section is coupled to feed the electronic signal to control the optical modulator;

an input coupler coupled to the closed opto-electronic loop to receive and inject an input signal at an input signal frequency supported by the electronic portion; and

an output coupler coupled to the closed opto-electronic loop to couple an output signal out of the closed opto-electronic loop at an output signal frequency supported by the electronic portion and different from the input signal frequency,

wherein the closed opto-electronic loop forms a positive feedback loop and has a nonlinear response to produce at least one nonlinear signal component at the output signal frequency.

11. The device as in claim 10 , wherein the electronic section of the closed opto-electronic loop comprises a bandpass filter to transmit at the output signal frequency and suppress signals at the input signal frequency and frequencies different from the output signal frequency.

12. The device as in claim 11 , wherein the bandpass filter comprises:

an input port coupled to the electronic section to receive an input microwave or RF signal from the electronic section;

a laser to produce a continuous-wave laser beam;

a first optical path to receive a first portion of the laser beam;

a second optical path to receive a second portion of the laser beam, the second optical path comprising:

an optical modulator to modulate the second portion in response to the input signal to produce a modulated optical beam that carries the input signal, and

a tunable optical filter to filter the modulated optical beam to select at least one spectral component in the input signal while rejecting other spectral components and to output a filtered modulated optical beam that carries the at least one selected spectral component at the output signal frequency, the tunable optical filter comprising two optical resonators that are optically coupled to produce a filter function of at least a second order;

a tuning control unit to tune at least one of the two optical resonators to change a frequency of the at least one selected spectral component;

an optical detector to combine the first portion from the first optical path and the filtered modulated optical beam from the second optical path and to produce a filtered output signal comprising the selected spectral component; and

an output port coupled to the electronic section to output the filtered output signal into the electronic section.

13. The device as in claim 10 , wherein the electronic section of the closed opto-electronic loop comprises a phase shifter which changes a phase of the electronic signal applied to the optical modulator.

14. The device as in claim 10 , wherein the input coupler is an electronic signal coupler.

15. The device as in claim 10 , wherein the input coupler is an optical coupler which receives an input optical signal that is optically modulated to carry the input signal.

16. The device as in claim 10 , wherein the output coupler is an electronic signal coupler.

17. The device as in claim 10 , wherein the output coupler is an optical coupler which couples light out of the optical section of the closed opto-electronic loop that is optically modulated to carry the output signal.

18. The device as in claim 10 , wherein the optical section of the closed opto-electronic loop comprises a laser resonator which produces the light in the optical section and the optical modulator resides inside the laser resonator.

19. A device, comprising:

a closed opto-electronic loop comprising an electronic section to carry an electronic signal, an optical section comprising an optical modulator to modulate an optical carrier to produce a modulated optical signal carrying the electronic signal, and a photodetector interconnecting the electronic section and the optical section to convert the optical signal into the electronic signal, wherein the electronic section is coupled to feed the electronic signal to control the optical modulator;

an input coupler coupled to the closed opto-electronic loop to receive and inject an input signal at an input signal frequency supported by the electronic portion; and

an input coupler coupled to the closed opto-electronic loop to couple an output signal out of the closed opto-electronic loop at an output signal frequency supported by the electronic portion and different from the input signal frequency,

wherein the closed opto-electronic loop forms a positive feedback loop and comprises a bandpass filter to transmit at the output signal frequency and suppress signals at the input signal frequency and frequencies different from the output signal frequency.

20. The device as in claim 19 , wherein the bandpass filter comprises:

an input port coupled to the electronic section to receive an input microwave or RF signal;

a tunable laser to produce a continuous-wave laser beam and to tune a laser frequency of the laser beam;

a first optical path to receive a first portion of the laser beam;

a second optical path to receive a second portion of the laser beam, the second optical path comprising:

an optical modulator to modulate the second portion in response to the input signal to produce a modulated optical beam that carries the input signal, and

an optical filter to filter the modulated optical beam to select at least one spectral component in the input signal while rejecting other spectral components and to output a filtered modulated optical beam that carries the at least one selected spectral component;

a tuning control unit to tune the laser frequency of the tunable laser to change a frequency of the at least one selected spectral component;

an optical detector to combine the first portion from the first optical path and the filtered modulated optical beam from the second optical path and to produce a filtered output signal comprising the at least one selected spectral component; and

an output port coupled to the electronic section to output the filtered output signal into the electronic section.