Optical conversion system and method with multiple phase processing

• US 9,356,704 B1
• Filed: 08/09/2013
• Issued: 05/31/2016
• Est. Priority Date: 08/09/2013
• Status: Active Grant

• Current Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Rockwell Collins, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Chen, Wenlu, Zanoni, Raymond, King, Oliver S., Jepsen, Kim S., Cullen, Thomas J.
• Primary Examiner(s): Liu, Li
• Application Number:
  US13/963,899
• Time in Patent Office: 1,026 Days
• Field of Search: 398/158, 398/159, 398/161, 398202-209, 398212-214, 398/115, 398/116, 341/137, 341/155
• US Class Current: 1/1
• CPC Class Codes: G02F 7/00 Optical analogue/digital converters
• CPC Class Codes: H04B 10/61 Coherent receivers
• CPC Class Codes: H04B 10/63 Homodyne , i.e. coherent receivers where the local oscillator is locked in frequency and phase to the carrier signal

Abstract

A photonic processor can include a first input for a phase-modulated optical pulse signal, a second input for an optical reference signal, and a plurality of states. Each stage is configured to receive the phase-modulated optical pulse signal and a phase-delayed version of the optical reference signal. The phase-delayed version is phase-delayed in accordance with a phase position of the stage. Each stage is comprised of a reference path, a signal path, a coupler and a balanced photo detector. The coupler receives the phase-modulated optical pulse signal and provides as stage phase-modulated optical pulse signal to the signal path. The signal path is coupled to a first input of the balanced photo detector. The coupler also receives the phase-delayed version and provides a stage optical reference signal to the reference path. The reference path is coupled to a second input of the detector. The detector provides an electronic output signal corresponding to a phase relationship.

Claims

1. A photonic processor, comprising:

a first input configured to receive a phase-modulated optical pulse signal;

a second input configured to receive an optical reference signal;

a plurality of stages, each stage being configured to receive the phase-modulated optical pulse signal and a phase-delayed version of the optical reference signal, the phase-delayed version of the optical reference signal being phase-delayed in accordance with a phase position of the stage, wherein each stage is comprised of;

a reference coupler;

a phase delay;

a signal coupler;

a reference source path;

a signal source path;

a reference path;

a signal path, wherein the signal coupler is coupled to the signal path, to the signal source path and to a signal source path of the next stage, and wherein the reference coupler is coupled to the reference path, to the phase delay and to a reference source path of the next stage, wherein the phase delay is coupled to the reference coupler of the preceding stage;

a directional coupler coupled to the reference coupler and the signal coupler and used to interferometrically combine the phase-modulated optical pulse signal and the phase-delayed version of the optical reference signal for the stage; and

a balanced photo detector coupled to the directional coupler, wherein the balanced photo detector provides an electronic output signal corresponding to a phase relationship of the phase-delayed version of the optical reference signal and the phase-modulated optical pulse signal for the stage;

a first stage having a variable phase delay, the first stage being provided before the plurality of stages; and

a second stage being after the first stage and before the plurality of stages, wherein a reference signal received by an optical coupler in the second stage has a same phase as a reference signal received by an optical coupler in the first stage.

2. The photonic processor according to claim 1, wherein the phase delay in each stage provides an equal phase delay.

3. The photonic processor according to claim 2, wherein the balanced photo detector is at least one pair of photo diodes.

4. A photonic processor, comprising:

a first input configured to receive a phase-modulated optical pulse signal;

a second input configured to receive an optical reference signal; and

a first set of a plurality of stages, each stage of the first set being configured to receive the phase-modulated optical pulse signal and a phase-delayed version of the optical reference signal, the phase-delayed version of the optical reference signal being phase-delayed in accordance with a phase position of each stage among the first set of stages, wherein each stage of the first set is comprised of;

a reference path;

a signal path;

a directional coupler coupled to the reference path and the signal path and used to interferometrically combine the phase-modulated optical pulse signal and the phase-delayed version of the optical reference signal;

a balanced photo detector coupled to the directional coupler, wherein the balanced photo detector provides an electronic output signal corresponding to a phase relationship of the phase-delayed version of the optical reference signal and the phase-modulated optical pulse; and

a second set of a plurality of stages, each stage of the second set being configured to receive the phase-modulated optical pulse signal and a version of the optical reference signal, wherein each stage of the second set is comprised of;

a reference path;

a signal path;

a directional coupler coupled to the reference path and the signal path and used to interferometrically combine the phase-modulated optical pulse signal and the version of the optical reference signal; and

a balanced photo detector coupled to the directional coupler, wherein the balanced photo detector provides an electronic output signal corresponding to a phase relationship of the version of the optical reference signal and the phase-modulated optical pulse signal;

wherein the second set of stages comprises a first stage having a variable phase delay serving to eliminate spurious phase variations in the signal paths and the reference paths, and a second stage, wherein the version of the optical reference signal received by the second stage has a same phase as the version of the optical reference signal received by the first stage.

5. The photonic processor according to claim 4, wherein the second stage of the second set of stages is disposed after the first stage of the second set of stages and before the first set of stages.

6. A method of multi-phase processing, the method comprising:

receiving a phase-modulated optical pulse signal from a first optical coupler at a plurality of stages;

receiving a respective phase-delayed version of an optical reference signal from a second optical coupler at the plurality of stages, the respective phase-delayed version of the optical reference signal being phase-delayed in accordance with a phase position of the stage by an optical phase-delay element, wherein an input to the second optical coupler of at least one of the plurality of stages is coupled to an output of the phase-delay element of the preceding stage;

receiving a first reference signal at a first stage having a variable phase delay, the first stage being provided before the plurality of stages;

receiving a second reference signal at a second stage being after the first stage and before the plurality of stages, wherein the second reference signal is received by an optical coupler in the second stage and has a same phase as the first reference signal received by an optical coupler in the first stage;

combining and comparing the respective phase-delayed version of the optical reference signal with the phase-modulated optical pulse signal for the plurality of stages at each stage using a directional coupler and a pair of photo diodes in each stage; and

providing an electronic output signal corresponding to a phase relationship of the phase-delayed optical reference signal and the phase-modulated optical pulse signal at each stage of the plurality of stages.

7. The method according to claim 6, wherein the optical coupler at each stage provides the respective phase-delayed version for the stage to the directional coupler and provides an output phase delayed signal to a next stage, the output phase delayed signal having a lower power level than an output phase delayed signal from a preceding stage, wherein the power level of the respective phase-delayed version for each stage is equal.

8. The method according to claim 7, wherein the electronic output signal is provided as a thermometer output indicating a phase position of the phase-modulated optical pulse signal.

9. The method according to claim 6, wherein each optical phase delay element is equal in phase delay.

10. A multiphase photonic processor, comprising:

a phase modulator configured to receive an electronic radio frequency signal and an optical clock signal and to provide a phase-modulated optical signal on a first signal path, wherein the optical clock signal is provided on a second signal path;

a first directional coupler;

a first signal optical coupler for providing a first level of power of the phase-modulated optical signal to a first input of the first directional coupler;

a first reference optical coupler for providing a version of the optical clock signal to a second input of the first directional coupler;

a first balanced photodetector having a first input coupled to a first output of the first directional coupler and a second input coupled to a second output of the first directional coupler;

a second directional coupler;

a second signal optical coupler for providing a second level of power of the phase-modulated optical signal to a first input of the second directional coupler, the second level of power of the phase-modulated optical signal being approximately equal to the first level of power of the phase-modulated optical signal;

a second reference optical coupler for providing a delayed version of the optical clock signal to a second input of the second directional coupler;

a second balanced photodetector having a first input coupled to a first output of the second directional coupler and a second input coupled to a second output of the second directional coupler;

a third directional coupler;

a third signal optical coupler for providing a third level of power of the phase-modulated optical signal to a first input of the third directional coupler, the third level of power of the phase-modulated optical signal being greater than the first and second levels of power of the phase-modulated optical signal;

a third reference optical coupler for providing a delayed version of the optical clock signal to a second input of the third directional coupler;

a third balanced photodetector having a first input coupled to a first output of the third directional coupler and a second input coupled to a second output of the third directional coupler;

a first output associated with the first balanced photo detector;

a second output associated with the second balanced photo detector; and

a third output associated with the third balanced photodetector, wherein the first, second, and third outputs associated with the respective first, second, and third balanced photodetectors provide a thermometer electronic output signal corresponding to a phase relationship of the optical clock signal and the phase-modulated optical pulse signal.

11. The multiphase photonic processor according to claim 10, further comprising:

a delay element between the first reference optical coupler and the second reference optical coupler; and

a first trim adjust input for adjusting a delay provided by the delay element.

12. The multiphase photonic processor according to claim 10, further comprising:

a first delay element disposed between the first reference optical coupler and the second reference optical coupler.

13. The multiphase photonic processor according to claim 12, further comprising a trim adjust for the first delay element.

14. The multiphase photonic processor according to claim 13, wherein a second trim adjust is used to calibrate delay in the photonic processor.

15. The multiphase photonic processor according to claim 14, wherein the first delay element is coupled directly to the first reference optical coupler and the second reference optical coupler.

16. The multiphase photonic processor according to claim 14, wherein a variable delay is disposed before the first reference optical coupler and is used to calibrate for eliminating spurious phase variations.

17. The multiphase photonic processor according to claim 13 wherein the nth delay element is a thermo optic variable phase element with an embedded heater.

18. The multiphase photonic processor according to claim 12 wherein the first delay element is a thermo optic variable phase element with an embedded heater.

19. The photonic processor according to claim 10, further comprising wherein a reference signal received by the first reference optical coupler has a same phase as a reference signal received by a fourth reference signal optical coupler before the first reference signal optical coupler.

20. The multiphase photonic processor according to claim 10, wherein the delayed version of the optical clock signal for each reference optical coupler has a phase delay that is equal.