Multi-Channel Dispersion Compensator

• US 20090116786A1
• Filed: 11/02/2007
• Published: 05/07/2009
• Est. Priority Date: 11/02/2007
• Status: Active Grant

• Current Assignee: Infinera Corp.
• Original Assignee: Infinera Corp.
• Inventors: Little, Brent E., Chen, Wei
• Granted Patent: US 8,488,922 B2
• Time in Patent Office: Days
• US Class Current: 385/27
• CPC Class Codes: G02B 6/29343 Cascade of loop resonators
• CPC Class Codes: G02B 6/29352 in a light guide
• CPC Class Codes: G02B 6/29353 with a wavelength selective element in at least one light guide interferometer arm, e.g. grating, interference filter, resonator
• CPC Class Codes: G02B 6/29355 Cascade arrangement of interferometers
• CPC Class Codes: G02B 6/29394 Compensating wavelength dispersion G02B6/29376 takes precedence; dispersion compensated optical transmission systems H04B10/2507
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35

Abstract

A multi-channel dispersion compensator comprising an optical signal waveguide that forms an input end for receiving an optical signal and an output end for providing a filtered optical signal. The multi-channel dispersion compensator also includes a series of closed-loop resonators providing frequency delay to at least one channel of the optical signal. The optical signal waveguide and each closed-loop resonator form a tunable coupler having a coupling value. The coupling value for each tunable coupler is selected to minimize constant dispersion and linear slope dispersion of the optical signal. Methods of fabrication and use are also described.

Claims

1. A multi-channel dispersion compensator, comprising:

an optical signal waveguide forming an input end for receiving an optical signal and an output end for providing a filtered optical signal; and

,

a series of closed-loop resonators constructed to provide frequency delay to at least two channels of the optical signal, wherein the optical signal waveguide and each closed-loop resonator form a tunable coupler having a coupling value, the coupling value for each tunable coupler being selected so as to minimize constant dispersion and linear slope dispersion of the optical signal.

2. The multi-channel dispersion compensator of claim 1, further comprising a tuning element located adjacent to the optical signal waveguide.

3. The multi-channel dispersion compensator of claim 2, further comprising a controller selectively providing a signal to adjust power dissipation of the tuning element.

4. The multi-channel dispersion compensator of claim 3, wherein the controller selectively provides the signal based on bit rate error.

5. The multi-channel dispersion compensator of claim 4, wherein the controller analyzes bit rate error provided by an external source.

6. The multi-channel dispersion compensator of claim 2, wherein the tuning element is a thermal device placed in thermal communication with the optical signal waveguide.

7. The multi-channel dispersion compensator of claim 1, further comprising at least one ring resonator adjacent to the optical signal waveguide and forming at least one ring-assisted interferometer.

8. The multi-channel dispersion compensator of claim 7, further comprising a first tuning element located adjacent to the optical signal waveguide.

9. The multi-channel dispersion compensator of claim 8, further comprising a second tuning element located adjacent to the ring resonator.

10. The multi-channel dispersion compensator of claim 1, wherein the coupling value is selected so as to minimize high order dispersion.

11. The multi-channel dispersion compensator of claim 1, wherein the optical signal waveguide is bidirectional.

12. A multi-channel dispersion compensator for adjusting constant dispersion and linear dispersion of an optical signal, comprising:

an optical signal waveguide having an input end for receiving the optical signal and an output end for providing a filtered optical signal;

at least one closed loop resonator constructed to provide frequency delay to at least two channels of the optical signal; and

,

a tunable coupler coupling the optical signal between the optical signal waveguide and the closed loop resonator and providing filtered optical signals to the output end of the optical signal waveguide, the tunable coupler adjustably tuning the optical signal to alter linear slope dispersion and constant dispersion of the optical signal.

13. The multi-channel dispersion compensator of claim 12, wherein the tunable coupler comprises:

a first directional coupler having a first arm disposed on the optical signal waveguide and a second arm disposed on the closed loop resonator;

a second directional coupler having a first arm disposed on the optical signal waveguide and a second arm disposed on the closed loop resonator; and

,

a differential phase cell formed between the first directional coupler and the second directional coupler, the differential phase cell having a first arm disposed on the optical signal waveguide having a first length (L₁) and a second arm disposed on the closed loop resonator having a second length (L₂), wherein (L₁≠

L₂).

14. The multi-channel dispersion compensator of claim 13, wherein the tunable coupler further comprises a tuning element adjacent the differential phase cell.

15. The multi-channel dispersion compensator of claim 14, wherein the tuning element is a thermal device in thermal communication with at least a portion of the optical filter.

16. The multi-channel dispersion compensator of claim 12, wherein the tunable coupler comprises:

at least three directional couplers with each directional coupler having a first arm disposed on the optical signal waveguide and a second arm disposed on the closed loop resonator;

at least two differential phase cells with each differential phase cell connecting adjacent directional couplers, each differential phase cell having a first arm disposed on the optical signal waveguide and a second arm disposed on the closed loop resonator, the first arm having a first length (L₁) and the second arm having a second length (L₂), wherein (L₁≠

L₂) for at least one differential phase cell.

17. The multi-channel dispersion compensator of claim 12, wherein the tunable coupler is capable of adjustably tuning the optical signal to alter high order dispersion.

18. The multi-channel dispersion compensator of claim 12, further comprising at least one ring resonator adjacent the optical signal waveguide and forming at least one ring-assisted interferometer.

19. The multi-channel dispersion compensator of claim 18, further comprising at least one tuning element adjacent the optical signal waveguide.

20. The multi-channel dispersion compensator of claim 19, further comprising a second tuning element adjacent the ring resonator.

21. The multi-channel dispersion compensator of claim 20, further comprising a controller selectively altering power dissipation of the tuning elements based on bit rate error.

22. The multi-channel dispersion compensator of claim 12, wherein the optical signal waveguide is bidirectional.

23. A method of fabricating a multi-channel dispersion compensator, having an optical signal waveguide adjacent a closed-loop resonator forming a tunable coupler, the method comprising the steps of:

calculating a wavelength-dependent coupling value for the tunable coupler; and

,

forming an image in a photoresist layer on a core material constructed of optically transparent material, the image having a predetermined pattern indicative of an optical signal waveguide positioned adjacent to a closed-loop resonator forming a tunable coupler, the tunable coupler being designed for the wavelength-dependent coupling value;

developing the photoresist layer to form a mask having a predetermined pattern of the multi-channel dispersion compensator; and

,

transferring the predetermined pattern of the multi-channel dispersion compensator into the core material.

24. A planar lightwave circuit, comprising:

a substrate;

a cladding on the substrate;

a multi-channel dispersion compensator on the cladding comprising;

a first directional coupler having an input end, an output end, and a coupling region;

a second directional coupler having an input end, an output end, and a coupling region, wherein the output end of the second directional coupler and the input end of the first directional coupler are connected to form a closed-loop resonator; and

,

a differential phase cell connecting the output end of the first directional coupler with the input end of the second directional coupler, the differential phase cell having a first arm with a first length (L₁) and a second arm with a second length (L₂), wherein (L₁≠

L₂).

25. A method of altering constant dispersion and linear slope dispersion of an optical signal propagating through an optical signal waveguide coupled to a closed ring resonator forming a tunable coupler, the method comprising the steps of:

tuning a tuning element of the tunable coupler to alter constant dispersion and linear slope dispersion of the optical signal, the tunable coupler comprising;

a first directional coupler having an input end, an output end, and a coupling region;

a second directional coupler having an input end, an output end, and a coupling region, wherein the output end of the second directional coupler and the input end of the first directional coupler are connected to form a closed-loop resonator;

a differential phase cell between the first directional coupler and the second directional coupler, the differential phase cell having a first arm with a first length (L₁) and a second arm with a second length (L₂), wherein (L₁≠

L₂); and

,

a tuning element adjacent to one of the arms of the differential phase cell, the tuning element capable of shifting the optical phase of the optical signal.