Chromatic dispersion compensation device

• US 20010021053A1
• Filed: 04/03/2001
• Published: 09/13/2001
• Est. Priority Date: 11/05/1999
• Status: Active Grant

• Current Assignee: Lumentum Operations, LLC (Lumentum Holdings Inc.)
• Original Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Inventors: Colbourne, Paul, Chen, Jyehong, Chang, Kok Wai, Tai, Kuochou
• Granted Patent: US 6,804,467 B2
• Time in Patent Office: Days
• US Class Current: 398/147
• CPC Class Codes: G02B 6/29358 Multiple beam interferometer external to a light guide, e.g. Fabry-Pérot, etalon, VIPA plate, OTDL plate, continuous interferometer, parallel plate resonator G02B6/29347, G02B6/29349, G02B6/2935, G02B6/29361 take precedence; resonator evanescently coupled to light guide G02B6/29335
• CPC Class Codes: G02B 6/29386 Interleaving or deinterleaving, i.e. separating or mixing subsets of optical signals, e.g. combining even and odd channels into a single optical signal
• CPC Class Codes: G02B 6/29394 Compensating wavelength dispersion G02B6/29376 takes precedence; dispersion compensated optical transmission systems H04B10/2507
• CPC Class Codes: H04B 10/25133 including a lumped electrical or optical dispersion compensator H04B10/2519, H04B10/2525 takes precedence

Abstract

A method and device is disclosed for dispersion compensation of an optical signal having periodic dispersion within a multi-channels system. For example interleaved optical channels often exhibit dispersion having a characteristic that is repeated in adjacent channels. By providing a periodic device that allows for polarization dependent routing of an interleaved signal to allow for multiple passes of said signal through a multi-cavity GT etalon, having a free-spectral range that corresponds to the channel spacing, the dispersion in the interleaved signal can be lessened and practically obviated or balanced to a desired level. This invention provides a device and method to achieve that end.

Claims

1. A dispersion compensation device for compensating a dispersion of an optical input beam, the device comprising:

polarization dependent beam routing means having an input port, for routing a polarized optical beam launched into the input port along a first path in one of two directions in dependence upon the polarization state of the polarized optical beam,

at least one multi-cavity etalon defining at least two resonant cavities, optically coupled to the routing means for receiving at least one optical beam from the routing means and for directing at least one reflected optical beam back to the routing means for the reflected light beam to follow a second path in the routing means; and

at least one polarization rotator for rotating the polarization of light in the optical path between the routing block and the etalon so that the at least one reflected light beam follows the second path in the routing means,

whereby the polarized light beam launched into the input port undergoes multiple reflections from the etalon to reduce dispersion of the optical input beam.

2. The device of

claim 1

further comprising beam directing means, optically coupled to the routing means, for receiving at least one beam from the routing means and for directing the at least one beam back to the routing means.

3. The device of

claim 2

wherein the directing means comprises a mirror.

4. The device of

claim 1

wherein the routing means comprises a birefringent material.

5. The device of

claim 1

wherein the routing means comprises a polarizing beam splitter.

9. The device of

claim 1

comprising two multi-cavity etalons optically coupled to the routing means whereby the polarized light beam launched into the input port undergoes multiple reflections from both etalons to reduce dispersion of the optical input beam.

11. The device as defined in

claim 2

, further comprising a second polarization rotator disposed in the optical path between the routing means and the directing means, for rotating the polarization of light beams passing between the routing beams and the directing means.

12. The device as defined in

claim 2

, wherein the beam directing means is a second multi-cavity etalon.

13. The dispersion compensation device as defined in

claim 1

, wherein the at least one multi-cavity etalon has a free spectral range in the range of 25 GHz to 400 GHz.

14. A dispersion compensation device as defined in

claim 13

, wherein the free spectral range of at least one cavity of the at least one multi-cavity etalon is equal to or an integer multiple of a channel spacing of the optical input beam or a channel spacing of the optical input beam being an integer multiple of the free spectral range of the at least one cavity of the at least one multi-cavity etalon.

15. A dispersion compensation device as defined in

claim 1

, further comprising means for tuning the at least one multi-cavity etalon by varying the optical path length of at least one of the cavities of the at least one multi-cavity etalon.

17. A dispersion compensation device as defined in

claim 1

, further comprising

means for tuning the multi-cavity etalon by varying the optical path length of at least one of the cavities of the first multi-cavity etalon by heating or cooling at least one cavity of the first multi-cavity etalon.

6. A dispersion compensation device for compensating a dispersion of an optical input beam, the device comprising:

a polarization diversity means for splitting an incoming beam of light into two orthogonally polarized sub-beams and for rotating the polarization of at least one of the polarized sub-beams to provide two sub-beams having a same polarization orientation,

polarization dependent beam routing means having at least one input port, for routing at least one polarized optical sub-beam launched into the input port along a first path in one of two directions in dependence upon the polarization state of the polarized optical sub-beam,

at least one multi-cavity etalon defining at least two resonant cavities, optically coupled to the routing means for receiving at least one optical sub-beam from the routing means and for directing at least one reflected optical sub-beam back to the routing means for the reflected optical sub-beam to follow a second path in the routing means; and

at least a first rotator for rotating the polarization of light in the optical path between the routing means and the etalon so that the at least one reflected optical sub-beam follows the second path in the routing means,

whereby the polarized optical sub-beam launched into the input port undergoes multiple reflections from the etalon to reduce dispersion of the optical input beam.

7. The device of

claim 6

wherein said routing means has at least one output port for said at least one optical sub-beam, and polarization diversity means coupled to said output port for recombining optical sub-beams into an output optical beam.

8. The device of

claim 7

wherein said output port and the input port are a single port and the device further comprises a circulator coupled to the single port.

10. The device of

claim 6

comprising two multi-cavity etalons optically coupled to the routing means for receiving at least one optical sub-beam from the routing means and for directing at least one reflected optical sub-beam back to the routing means for the reflected optical sub-beam to follow a second path in the routing means.

16. The device as defined in

claim 6

, wherein the polarization diversity means comprises a walk-off crystal.

18. A dispersion compensation device as defined in

claim 10

, wherein the two multi-cavity etalons have the same number of cavities.

19. A dispersion compensation device as defined in

claim 10

, wherein the two multi-cavity etalons have a different number of cavities.

20. A dispersion compensation device for compensating a dispersion of an optical input beam comprising:

input beam splitting means for spatially separating the input beam into two orthogonally polarized beams;

first polarization rotating means, optically coupled to the input beam splitting means, said first polarization rotating means for rotating the polarization of one of the two beams such that the two beams have the same polarization;

polarization dependent beam routing means, optically coupled to the first polarization rotating means, said polarization dependent beam routing means for routing the two beams on a first path for the two beams having a first polarization and on a second path for the two beams having a second polarization, orthogonal to the first polarization;

second polarization rotating means, optically coupled to the polarization dependent beam routing means, said second polarization rotating means for rotating the polarization of the two beams such that the two beams have the same polarization;

at least one multi-cavity etalon, optically coupled to the second polarization rotating means, said at least one multi-cavity etalon for receiving the two beams from the second polarization rotating means and for launching the two beams back to the second polarization rotating means, said multi-cavity etalon having at least one end face that is highly reflective and substantially not transmissive to light and at least two other faces that are partly reflective and partly transmissive, the one end face and the at least two other faces being separated from one another by predetermined gaps, the at least three faces forming at least two resonant cavities;

third polarization rotating means, optically coupled to the polarization dependent beam routing means, said third polarization rotating means for rotating the polarization of the two beams such that the two beams have the same polarization;

beam directing means, optically coupled to the third polarization rotating means, said beam directing means for receiving the two beams from the third polarization rotating means and for directing the two beams back to the third polarization rotating means;

fourth polarization rotating means, optically coupled to the polarization dependent beam routing means, said fourth polarization rotating means for rotating the polarization of one of the two beams such that the two beams have orthogonal polarizations; and

output beam combining means, optically coupled to the fourth polarization rotating means, said output beam combining means for spatially combining the two orthogonally polarized beams into an output beam;

whereby the two beams undergo multiple passes through the at least one multi-cavity etalon and thereby the dispersion correction of the two beams is increased.

21. A dispersion compensating system, containing at least two dispersion compensating devices, for compensating an overall dispersion of an optical input beam comprising:

input beam routing means for routing an input beam to a first dispersion compensating device, said first dispersion compensating device comprising;

input beam splitting means for spatially separating the input beam into two orthogonally polarized beams;

first polarization rotating means, optically coupled to the input beam splitting means, said first polarization rotating means for rotating the polarization of one of the two beams such that the two beams have the same polarization;

polarization dependent beam routing means, optically coupled to the first polarization rotating means, said polarization dependent beam routing means for routing the two beams on a first path for the two beams having a first polarization and on a second path for the two beams having a second polarization, orthogonal to the first polarization;

second polarization rotating means, optically coupled to the polarization dependent beam routing means, said second polarization rotating means for rotating the polarization of the two beams such that the two beams have the same polarization;

at least one multi-cavity etalon, optically coupled to the second polarization rotating means, said at least one multi-cavity etalon for receiving the two beams from the second polarization rotating means and for launching the two beams back to the second polarization rotating means, said multi-cavity etalon having at least one end face that is highly reflective and substantially not transmissive to light and at least two other faces that are partly reflective and partly transmissive, the one end face and the at least two other faces being separated from one another by predetermined gaps, the at least three faces forming at least two resonant cavities;

third polarization rotating means, optically coupled to the polarization dependent beam routing means, said third polarization rotating means for rotating the polarization of the two beams such that the two beams have the same polarization;

beam directing means, optically coupled to the third polarization rotating means, said beam directing means for receiving the two beams from the third polarization rotating means and for directing the two beams back to the third polarization rotating means;

fourth polarization rotating means, optically coupled to the polarization dependent beam routing means, said fourth polarization rotating means for rotating the polarization of one of the two beams such that the two beams have orthogonal polarizations;

output beam combining means, optically coupled to the fourth polarization rotating means, said output beam combining means for spatially combining the two orthogonally polarized beams into an output beam;

whereby the two beams undergo multiple passes through the at least one multi-cavity etalon and thereby the dispersion correction of the two beams is increased;

at least one intermediate beam routing means for routing an output beam, of at least a first dispersion compensating device, such that said output beam becomes an input beam of another dispersion compensating device, said another dispersion compensating device comprising;

input beam splitting means for spatially separating the input beam into two orthogonally polarized beams;

first polarization rotating means, optically coupled to the input beam splitting means, said first polarization rotating means for rotating the polarization of one of the two beams such that the two beams have the same polarization;

polarization dependent beam routing means, optically coupled to the first polarization rotating means, said polarization dependent beam routing means for routing the two beams on a first path for the two beams having a first polarization and on a second path for the two beams having a second polarization, orthogonal to the first polarization;

second polarization rotating means, optically coupled to the polarization dependent beam routing means, said second polarization rotating means for rotating the polarization of the two beams such that the two beams have the same polarization;

at least one multi-cavity etalon, optically coupled to the second polarization rotating means, said at least one multi-cavity etalon for receiving the two beams from the second polarization rotating means and for launching the two beams back to the second polarization rotating means, said multi-cavity etalon having at least one end face that is highly reflective and substantially not transmissive to light and at least two other faces that are partly reflective and partly transmissive, the one end face and the at least two other faces being separated from one another by predetermined gaps, the at least three faces forming at least two resonant cavities;

third polarization rotating means, optically coupled to the polarization dependent beam routing means, said third polarization rotating means for rotating the polarization of the two beams such that the two beams have the same polarization;

beam directing means, optically coupled to the third polarization rotating means, said beam directing means for receiving the two beams from the third polarization rotating means and for directing the two beams back to the third polarization rotating means;

fourth polarization rotating means, optically coupled to the polarization dependent beam routing means, said fourth polarization rotating means for rotating the polarization of one of the two beams such that the two beams have orthogonal polarizations;

output beam combining means, optically coupled to the fourth polarization rotating means, said output beam combining means for spatially combining the two orthogonally polarized beams into an output beam;

whereby the two beams undergo multiple passes through the at least one multi-cavity etalon and thereby the dispersion correction of the two beams is increased; and

output beam routing means, optically coupled to the last dispersion compensating device, said output beam routing means for routing an output beam of the last dispersion compensating device to an output port;

whereby the beam undergoes dispersion correction at each dispersion compensating device that results in balancing the compensation of the overall dispersion of an optical input beam to a predetermined value.

22. A method of dispersion compensation for simultaneously compensating for dispersion present within individual channels in a multi-channel signal, the method comprising:

providing a polarization dependent beam routing and directing means for routing and directing the multi-channel signal in a polarization dependent manner and at least one multi-cavity etalon optically coupled to said polarization dependent beam routing means; and

launching a multi-channel signal into said polarization dependent beam routing means to allow for multiple passes through said beam routing means and said multi-cavity etalon, and capturing a dispersion compensated multi-channel signal from said polarization dependent beam routing means.