Optical interleaver

1. An optical device, comprising:

an interleaver/deinterleaver having at least one polarization transforming element coupled to a first passive thermal compensator and a second passive thermal compensator, the thermal compensators configured to substantially compensate, respectively, for first order and second order temperature-induced frequency drift of the at least one polarization transforming element over a desired temperature range.

2. The optical device of claim 1 , wherein at least one thermal compensator includes at least one birefringent element.

3. The optical device of claim 2 , wherein the at least one polarization transforming element includes at least one birefringent element.

4. The optical device of claim 3 , wherein the at least one birefringent element of the polarization transforming element has a fast axis, and the at least one birefringent element of the thermal compensator has a fast axis, and the fast axes are parallel.

5. The optical device of claim 3 , wherein the at least one birefringent element of the polarization transforming element has a fast axis, and the at least one birefringent element of the thermal compensator has a fast axis, and the fast axes are orthogonal.

6. The optical device of claim 3 , wherein the optical device satisfies a condition of athermalization given by:

L

1

⁢

ⅆ

Δ

⁢

⁢

n

1

ⅆ

T

+

L

2

⁢

ⅆ

Δ

⁢

⁢

n

2

ⅆ

T

+

Δ

⁢

⁢

n

1

⁢

L

1

⁢

α

1

+

Δ

⁢

⁢

n

2

⁢

L

2

⁢

α

2

=

O

where L 1 is a length of the at least one birefringent element of the polarization transforming element, L 2 is a length of the at least one birefringent element of the thermal compensator, Δn 1 is the birefringence of the at least one birefringent element of the polarization transforming element, Δn 2 is the birefringence of the at least one birefringent element of the thermal compensator, a 1 is an expansion coefficient of the at least one birefringent element of the polarization transforming element, and a 2 is the expansion coefficient of the at least one birefringent element of the thermal compensator.

7. The optical device of claim 2 , wherein the at least one birefringent element of the passive thermal compensator is chosen from the group consisting essentially of rutile, calcite, lithium niobate, and yttrium vanadate.

8. The optical device of claim 1 , wherein an interleaved/deinterleaved optical signal includes channels having a spacing in the range of approximately 12.5 ghz to approximately 400 ghz when outputted from the optical device.

9. The optical device of claim 8 , wherein the temperature induced frequency drift is in the range of approximately −2.5 ghz to approximately +2.5 ghz.

10. An optical device, comprising:

an interleaver/deinterleaver having at least one polarization transforming element directly attached to at least one passive thermal compensator, wherein an optical signal which traverses the optical device undergoes substantially no temperature-induced frequency drift over a desired temperature range and wherein the thermal compensator includes at least two birefringent elements that are directly attached to one another and one of the at least two birefringent elements is directly attached to the birefringent element of the polarization transforming element.

11. The optical device of claim 10 , wherein the temperature induced frequency drift is in the range of approximately −2.5 GHz to approximately +2.5 GHz.

12. The optical device of claim 10 , wherein the desired temperature range is approximately −10° C. to approximately +70° C.

13. The optical device of claim 10 , wherein the optical signal includes mxn channels when inputted into the optical device, and includes n/m output channels when outputted from the optical device, wherein m and n are integers.

14. The optical device of claim 13 , wherein m=2.

15. A method of interleaving/deinterleaving an optical signal, the method comprising:

providing an interleaver/deinterleaver having at least one polarization transforming element directly attached to at least one passive thermal compensator, wherein the passive thermal compensator comprises at least two birefringent elements directly attached to one another and one of the at least two birefringent elements is directly attached to the polarization transforming element; and

traversing the interleaver/deinterleaver with an optical signal, wherein the optical signal undergoes substantially no temperature-induced frequency drift over a desired temperature range.

16. The method as recited in claim 15 , wherein the desired temperature range is approximately −10° C. to approximately +70° C.

17. A method of interleaving/deinterleaving an optical signal, the method comprising:

providing an interleaver/deinterleaver having at least one polarization transforming element coupled to a first passive thermal compensator and a second passive thermal compensator; and

traversing the interleaver/deinterleaver with an optical signal, wherein the thermal compensators are configured to substantially compensate, respectively, for first order and second order temperature-induced frequency drift of the at least one polarization transforming element over a desired temperature range.

18. The method of claim 17 , wherein at least one thermal compensator includes at least one birefringent element.

19. The method of claim 18 , wherein the at least one polarization transforming element includes at least one birefringent element.

20. The method of claim 19 , wherein the at least one birefringent element of the polarization transforming element has a fast axis; the at least one birefringent element of the thermal compensator has a fast axis, and the fast axes are orthogonal.

21. The method of claim 19 , wherein the at least one birefringent element of the polarization transforming element has a fast axis, and the at least one birefringent element of the thermal compensator has a fast axis, and the fast axes are parallel.