Fiber optic cross connect with transparent substrate

• US 6,396,973 B1
• Filed: 04/14/2000
• Issued: 05/28/2002
• Est. Priority Date: 04/14/2000
• Status: Expired due to Fees

• Current Assignee: C Speed, LLC
• Original Assignee: C Speed, LLC
• Inventors: Bhattarai, Amal Ranjan, Hagelin, Paul Merritt
• Primary Examiner(s): Schuberg, Darren
• Assistant Examiner(s): ASSAF, FAYEZ G
• Application Number:
  US09/549,789
• Time in Patent Office: 774 Days
• Field of Search: 385/17,18,19 359/223,224,872,873
• US Class Current: 385/17
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3556 NxM switch, i.e. regular arrays of switches elements of matrix type constellation
• CPC Class Codes: G02B 6/356 in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001
• CPC Class Codes: G02B 6/3582 Housing means or package or arranging details of the switching elements, e.g. for thermal isolation
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0026 using free space propagation (e.g. lenses, mirrors)
• CPC Class Codes: Y10S 359/904 Micromirror

Abstract

The present invention provides an improved fiber optic cross connect (OXC) package. The OXC includes a substrate, where light beams may travel through the substrate; a plurality of optical fibers optically coupled to a first surface of the substrate; and a micromirror array coupled to a second surface of the substrate. In the preferred embodiment, this substrate is optically transparent to the wavelengths of interest. The light beams enter the substrate from one surface, traverses the substrate, and exits from an opposite surface of the substrate. The opposite surface is populated with micromirrors. By folding the light beams in a switch architecture with the substrate, the size of the switch package is reduced. Using the substrate in combination with a modular approach to substrate population allows for a single die switch with a higher die yield and scalability. Integrated circuits may be placed on the same substrate as the micromirrors, and the complexity of the assembly process is reduced. With the addition of the second cap, the light beam is folded during the switching operation, resulting in a smaller switch package.

Claims

1. A fiber optic cross connect (OXC), comprising:

a substrate, where light beams travel through the substrate;

a plurality of optical fibers optically coupled to a first surface of the substrate; and

a micromirror array optically coupled to a second surface of the substrate.

2. The OXC of claim 1, wherein the second surface of the substrate is parallel to the first surface of the substrate.

3. The OXC of claim 1, wherein the substrate comprises a slab transparent to wavelengths of interest.

4. The OXC of claim 1, wherein the substrate comprises holes through which the light beams may travel.

5. The OXC of claim 1, wherein the substrate comprises a double-sided polished wafer.

6. The OXC of claim 1, wherein the substrate comprises:

a first anti-reflective coating on the first surface of the substrate; and

a second anti-reflective coating on the second surface of the substrate.

7. The OXC of claim 1, wherein the substrate comprises:

integrated circuits on the first or second surfaces of the substrate; and

conductive traces on the first or second surfaces of the substrate.

8. The OXC of claim 7, wherein the integrated circuits are in close proximity to the micromirror array.

9. The OXC of claim 7, wherein the integrated circuits and conductive traces are absent from paths of the light beams traveling through the substrate.

10. The OXC of claim 1, wherein the plurality of optical fibers further comprises:

a housing, wherein the plurality of optical fibers are contained within the housing; and

a plurality of collimators within the housing wherein the plurality of collimators is optically coupled to the plurality of optical fibers.

11. The OXC of claim 1, wherein the micromirror array comprises a plurality of static mirrors.

12. The OXC of claim 1, wherein the micromirror array comprises a plurality of active mirrors.

13. The OXC of claim 1, wherein the micromirror array comprises a plurality of strips, wherein each of the plurality of strips comprises a plurality of micromirrors of the micromirror array.

14. The OXC of claim 1, wherein the micromirror array comprises a plurality of input micromirrors and a plurality of output micromirrors.

15. The OXC of claim 1, wherein the micromirror array is two dimensional.

16. The OXC of claim 1, wherein the micromirror array is coupled to the second surface of the substrate.

17. The OXC of claim 1, further comprising:

a first cap optically coupled to the micromirror array, wherein the first cap is approximately parallel to the first and second surfaces of the substrate;

a first set of sidewalls coupled to the first cap and the second surface of the substrate;

a second cap optically coupled to the first cap, wherein the second cap folds the light beams during a switching operation, wherein the second cap is approximately parallel to the first cap; and

a second set of sidewalls coupled to the second cap and the second surface of the substrate.

18. The OXC of claim 17, wherein the micromirror array is coupled to the first cap.

19. The OXC of claim 17, wherein the first cap further comprises:

a plurality of reflecting surfaces on a first surface or a second surface of the first cap.

20. The OXC of claim 19, wherein the plurality of reflecting surfaces reflects the light beams from a plurality of collimators to the micromirror array and from the micromirror array to the plurality of collimators.

21. The OXC of claim 20, wherein a distance traveled by the light beams between the plurality of collimators and the micromirror array is approximately uniform for each micromirror in the micromirror array.

22. The OXC of claim 17, further comprising:

a plurality of photodetectors residing on a second surface or a first surface of the first cap, wherein the first surface of the first cap is approximately parallel to the second surface of the first cap.

23. The OXC of claim 19, wherein the plurality of reflecting surfaces comprises a plurality of flat mirrors.

24. The OXC of claim 19, wherein the plurality of reflecting surfaces comprises a plurality of curved mirrors.

25. The OXC of claim 19, wherein the plurality of reflecting surfaces comprise active or passive components.

26. The OXC of claim 17, further comprising a third cap optically coupled to the second cap, wherein a distance between the third cap and the second cap is approximately equal to a distance between the micromirror array and the second cap;

and

a third set of sidewalls coupled to the third cap and the second cap.

27. The OXC of claim 26, further comprising a plurality of photodetectors residing on the third cap.

28. The OXC of claim 1, further comprising a plurality of photodetectors residing on the substrate at a location where the light beams travel in or out of the substrate.

29. A method for performing an optical switching operation, comprising the steps of:

(a) directing a light beam into an input port of an OXC;

(b) traversing the light beam through a substrate from a first side of the substrate;

(c) reflecting the light beam utilizing a micromirror array coupled to a second side of the substrate; and

(d) directing the light beam through the substrate from the second side of the substrate to an output port.

30. A system, comprising:

a fiber optic transmission system; and

an OXC optically coupled to the fiber optic transmission system, the OXC comprising;

a substrate, wherein light beams travel through the substrate to or from the fiber optic transmission system,

a plurality of optical fibers optically coupled to a first surface of the substrate; and

a micromirror array optically coupled to a second surface of the substrate.

31. A system, comprising:

an OXC; and

a light beam traversing through the OXC, wherein the light beam is directed into an input port of the OXC, traversed through a substrate of the OXC from a first side of the substrate, reflected to a second side of the substrate by a micromirror array, and directing through the substrate from the second side of the substrate to an output port of the OXC.