Granted Patent B2

US 8,081,875 · App. 12/028,031 · Granted Dec 20, 2011

Abstract

Claims (93)

1. A wavelength switch comprising:

an input port for launching an input beam including first and second groups of sub-beams, wherein each sub-beam of the first and second groups of sub-beams is at a different wavelength band;

first and second groups of output ports for outputting the first and second groups of sub-beams, respectively;

a lensing element with optical power, disposed to receive the input beam from the input port, for redirecting the input beam and the first and second groups of sub-beams;

a wavelength-dispersing element, disposed to receive the input beam from the lensing element, for dispersing the input beam into the first and second groups of sub-beams;

a first switching stage including a first actuation array of reflecting elements, disposed to receive the first and second groups of sub-beams from the wavelength-dispersing element via the lensing element, for routing the first group of sub-beams along a first set of paths and the second group of sub-beams along a second set of paths;

a reflecting relay assembly, disposed to receive the first and second groups of sub-beams from the first switching stage via the lensing element, for redirecting the first group of sub-beams along the first set of paths and the second group of sub-beams along the second set of paths; and

a second switching stage including: a second actuation array of reflecting elements, disposed to receive only the first group of sub-beams from the reflecting relay assembly, for routing each sub-beam of the first group of sub-beams to a selected output port of the first group of output ports; and a third actuation array of reflecting elements, disposed to receive only the second group of sub-beams from the reflecting relay assembly, for routing each sub-beam of the second group of sub-beams to a selected output port of the second group of output ports;

wherein the wavelength-dispersing element is also disposed to receive the first and second groups of sub-beams from the second switching stage via the lensing element, whereby the wavelength-dispersing element combines those sub-beams of the first group of sub-beams that are routed to a same output port of the first group of output ports and those sub-beams of the second group of sub-beams that are routed to a same output port of the second group of output ports;

wherein the first group of output ports is disposed to receive only the first group of sub-beams from the wavelength-dispersing element via the lensing element; and

wherein the second group of output ports is disposed to receive only the second group of sub-beams from the wavelength-dispersing element via the lensing element.

2. The wavelength switch of claim 1 wherein the reflecting relay assembly includes:

a first reflecting stage, disposed to receive the first and second groups of sub-beams from the first actuation array of reflecting elements via the lensing element, for redirecting the first and second groups of sub-beams;

a second reflecting stage, disposed to receive the first and second groups of sub-beams from the first reflecting stage via the lensing element, for redirecting the first and second groups of sub-beams; and

a third reflecting stage, disposed to receive the first and second groups of sub-beams from the second reflecting stage via the lensing element, for redirecting the first group of sub-beams to the second actuation array of reflecting elements and the second group of sub-beams to the third actuation array of reflecting elements.

3. The wavelength switch of claim 2 wherein the first reflecting stage includes: a first planar mirror, disposed to receive only the first group of sub-beams from the first actuation array of reflecting elements via the lensing element, for redirecting the first group of sub-beams; and a second planar mirror, disposed non-parallel to the first planar mirror to receive only the second group of sub-beams from the first actuation array of reflecting elements via the lensing element, for redirecting the second group of sub-beams;

wherein the second reflecting stage includes: a third planar mirror, disposed to receive only the first group of sub-beams from the first planar mirror via the lensing element, for redirecting the first group of sub-beams; and a fourth planar mirror, disposed non-parallel to the third planar mirror to receive only the second group of sub-beams from the second planar mirror via the lensing element, for redirecting the second group of sub-beams; and

wherein the third reflecting stage includes a fifth planar mirror, disposed to receive the first group of sub-beams from the third planar mirror via the lensing element and the second group of sub-beams from the fourth planar mirror via the lensing element, for redirecting the first group of sub-beams to the second actuation array of reflecting elements and the second group of sub-beams to the third actuation array of reflecting elements.

4. The wavelength switch of claim 3 wherein the first and second planar mirrors are separated by a distance of at least three times a waist radius of the first and second groups of sub-beams to allow hitless switching.

5. The wavelength switch of claim 2 wherein the first reflecting stage includes a first planar mirror, disposed to receive the first and second groups of sub-beams from the first actuation array of reflecting elements via the lensing element, for redirecting the first and second groups of sub-beams;

wherein the second reflecting stage includes a reflecting angle-to-offset (ATO) assembly, disposed to receive the first and second groups of sub-beams from the first planar mirror via the lensing element, for converting angular offsets of the first and second groups of sub-beams into positional offsets and for redirecting the first and second groups of sub-beams; and

wherein the third reflecting stage includes a second planar mirror, disposed to receive the first and second groups of sub-beams from the reflecting ATO assembly via the lensing element, for redirecting the first group of sub-beams to the second actuation array of reflecting elements and the second group of sub-beams to the third actuation array of reflecting elements.

6. The wavelength switch of claim 5 wherein the reflecting ATO assembly includes:

a first ATO lens with negative optical power, disposed to receive the first and second groups of sub-beams from the first planar mirror via the lensing element, for redirecting the first and second groups of sub-beams; and

an ATO mirror, disposed to receive the first and second groups of sub-beams from the first ATO lens, for redirecting the first and second groups of sub-beams back to the first ATO lens.

7. The wavelength switch of claim 6 wherein the ATO mirror has positive optical power;

wherein the optical power of the first ATO lens is twice as large in magnitude as the optical power of the ATO mirror; and

wherein the first ATO lens and the ATO mirror are separated by a distance substantially equivalent to the negative of a focal length of the first ATO lens.

8. The wavelength switch of claim 6 wherein the ATO mirror is planar; and

wherein the first ATO lens and the ATO mirror are separated by a distance substantially equivalent to a focal length of the first ATO lens divided by −√{square root over (2)}.

9. The wavelength switch of claim 6 wherein the reflecting ATO assembly further includes a beam-reducing assembly, disposed to receive the first and second groups of sub-beams from the first planar mirror, for reducing the first and second groups of sub-beams in waist size and for redirecting the first and second groups of sub-beams to the first ATO lens.

10. The wavelength switch of claim 9 wherein the beam-reducing assembly includes a second ATO lens with positive optical power, disposed to receive the first and second groups of sub-beams from the first planar mirror, for redirecting the first and second groups of sub-beams.

11. The wavelength switch of claim 10 wherein the beam-reducing assembly further includes a third ATO lens with positive optical power, disposed to receive the first and second groups of sub-beams from the second ATO lens, for redirecting the first and second groups of sub-beams to the first ATO lens;

wherein a ratio of a separation between the second ATO lens and the ATO mirror and a separation between the third ATO lens and the ATO mirror is substantially equivalent to a ratio of a focal length of the second ATO lens to a focal length of the third ATO lens; and

wherein the second and third ATO lenses are separated by a distance substantially equivalent to a sum of the focal length of the second ATO lens and the focal length of the third ATO lens.

12. The wavelength switch of claim 1 wherein the lensing element includes a spherical mirror with positive optical power.

13. The wavelength switch of claim 1 wherein the wavelength-dispersing element includes a reflecting diffraction grating.

14. The wavelength switch of claim 1 wherein the wavelength-dispersing element includes: a transmitting diffraction grating, disposed to receive the input beam from the lensing element, for dispersing the input beam into the first and second groups of sub-beams; and a mirror, disposed to receive the first and second groups of sub-beams from the transmitting diffraction grating, for redirecting the first and second groups of sub-beams back to the transmitting diffraction grating.

15. The wavelength switch of claim 1 further comprising a front-end unit, wherein the input port and the first and second groups of output ports are disposed in the front-end unit.

16. The wavelength switch of claim 1 further comprising a back-end unit, wherein the first, second, and third actuation arrays of reflecting elements are disposed in the back-end unit.

17. The wavelength switch of claim 1 wherein the first, second, and third actuation arrays of reflecting elements are disposed on a single substrate.

18. The wavelength switch of claim 17 wherein the second and third actuation arrays of reflecting elements share common control lines.

19. The wavelength switch of claim 1 wherein the first, second, and third actuation arrays of reflecting elements include microelectromechanical system (MEMS) mirror arrays.

20. The wavelength switch of claim 1 wherein the first, second, and third actuation arrays of reflecting elements include liquid crystal on silicon (LCOS) arrays.

21. The wavelength switch of claim 1 wherein the second and third actuation arrays of reflecting elements are separated by a distance of at least three times a waist radius of the first and second groups of sub-beams to allow hitless switching.

22. The wavelength switch of claim 1 further including:

an input switching lens with positive optical power, disposed to receive the input beam from the input port, for collimating the input beam;

a first output switching lens with positive optical power, disposed to receive only the first group of sub-beams from the wavelength-dispersing element via the lensing element, for converting angular offsets of the first group of sub-beams into positional offsets and for redirecting each sub-beam of the first group of sub-beams to the selected output port of the first group of output ports; and

a second output switching lens with positive optical power, disposed to receive only the second group of sub-beams from the wavelength-dispersing element via the lensing element, for converting angular offsets of the second group of sub-beams into positional offsets and for redirecting each sub-beam of the second group of sub-beams to the selected output port of the second group of output ports.

23. A wavelength-switching method comprising:

launching an input beam including first and second groups of sub-beams from an input port towards a lensing element with optical power, wherein each sub-beam of the first and second groups of sub-beams is at a different wavelength band;

redirecting the input beam from the lensing element to a wavelength-dispersing element;

dispersing the input beam into the first and second groups of sub-beams;

redirecting the first and second groups of sub-beams from the wavelength-dispersing element to a first actuation array of reflecting elements of a first switching stage via the lensing element;

routing the first group of sub-beams along a first set of paths to a second actuation array of reflecting elements of a second switching stage;

routing the second group of sub-beams along a second set of paths to a third actuation array of reflecting elements of the second switching stage;

redirecting the first and second groups of sub-beams from the first switching stage to a reflecting relay assembly via the lensing element;

redirecting only the first group of sub-beams along the first set of paths from the reflecting relay assembly to the second actuation array of reflecting elements of the second switching stage via the lensing element;

redirecting only the second group of sub-beams along the second set of paths from the reflecting relay assembly to the third actuation array of reflecting elements of the second switching stage via the lensing element;

routing each sub-beam of the first group of sub-beams to a selected output port of a first group of output ports;

routing each sub-beam of the second group of sub-beams to a selected output port of a second group of output ports;

redirecting the first and second groups of sub-beams from the second switching stage to the wavelength-dispersing element via the lensing element;

combining those sub-beams of the first group of sub-beams that are routed to a same output port of the first group of output ports;

combining those sub-beams of the second group of sub-beams that are routed to a same output port of the second group of output ports;

redirecting only the first group of sub-beams from the wavelength-dispersing element to the first group of output ports via the lensing element;

redirecting only the second group of sub-beams from the wavelength-dispersing element to the second group of output ports via the lensing element; and

outputting the first and second groups of sub-beams from the first and second groups of output ports, respectively.

24. A wavelength switch comprising:

first and second groups of input ports for launching first and second groups of sub-beams, respectively, wherein each sub-beam of the first and second groups of sub-beams is at a different wavelength band;

an output port for outputting an output beam including the first and second groups of sub-beams;

a lensing element with optical power, disposed to receive only the first group of sub-beams from the first group of input ports and only the second group of sub-beams from the second group of input ports, for redirecting the first and second groups of sub-beams and the output beam;

a wavelength-dispersing element, disposed to receive the first and second groups of sub-beams from the lensing element, for dispersing those sub-beams of the first group of sub-beams that are received from a same input port of the first group of input ports via the lensing element and those sub-beams of the second group of sub-beams that are received from a same input port of the second group of input ports via the lensing element;

a first switching stage including: a first actuation array of reflecting elements, disposed to receive only the first group of sub-beams from the wavelength-dispersing element via the lensing element, for routing the first group of sub-beams along a first set of paths; and a second actuation array of reflecting elements, disposed to receive only the second group of sub-beams from the wavelength-dispersing element via the lensing element, for routing the second group of sub-beams along a second set of paths;

a reflecting relay assembly, disposed to receive the first and second groups of sub-beams from the first switching stage via the lensing element, for redirecting the first group of sub-beams along the first set of paths and the second group of sub-beams along the second set of paths; and

a second switching stage including a third actuation array of reflecting elements, disposed to receive the first and second groups of sub-beams from the reflecting relay assembly, for routing each sub-beam of the first and second groups of sub-beams to the output port;

wherein the wavelength-dispersing element is also disposed to receive the first and second groups of sub-beams from the second switching stage via the lensing element, whereby the wavelength-dispersing element combines the first and second groups of sub-beams into the output beam; and

wherein the output port is disposed to receive the output beam from the wavelength-dispersing element via the lensing element.

25. A wavelength-switching method comprising:

launching first and second groups of sub-beams from first and second groups of input ports, respectively, towards a lensing element with optical power, wherein each sub-beam of the first and second groups of sub-beams is at a different wavelength band;

redirecting the first and second groups of sub-beams from the lensing element to a wavelength-dispersing element;

dispersing those sub-beams of the first group of sub-beams that are received from a same input port of the first group of input ports via the lensing element and those sub-beams of the second group of sub-beams that are received from a same input port of the second group of input ports via the lensing element;

redirecting only the first group of sub-beams from the wavelength-dispersing element to a first actuation array of reflecting elements of a first switching stage via the lensing element;

redirecting only the second group of sub-beams from the wavelength-dispersing element to a second actuation array of reflecting elements of the first switching stage via the lensing element;

routing the first group of sub-beams along a first set of paths to a third actuation array of reflecting elements of a second switching stage;

routing the second group of sub-beams along a second set of paths to the third actuation array of reflecting elements of the second switching stage;

redirecting the first and second groups of sub-beams from the first switching stage to a reflecting relay assembly via the lensing element;

redirecting only the first group of sub-beams along the first set of paths from the reflecting relay assembly to the third actuation array of reflecting elements of the second switching stage via the lensing element;

redirecting only the second group of sub-beams along the second set of paths from the reflecting relay assembly to the third actuation array of reflecting elements of the second switching stage via the lensing element;

routing each sub-beam of the first and second groups of sub-beams to a same output port;

redirecting the first and second groups of sub-beams from the second switching stage to the wavelength-dispersing element via the lensing element;

combining the first and second groups of sub-beams into an output beam;

redirecting the output beam from the wavelength-dispersing element to the output port via the lensing element; and

outputting the output beam from the output port.

Assignments (6)