Wavelength selective switch

• US 7,027,684 B2
• Filed: 05/20/2003
• Issued: 04/11/2006
• Est. Priority Date: 05/20/2002
• Status: Expired due to Term

• Current Assignee: Lumentum Operations, LLC (Lumentum Holdings Inc.)
• Original Assignee: Metconnex Canada Inc.
• Inventors: Ducellier, Thomas, Hnatiw, Alan
• Primary Examiner(s): Healy, Brian
• Assistant Examiner(s): BLEVINS, JERRY M
• Application Number:
  US10/493,102
• Publication Number:
  US 20040258351A1
• Time in Patent Office: 1,057 Days
• Field of Search: 385/24, 385/15, 385/16, 385/17, 385/18, 398/79, 398/81, 398/80, 398/82, 398/83, 398/84, 398/85
• US Class Current: 385/24
• CPC Class Codes: G02B 6/12011 characterised by the arrayed waveguides, e.g. comprising a filled groove in the array section
• CPC Class Codes: G02B 6/12021 Comprising cascaded AWG devices; AWG multipass configuration; Plural AWG devices integrated on a single chip
• CPC Class Codes: G02B 6/12033 characterised by means for configuring the device, e.g. moveable element for wavelength tuning switching G02B6/35; thermo-optic devices G02F1/0147
• CPC Class Codes: G02B 6/2931 Diffractive element operating in reflection
• CPC Class Codes: G02B 6/29311 Diffractive element operating in transmission
• CPC Class Codes: G02B 6/29313 characterised by means for controlling the position or direction of light incident to or leaving the diffractive element, e.g. for varying the wavelength response switching G02B6/35
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0022 using fibre gratings
• CPC Class Codes: H04Q 2011/0026 using free space propagation (e.g. lenses, mirrors)
• CPC Class Codes: H04Q 2011/003 using switches based on microelectro-mechanical systems [MEMS]
• CPC Class Codes: H04Q 2011/0032 using static wavelength routers (e.g. arrayed waveguide grating router [AWGR] )
• CPC Class Codes: H04Q 2011/0049 Crosstalk reduction; Noise; Power budget

Abstract

A wavelength selective switch is realized by combining a quantized dispersion element and an array of switching means. The quantized dispersion element enables to concentrate all the wavelengths within predetermined wavelength bands onto the same location in the switching array. With this arrangement, a low fill factor switching array can be used while maintaining good flat-top spectral performance with no spectral dips and improving alignment tolerances.

Claims

1. A wavelength switch comprising:

at least one quantized dispersive element having a substantially quantized dispersion characteristic adapted to demultiplex an incoming DWDM light beam to produce a plurality of demultiplexed light beams;

a plurality of switching elements each adapted to perform light beam redirection;

the at least one quantized dispersive element being arranged to direct a respective one of the plurality of demultiplexed light beams to a respective single switching element in the plurality of switching elements for redirection;

wherein each quantized dispersive element exhibits a substantially staircase dispersion characteristic whereby the quantized dispersive element disperses each range of a plurality of ranges of wavelengths substantially at a respective angle of a finite set of angles.

2. A switch according to claim 1 further comprising:

a bulk optical element having optical power between the at least one quantized dispersive element and the plurality of switching elements adapted to couple each demultiplexed light beam onto the respective switching element.

3. A switch according to claim 2 wherein the bulk optical element having optical power is selected from a group consisting of a lens, a curved minor, an assembly of lenses and mirrors, and an assembly of lenses, mirrors and curved mirror.

4. A switch according to claim 1 comprising:

a plurality of dispersive elements including said at least one quantized dispersive element;

a respective port for each dispersive element;

wherein the switching elements are adapted to redirect each of the plurality of light beams to a respective one of the dispersive elements.

5. A switch according to claim 4 wherein all of the dispersive elements have a substantially quantized dispersion characteristic.

6. A switch according to claim 2 comprising a plurality of dispersive elements including said at least one quantized dispersive element,

wherein the switching elements are adapted to redirect each of the plurality of light beams through the bulk optical element to a respective one of the dispersive elements.

7. A switch according to claim 6 wherein all of the dispersive elements have a substantially quantized dispersion characteristic.

8. A switch according to claim 1 wherein the array of switching elements comprises an array of tiltable micro-mirrors.

9. A switch according to claim 1 wherein the array of switching elements comprises transmissive switching elements, the switch further comprising:

a plurality of dispersive elements, wherein at least one of the plurality of dispersive elements has a substantially quantized dispersion characteristic; and

a respective port for said at least one quantized dispersive element and for each of the plurality of dispersive elements;

wherein the transmissive switching elements are adapted to redirect each of the plurality of light beams to a respective one of the plurality of dispersive elements.

10. A switch according to claim 9 wherein all of said plurality of dispersive elements have a substantially quantized dispersion characteristic.

11. A switch according to claim 6 wherein the array of switching elements comprises an array of tiltable micro-mirrors and wherein the dispersive elements and the array of tiltable micro-mirrors are placed substantially at focal planes of the bulk optical element having optical power.

12. A switch according to claim 1 wherein the plurality of switching elements comprises a plurality of beam steering means in transmission.

13. A switch according to claim 6 wherein the plurality of switching elements comprises a plurality of beam steering means in transmission comprising either an optical phase array or an electro-hologram and wherein the dispersive elements and the plurality of beam steering means are placed substantially at focal planes of the bulk optical element having optical power.

14. A switch according to claim 1 further comprising:

a respective port for each dispersive element;

a micro-optics coupling scheme adapted to couple light from each input port to and from the respective dispersive element.

15. A switch according to claim 1 further comprising:

a respective port for each dispersive element;

an integrated coupling optics scheme adapted to couple light from each port to and from the respective dispersive element.

16. A switch according to claim 1 wherein each quantized dispersive element is fabricated on a waveguide substrate.

17. A switch according to claim 16 wherein the bulk optical element having power comprises:

a first transverse cylindrical lens adapted to substantially collimate light in a plane perpendicular to a plane of the waveguide substrate;

a main cylindrical lens element adapted to focus light in a second plane in the plane of the waveguide substrate.

18. A switch according to claim 17 wherein the main cylindrical lens has a focal length such that the at least one waveguide dispersive elements are in a focal plane of the lens on a first side of the lens, and the plurality of switching elements are in a focal plane of the lens on a second side of the lens.

19. A switch according to claim 1 wherein each substantially quantized dispersive element comprises:

two continuous dispersive elements providing respective dispersion steps of D/2;

a plurality of micro-telescopes situated between the two continuous dispersive elements adapted to invert wavelengths within respective predetermined bands defined by a physical extent of the micro-telescopes and their spacing.

20. A switch according to claim 19 wherein the two continuous dispersive elements comprise transmissive diffraction gratings.

21. A switch according to claim 19 wherein the two continuous dispersive elements comprise reflective diffraction gratings.

22. A switch according to claim 19 wherein the two continuous dispersive elements comprise prisms.

23. A switch according to claim 16 wherein each substantially quantized dispersive element comprises:

a concatenation of a first arrayed waveguide grating (AWG) and a second AWG with a free spectral range (FSR) of the first AWG equalling a channel spacing of the second AWG.

24. A switch according to claim 16 wherein each substantially quantized dispersive element comprises:

at least two groups of waveguides, each group containing multiple waveguides having a predetermined relative phase relationship, and one of the at least two groups having a larger relative phase offset.

25. A switch according to claim 24 wherein a phase offset between the at least two groups of waveguides corresponds to a channel spacing while the relative phase relationship between the waveguides in each of the at least two groups is chosen to provide a large FSR and the channel spacing.

26. A switch according to claim 1 wherein the array of switching elements is a low fill factor switching array.

27. A switch comprising:

a plurality of ports;

for each port, a respective dispersive element wit a substantially quantized dispersion characteristic;

a plurality of switching elements;

a bulk optical element having optical power adapted to couple a demultiplexed light beam received from any of the dispersive elements to one of the switching elements and to couple each light beam received from one of the switching elements to a respective one of the dispersive elements;

wherein each dispersive element further multiplexes any light beams received from the bulk optical element having power to produce a respective a multiplexed output signal at the respective port;

wherein each quantized dispersive element exhibits a substantially staircase dispersion characteristic whereby the quantized dispersive element disperses each range of a plurality of ranges of wavelengths substantially at a respective angle of a finite set of angles.

28. A method of wavelength switching comprising:

demultiplexing an incoming DWDM light beam using a quantized dispersive element to produce demultiplexed beams;

coupling the demultiplexed beams onto respective switching elements in an array;

remultiplexing the light beams into output ports;

wherein each quantized dispersive element exhibits a substantially staircase dispersion characteristic whereby the quantized dispersive element disperses each range of a plurality of ranges of wavelengths substantially of a respective angle of a finite set of angles.

29. An apparatus comprising:

at least one quantized dispersive element having a substantially quantized dispersion characteristic adapted to demultiplex an incoming DWDM light beam to produce a plurality of demultiplexed light beams;

a plurality of light processing elements each adapted to perform light processing;

the at least one quantized dispersive element being arranged to direct a respective one of the plurality of demultiplexed light beams to a respective single light processing element in the plurality of light processing elements for processing;

wherein each quantized dispersive element exhibits a substantially staircase dispersion characteristic whereby the quantized dispersive element disperses each range of a plurality of ranges of wavelengths substantially at a respective angle of a finite set of angles.

30. The apparatus of claim 29 wherein the light processing element is adapted to perform at least one of changing polarization state, attenuating power, detecting light signals, limiting.

31. A method comprising:

demultiplexing an incoming DWDM light beam using a quantized dispersive element to produce demultiplexed beams;

coupling the demultiplexed beams onto respective light processing elements in an array;

processing the demultiplexed beams with the light processing elements;

wherein each quantized dispersive element exhibits a substantially staircase dispersion characteristic whereby the quantized dispersive element disperses each range of a plurality of ranges of wavelengths substantially at a respective angle of a finite set of angles.