Wavelength-selective switch and integrated wavelength demultiplexer using stacked planar lightwave circuits

• US 7,257,285 B2
• Filed: 03/04/2005
• Issued: 08/14/2007
• Est. Priority Date: 03/04/2005
• Status: Active Grant

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Doerr, Christopher Richard, Marom, Dan Mark
• Primary Examiner(s): Font; Frank G.
• Assistant Examiner(s): Mooney; Michael P.
• Application Number:
  US11/073,010
• Publication Number:
  US 20060198575A1
• Time in Patent Office: 893 Days
• Field of Search: 385/16, 385/18, 385/24, 385/27, 385/33, 385/37, 385/46, 385/129, 385/14
• US Class Current: 385/18
• 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 6/12026 characterised by means for reducing the temperature dependence
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• 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: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0016 using wavelength multiplexing or demultiplexing
• CPC Class Codes: H04Q 2011/0026 using free space propagation (e.g. lenses, mirrors)
• CPC Class Codes: H04Q 2011/0032 using static wavelength routers (e.g. arrayed waveguide grating router [AWGR] )

Abstract

Wavelength-selective switches (WSSs) having embedded multiplexer or demultiplexer functionality include a stack of planar waveguide circuits (PLCs) in which all but one of the PLCs have identical features consisting of a single waveguide connected to a free space region, further connected to a waveguide array that terminates at the PLC edge facet, which are placed at the front focal plane of a lens, generating a spectrally resolved optical signal at the back focal plane of the lens. Due to the use of a single lens, the spectrally resolved optical signal of all the PLCs are superimposed, differing only by propagation direction. A tilting micro-mirror array at the back focal plane reflects the spectral components, implementing a wavelength-selective switch. The reflected light can couple to any of the remaining PLCs, for multiplexing, or to the different PLC in the stack, which implements the multiplexer/demultiplexer.

Claims

1. A wavelength-selective switch, comprising:

a lens;

a micro-mirror array; and

a plurality of stacked planar lightwave circuits, each further comprising a waveguide grating and a facet facing the lens and micro-mirror array;

wherein a first planar waveguide circuit of the plurality of planar waveguide circuits comprises a first edge facet;

a first arrayed waveguide grating coupled to the first edge facet;

a first free space region coupled to the first arrayed waveguide grating;

a single waveguide coupled to the first free space region;

a second free space region coupled to the single waveguide;

a second arrayed waveguide grating coupled to the second free space region;

a third free space region coupled to the second arrayed waveguide grating; and

a plurality of individual waveguides each coupled to the third free space region.

2. The wavelength-selective switch of claim 1, wherein the micro-mirror array is a tilting micro-mirror array positioned at the back focal plane of the lens.

3. The wavelength-selective switch of claim 1, wherein the planar waveguide circuits of the plurality of planar waveguide circuits, other than the first planar waveguide circuit, are substantially identical.

4. The wavelength-selective switch of claim 1, wherein the first planar waveguide circuit is operable to provide predetermined passband characteristics.

5. The wavelength-selective switch of claim 1, wherein the first arrayed waveguide grating is operable to undo angular dispersion;

and wherein the plurality of individual waveguides are adapted for coupling to a fiber array.

6. The wavelength-selective switch of claim 1, wherein the first arrayed waveguide grating and the second arrayed waveguide grating have different characteristics.

7. The wavelength-selective switch of claim 6, wherein the first arrayed waveguide grating provides a first resolution such that a wavelength division multiplexed channel is well confined on an individual micro-mirror of the micro-mirror array.

8. The wavelength-selective switch of claim 6, wherein the second arrayed waveguide grating provides a second resolution such that a wavelength division multiplexed channel exhibits predetermined passband characteristics when coupled to the output fiber.

9. The wavelength-selective switch of claim 1, wherein the at least one input port is coupled to the planar waveguide circuit that is disposed on the top of the stack.

10. An optical network node, comprising:

a first wavelength-selective switch, having at least one input port adapted to couple to at least one ingress fiber, the first wavelength-selective switch having a plurality of drop ports, and at least one output port; and

a second wavelength-selective switch, having at least one input port coupled to the at least one output port of the first wavelength-selective switch, the second wavelength-selective switch having a plurality of add ports, and at least one output port;

wherein the first wavelength-selective switch includes a stack of planar lightwave circuits having the plurality of add ports integrated therein, and the second wavelength-selective switch includes a stack of planar lightwave circuits having the plurality of drop ports integrated therein.

11. The optical network node of claim 10, wherein the stack of planar lightwave circuits of the first wavelength-selective switch comprises:

a plurality of stacked, substantially identical, first planar waveguide circuits, each comprising a single waveguide connected to a free space region, and further connected to an arrayed waveguide grating that terminates at a planar waveguide circuit edge facet;

a second planar waveguide circuit, different from the first planar waveguide circuits, stacked with the plurality of first planar waveguide circuits; and

a lens, positioned such that the planar waveguide circuit edge facets are at a front focal plane of the lens, operable to generate a spectrally resolved optical signal at a back focal plane of the lens, thereby implementing a spatial Fourier transform;

wherein the wavelength-selective switch has at least one input port and at least one output port.

12. The optical network node of claim 11, wherein the first wavelength-selective switch further comprises a tilting micro-mirror array positioned at the back focal plane of the lens, operable to reflect the spectral components.

13. The optical network node of claim 12, wherein the second planar waveguide of the first wavelength-selective switch comprises:

a first edge facet;

a first arrayed waveguide grating coupled to the first edge facet;

a first free space region coupled to the first arrayed waveguide grating;

a single waveguide coupled to the first free space regions;

a second free space region coupled to the single waveguide;

a second arrayed waveguide grating coupled to the second free space region;

a third free space region coupled to the second arrayed waveguide grating; and

a plurality of individual waveguides each coupled to the third free space region;

wherein the first arrayed waveguide grating is operable to undo angular dispersion; and

wherein the plurality of individual waveguides are adapted for coupling to a fiber array.

14. The optical network node of claim 10, wherein the first wavelength-selective switch and the second wavelength-selective switch are the same.

15. The optical network node of claim 12, wherein the second planar waveguide of the first wavelength-selective switch comprises:

a first edge facet;

a first arrayed waveguide grating coupled to the first edge facet;

a free space region coupled to the first arrayed waveguide grating; and

a plurality of individual waveguides each coupled to the free space region;

wherein the first arrayed waveguide grating has a grating order which is less than a grating order of the arrayed waveguide grating of the first planar waveguide circuit.

16. The optical network node of claim 15, wherein the grating order of the first arrayed waveguide grating is one-half the grating order of the arrayed waveguide grating of the first planar waveguide circuit.

17. The optical network node of claim 10, wherein a plurality of substantially identical, first planar waveguide circuits, each comprising at least one waveguide connected to a free space region, and further connected to an arrayed waveguide grating that terminates at a planar waveguide circuit edge facet;

and a second planar waveguide circuit, different from the first planar waveguide circuits, horizontally adjacent with the plurality of first planar waveguide circuits.

18. A method of producing a wavelength-selective switch, comprising:

stacking a plurality of substantially identical first planar waveguide circuits, the first planar waveguide circuits having edge facets;

stacking a second planar waveguide circuit, the second planar waveguide circuit different from the first planar waveguide circuits, with the plurality of first planar waveguide circuits, the second planar waveguide circuit having an edge facet;

positioning a lens such that the first and second planar waveguide circuit edge facets are at a front focal plane of the lens, and the lens is operable to generate a spectrally resolved optical signal at a back focal plane of the lens;

positioning a tilting micro-mirror array at the back focal plane of the lens, such that the tilting micro-mirror array is operable to reflect the spectral components; and

coupling a fiber array to the second planar waveguide circuit.

19. The method of claim 18, wherein the second planar waveguide circuit comprises:

a first edge facet;

a first arrayed waveguide grating coupled to the first edge facet;

a first free space region coupled to the first arrayed waveguide grating;

a single waveguide coupled to the first free space regions;

a second free space region coupled to the single waveguide;

a second arrayed waveguide grating coupled to the second free space region;

a third free space region coupled to the second arrayed waveguide grating; and

a plurality of individual waveguides each coupled to the third free space region;

wherein the first arrayed waveguide grating is operable to undo angular dispersion; and

wherein the plurality of individual waveguides are adapted for coupling to a fiber array.

20. The method of claim 18, wherein the second planar waveguide circuit comprises:

a first edge facet;

a first arrayed waveguide grating coupled to the first edge facet;

a free space region coupled to the first arrayed waveguide grating; and

a plurality of individual waveguides each coupled to the free space region;

wherein the first arrayed waveguide grating has a grating order which is less than a grating order of the arrayed waveguide grating of the first planar waveguide circuit.