Switchable wavelength router

Claim 2

An switchable wavelength router selectively directing predetermined spectral bands in an input beam to a plurality of output ports determined by a specified control state, said router comprising: an input port receiving an input beam; a first polarization-dependent routing element separating said input beam into a pair of orthogonally-polarized beams; and a network of wavelength routing switches receiving said pair of beams exiting said first polarization-dependent routing element and having a plurality of output ports, wherein said wavelength routing switches include: (a) a polarization rotator for selectively rotating the polarization of at least one of a pair of input beams to create first and second beams having the same polarization determined by said control state; (b) a wavelength filter coupled to receive said first and second beams from said polarization rotator, said wavelength filter having a polarization dependent optical transmission function such that the said first beam decomposes into third and fourth beams with their polarizations orthogonal to each other, and said second beam decomposes into fifth and sixth beams with their polarizations orthogonal to each other, wherein said third and fifth beams carry a first predetermined spectral band at a first polarization and said fourth and sixth beams carry a second predetermined spectral band at a second polarization, wherein said first and second spectral bands are substantially complementary and said first and second polarizations are orthogonal; and (c) a polarization-dependent routing element spatially routing said third and fifth beams along a first optical path and said fourth and sixth beams along a second optical path based on their polarizations; wherein said output ports receive a pair of output beams from said network of wavelength routing switches and include: (a) a polarization rotator for rotating the polarization of at least one of said output beams so that said output beams are orthogonally polarized; and (b) a polarization-dependent routing element combining said orthogonally-polarized output beams at said output port.

Claim 3

The router of claim 1 wherein said wavelength filter comprises a stacked plurality of birefringent waveplates with each waveplate oriented in a predetermined direction.

Claim 4

The router of claim 1 wherein said polarization-dependent routing elements comprise a polarized beamsplitter.

Claim 5

The router of claim 1 wherein said polarization-dependent routing elements comprise an angled polarization separator.

Claim 6

The router of claim 1 wherein said polarization-dependent routing elements comprise a birefringent element.

Claim 7

The router of claim 1 wherein said network of wavelength routing switches comprises 1×2 wavelength routing switches.

Claim 8

The router of claim 1 wherein said network of wavelength routing switches comprises a binary tree structure.

Claim 9

The router of claim 1 wherein said polarization rotator means comprise a liquid crystal polarization rotator.

Claim 10

The router of claim 8 wherein said liquid crystal polarization rotator has a plurality of pixels.

Claim 11

A switchable wavelength router comprising: a first polarization-dependent routing element for receiving an WDM optical signal and decomposing said WDM optical signal into a first beam and a second beam that have orthogonal polarizations and are spatially separated; a first polarization rotator having a first control state in which the polarization of said first beam is rotated to substantially match the polarization of said second beam, and a second control state in which the polarization of said second beam is rotated to substantially match the polarization of said first beam; the control state of said first polarization rotator being switchable by an external control signal; a wavelength filter coupled to receive said first and second beams from said first polarization rotator, said wavelength filter having a polarization dependent optical transmission function such that the said first beam decomposes into third and fourth beams with their polarizations orthogonal to each other, and said second beam decomposes into fifth and sixth beams with their polarizations orthogonal to each other, wherein said third and fifth beams carry a first predetermined spectral band at a first polarization and said fourth and sixth beams carry a second predetermined spectral band at a second polarization, wherein said first and second spectral bands are substantially complementary and said first and second polarizations are orthogonal; a second polarization-dependent routing element for spatially separating said third, fourth, fifth, and sixth beams into four horizontally polarized and vertically polarized components; a second polarization rotator for rotating the polarizations of said third, fourth, fifth, and sixth beams such that said third and fifth beams are orthogonally polarized and said fourth and sixth beams are orthogonally polarized; and a third polarization-dependent routing element for receiving said third, fourth, fifth, and sixth beams from said second polarization rotator, spatially recombining said third and fifth beams containing said first spectral band, and spatially recombining said fourth and sixth beams containing said second spectral band.

Claim 12

A switchable wavelength router comprising: a first polarization-dependent routing element for receiving an WDM optical signal and decomposing said WDM optical signal into a first beam and a second beam that have orthogonal polarizations and are spatially separated; a first polarization rotator having a first control state in which the polarization of said first beam is rotated to substantially match the polarization of said second beam, and a second control state in which the polarization of said second beam is rotated to substantially match the polarization of said first beam; the control state of said first polarization rotator being switchable by an external control signal; a wavelength filter coupled to receive said first and second beams from said first polarization rotator, said wavelength filter having a polarization dependent optical transmission function such that the said first beam decomposes into third and fourth beams with their polarizations orthogonal to each other, and said second beam decomposes into fifth and sixth beams with their polarizations orthogonal to each other, wherein said third and fifth beams carry a first predetermined spectral band at a first polarization and said fourth and sixth beams carry a second predetermined spectral band at a second polarization, wherein said first and second spectral bands are substantially complementary and said first and second polarizations are orthogonal; a second polarization-dependent routing element for spatially separating said third, fourth, fifth, and sixth beams into four horizontally polarized and vertically polarized components; a second polarization rotator for rotating the polarizations of said third, fourth, fifth, and sixth beams such that said third and fifth beams are orthogonally polarized and said fourth and sixth beams are orthogonally polarized; and a third polarization-dependent routing element for receiving said third, fourth, fifth, and sixth beams from said second polarization rotator, spatially recombining said third and fifth beams containing said first spectral band, and spatially recombining said fourth and sixth beams containing said second spectral band.

Claim 13

The router of claim 10 wherein said first polarization rotator further comprises: a first area for rotating the polarization of said first beam in said first control state, and passing said first beam without rotation in said second control state; and a second area for passing said second beam without rotation in said first control state, and rotating the polarization of said second beam in said second control state.

Claim 14

The router of claim 10 wherein said second polarization rotator further comprises: (a) a first area for rotating the polarization of said fifth beam; (b) a second area for rotating the polarization of said sixth beam; (c) a third are for passing said third beam without rotation; and (b) a fourth area for passing said fourth beam without rotation.

Claim 15

The router of claim 10 wherein said wavelength filter comprises a stacked plurality of birefringent waveplates with each waveplate oriented in a predetermined direction.

Claim 16

The router of claim 10 wherein said polarization-dependent routing element comprises a birefringent element.

Claim 17

The router of claim 10 wherein said polarization-dependent routing element comprises a polarized beamsplitter.

Claim 18

The router of claim 10 wherein said polarization-dependent routing element comprises an angled polarized separator.