Non-reciprocal optical waveguide coupling device

Claim 2

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and a non-reciprocal element comprising a plurality of optical components, the components cooperating so that light beams from the first optical waveguide couple into the second optical waveguide but light beams from the second optical waveguide do not couple into the first optical waveguide, all of said components being situated adjacent one of the foci, the device further comprising at least one optical waveguide adjacent the first optical waveguide and at least one optical waveguide adjacent the second optical waveguide, the arrangement being such that light beams from the at least one optical waveguide adjacent the first optical waveguide are coupled into the at least one optical waveguide adjacent the second optical waveguide, while light beams from the at least one optical waveguide adjacent the second optical waveguide are displaced away from the at least one optical waveguide adjacent the first optical waveguide.

Claim 3

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and a non-reciprocal element comprising a plurality of optical components, the components cooperating so that light beams from the first optical waveguide couple into the second optical waveguide but light beams from the second optical waveguide do not couple into the first optical waveguide, all of said components being situated adjacent one of the foci, the device further comprising at least one additional optical waveguide, the non-reciprocal element being configured such that light beams from the first optical waveguide are coupled into the second optical waveguide and light beams from the second optical waveguide are coupled into said at least one additional waveguide.

Claim 4

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and a non-reciprocal element comprising a plurality of optical components, the components cooperating so that light beams from the first optical waveguide couple into the second optical waveguide but light beams from the second optical waveguide do not couple into the first optical waveguide, all of said components being situated adjacent one of the foci, the device further comprising at least one additional optical waveguide, the non-reciprocal element being configured such that light beams from the first optical waveguide are coupled into the second optical waveguide and light beams from the second optical waveguide are coupled into said at least one additional waveguide.

Claim 5

A device as claimed in claim 2, wherein the non-reciprocal element is positioned adjacent the first optical waveguide.

Claim 6

A device as claimed in claim 2, wherein the non-reciprocal element is positioned adjacent the second optical waveguide.

Claim 7

A device as claimed in claim 2, wherein the non-reciprocal element comprises, in succession, a first birefringent component for splitting an input light beam travelling in a forward direction into two orthogonally polarized light beam components, a second birefringent component for recombining the light beam components travelling in the forward direction and for splitting a light beam from the second optical waveguide into two orthogonally-polarized light beam components travelling in the reverse direction, and, disposed between the first birefringent component and the second birefringent component, a third birefringent component for displacing the light beam components passing therethrough and polarization-rotation components for rotating respective polarization directions of the light beam components, such that light beams from the first optical waveguide are coupled into the second optical waveguide and light beam components travelling in the reverse direction from the second optical waveguide are displaced away from the first optical waveguide and recombined by the first birefringent component and coupled into said at least one additional waveguide.

Claim 8

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and at least two non-reciprocal elements each situated adjacent one of the foci, between the focusing lens means and an adjacent end of one of the optical waveguides, each of the non-reciprocal elements comprising a plurality of optical components comprising, in succession, a first birefringent component for splitting an input light beam travelling in a forward direction into two orthogonally polarized light beam components, a second birefringent component for recombining the light beam components travelling in the forward direction and for splitting a light beam from the second optical waveguide into two orthogonally-polarized light beam components travelling in the reverse direction, and, disposed between the first birefringent component and the second birefringent component, polarization rotation components for rotating respective polarization directions of the light beam components, the arrangement being such that light beams leaving the first optical waveguide are coupled into the second optical waveguide but light beams leaving the second optical waveguide are displaced away from, and do not couple into, the first optical waveguide.

Claim 9

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and at least two non-reciprocal elements each situated adjacent one of the foci, between the focusing lens means and an adjacent end of one of the optical waveguides, each of the non-reciprocal elements comprising a plurality of optical components comprising, in succession, a first birefringent component for splitting an input light beam travelling in a forward direction into two orthogonally polarized light beam components, a second birefringent component for recombining the light beam components travelling in the forward direction and for splitting a light beam from the second optical waveguide into two orthogonally-polarized light beam components travelling in the reverse direction, and, disposed between the first birefringent component and the second birefringent component, polarization rotation components for rotating respective polarization directions of the light beam components, the arrangement being such that light beams leaving the first optical waveguide are coupled into the second optical waveguide but light beams leaving the second optical waveguide are displaced away from, and do not couple into, the first optical waveguide.

Claim 10

A device as claimed in claim 6, wherein each of the two non-reciprocal elements is positioned adjacent a respective one of the foci of the focusing lens means.

Claim 11

A device as claimed in claim 6, wherein the first and second non-reciprocal elements are so disposed that respective displacement axes of components of one of the elements are angularly displaced about a longitudinal axis of the optical path relative to the displacement axes of corresponding components of the other of the non-reciprocal elements.

Claim 12

A device as claimed in claim 8, wherein the angular displacement is about ninety degrees.

Claim 13

A device as claimed in claim 9, wherein the rod lens means comprises two graded-index rod lenses each of substantially one quarter pitch and an additional optical element is interposed between them.

Claim 14

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and a non-reciprocal element situated adjacent one of the foci, between the focusing lens means and an adjacent end of one of the optical waveguides, the non-reciprocal element comprising a plurality of optical components comprising, in succession, a first birefringent component for splitting an input light beam travelling in a forward direction into two orthogonally polarized light beam components, a second birefringent component for recombining the light beam components travelling in the forward direction and for splitting a light beam from the second optical waveguide into two orthogonally-polarized light beam components travelling in the reverse direction, and, disposed between the first birefringent component and the second birefringent component, polarization rotation components for rotating respective polarization directions of the light beam components, the arrangement being such that light beams leaving the first optical waveguide are coupled into the second optical waveguide but light beams leaving the second optical waveguide are displaced away from, and do not couple into, the first optical waveguide, wherein the focusing lens means comprises at least first and second lens elements and an additional optical element is interposed between said lens elements.

Claim 15

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and a non-reciprocal element situated adjacent one of the foci, between the focusing lens means and an adjacent end of one of the optical waveguides, the non-reciprocal element comprising a plurality of optical components comprising, in succession, a first birefringent component for splitting an input light beam travelling in a forward direction into two orthogonally polarized light beam components, a second birefringent component for recombining the light beam components travelling in the forward direction and for splitting a light beam from the second optical waveguide into two orthogonally-polarized light beam components travelling in the reverse direction, and, disposed between the first birefringent component and the second birefringent component, polarization rotation components for rotating respective polarization directions of the light beam components, the arrangement being such that light beams leaving the first optical waveguide are coupled into the second optical waveguide but light beams leaving the second optical waveguide are displaced away from, and do not couple into, the first optical waveguide, wherein the focusing lens means comprises at least first and second lens elements and an additional optical element is interposed between said lens elements.

Claim 16

A device as claimed in claim 8, wherein the additional optical element comprises a filter interposed between said lens elements.

Claim 17

A device as claimed in claim 8, wherein the additional optical element comprises a partial reflector interposed between said lens elements, the device further comprising an additional optical waveguide for receiving light beams reflected by the partial reflector.

Claim 18

A device as claimed in claim 13, wherein the non-reciprocal element is disposed between the lens means and one of the second optical waveguide and the additional optical waveguide.

Claim 19

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and a non-reciprocal element situated adjacent one of the foci, between the focusing lens means and an adjacent end of one of the optical waveguides, the non-reciprocal element comprising a plurality of optical components comprising, in succession, a first birefringent component for splitting an input light beam travelling in a forward direction into two orthogonally polarized light beam components, a second birefringent component for recombining the light beam components travelling in the forward direction and for splitting a light beam from the second optical waveguide into two orthogonally-polarized light beam components travelling in the reverse direction, and, disposed between the first birefringent component and the second birefringent component, polarization rotation components for rotating respective polarization directions of the light beam components, the arrangement being such that light beams leaving the first optical waveguide are coupled into the second optical waveguide but light beams leaving the second optical waveguide are displaced away from, and do not couple into, the first optical waveguide, wherein the focusing lens means comprises a graded-index rod lens means having a length less than the distance between the foci by about the optical length of the non-reciprocal element and the non-reciprocal element is positioned between one end of the rod lens means and the adjacent waveguide.

Claim 20

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and a non-reciprocal element situated adjacent one of the foci, between the focusing lens means and an adjacent end of one of the optical waveguides, the non-reciprocal element comprising a plurality of optical components comprising, in succession, a first birefringent component for splitting an input light beam travelling in a forward direction into two orthogonally polarized light beam components, a second birefringent component for recombining the light beam components travelling in the forward direction and for splitting a light beam from the second optical waveguide into two orthogonally-polarized light beam components travelling in the reverse direction, and, disposed between the first birefringent component and the second birefringent component, polarization rotation components for rotating respective polarization directions of the light beam components, the arrangement being such that light beams leaving the first optical waveguide are coupled into the second optical waveguide but light beams leaving the second optical waveguide are displaced away from, and do not couple into, the first optical waveguide, wherein the focusing lens means comprises a graded-index rod lens means having a length less than the distance between the foci by about the optical length of the non-reciprocal element and the non-reciprocal element is positioned between one end of the rod lens means and the adjacent waveguide.

Claim 21

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and a non-reciprocal element comprising a plurality of optical components, the components cooperating so that light beams from the first optical waveguide couple into the second optical waveguide but light beams from the second optical waveguide do not couple into the first optical waveguide, all of said components being situated adjacent one of the foci, further comprising at least one additional waveguide, the focussing lens means comprising a first lens element and a second lens element, an optical element being interposed between the first lens element and the second lens element for coupling light beams selectively between the optical waveguides, the non-reciprocal element being provided between the lens means and one of the second optical waveguide and additional optical waveguide.

Claim 22

A non-reciprocal optical waveguide-coupling device comprising a first optical waveguide and a second optical waveguide coupled by a common optical path, respective ends of the first and second optical waveguides being spaced apart along the optical path, focusing lens means disposed in the optical path between the respective ends of the first optical waveguide and the second optical waveguide, the focusing lens means having foci at or near respective ends of the waveguides, such that light beams leaving one of the foci will be re-focused by the focusing lens means at the other of the foci before coupling into the second optical waveguide, and a non-reciprocal element comprising a plurality of optical components, the components cooperating so that light beams from the first optical waveguide couple into the second optical waveguide but light beams from the second optical waveguide do not couple into the first optical waveguide, all of said components being situated adjacent one of the foci, further comprising at least one additional waveguide, the focussing lens means comprising a first lens element and a second lens element, an optical element being interposed between the first lens element and the second lens element for coupling light beams selectively between the optical waveguides, the non-reciprocal element being provided between the lens means and one of the second optical waveguide and additional optical waveguide.

Claim 23

A device as claimed in claim 8, further comprising at least one additional waveguide, the additional optical element comprising a wavelength dependent filter interposed between the first lens element and the second lens element, the filter providing different degrees of transmission and reflection according to wavelength of the light beams passing therethrough, such that a light beam with a first wavelength from the first optical waveguide will be coupled into the second optical waveguide and a light beam with a second wavelength from the at least one additional optical waveguide will be coupled into the second waveguide.

Claim 24

A device as claimed in claim 13, wherein the non-reciprocal element is disposed between the lens means and one of the second optical waveguide and the additional optical waveguide.