OPTICAL COUPLING DEVICE AND METHOD

• US 20170343739A1
• Filed: 05/24/2017
• Published: 11/30/2017
• Est. Priority Date: 05/25/2016
• Status: Active Grant

• Current Assignee: Openlight Photonics Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Bauters, Jared, Roth, Jonathan Edgar
• Granted Patent: US 10,151,883 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 6/27 with polarisation selective and adjusting means
• CPC Class Codes: G02B 6/2706 as bulk elements, i.e. free space arrangements external to a light guide, e.g. polarising beam splitters
• CPC Class Codes: G02B 6/272 comprising polarisation means for beam splitting and combining
• CPC Class Codes: G02B 6/2746 comprising non-reciprocal devices, e.g. isolators, FRM, circulators, quasi-isolators magneto-optic non-reciprocal devices G02F1/093
• CPC Class Codes: G02B 6/2766 Manipulating the plane of polarisation from one input polarisation to another output polarisation, e.g. polarisation rotators, linear to circular polarisation converters
• CPC Class Codes: G02B 6/2773 Polarisation splitting or combining
• CPC Class Codes: G02B 6/2793 Controlling polarisation dependent loss, e.g. polarisation insensitivity, reducing the change in polarisation degree of the output light even if the input polarisation state fluctuates
• CPC Class Codes: G02B 6/30 for use between fibre and thin-film device
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02B 6/4209 Optical features
• CPC Class Codes: G02B 6/4213 the intermediate optical elements being polarisation selective optical elements G02B6/27 takes precedence
• CPC Class Codes: G02B 6/4214 the intermediate optical element having redirecting reflective means, e.g. mirrors, prisms for deflecting the radiation from horizontal to down- or upward direction toward a device G02B6/4246 takes precedence

Abstract

An optical coupling device can include a first birefringent layer having opposing first and second surfaces. The first birefringent layer can split incident light received at the first surface into first and second beams. The first and second beams can have respective polarization orientations that are orthogonal to each other. The first birefringent layer can propagate the first and second beams along respective first and second paths within the first birefringent layer to the second surface. The first and second beams can be spatially separated at the second surface. A redirection layer facing the second surface of the first birefringent layer can include first and second grating couplers configured to respectively redirect the first and second beams to propagate within the redirection layer as respective third and fourth beams. In some examples, the third and fourth beams can have respective polarization orientations that are parallel to each other.

Claims

1. An optical coupling device, comprising:

a first birefringent layer having opposing first and second surfaces, the first birefringent layer configured to;

split incident light received at the first surface into first and second beams, the first and second beams having respective polarization orientations that are orthogonal to each other, and

propagate the first and second beams along respective first and second paths within the first birefringent layer to the second surface, the first and second paths being angled with respect to each other, the first and second beams having a spatial separation at the second surface; and

a redirection layer facing the second surface of the first birefringent layer, the redirection layer including first and second grating couplers configured to respectively redirect the first and second beams to propagate within the redirection layer as respective third and fourth beams along respective third and fourth paths, the third and fourth paths being angled with respect to each other.

2. The optical coupling device of claim 1, wherein the first and second grating couplers are spatially separated.

3. The optical coupling device of claim 1, wherein:

the first grating coupler redirects the first beam within a plane formed by an optic axis of the first birefringent layer and a longitudinal axis that is orthogonal to the first surface of the first birefringent layer;

the second grating coupler redirects the second beam orthogonal to the plane formed by the optic axis and the longitudinal axis; and

the third and fourth beams have respective polarization orientations that are parallel to the second surface of the first birefringent layer.

4. The optical coupling device of claim 1, wherein the first and second grating couplers each include a respective region in which a refractive index varies periodically, the periodic variations of the first and second regions being oriented orthogonal to the third and fourth paths, respectively.

5. The optical coupling device of claim 4, further comprising a focusing layer facing the first surface of the first birefringent layer, the focusing layer configured to impart a convergence onto the incident light to focus the third and fourth beams onto longitudinal ends of first and second waveguides, respectively.

6. The optical coupling device of claim 4, wherein the focusing layer includes a first surface that includes one or more curved features, and a second surface contacting the first surface of the first birefringent layer.

7. The optical coupling device of claim 4, wherein the first and second grating couplers include respective regions that include periodic variations that are curved in shape, the curvature configured to focus the third and fourth beams onto longitudinal ends of first and second waveguides, respectively.

8. The optical coupling device of claim 1, wherein:

the first birefringent layer defines a longitudinal axis as being orthogonal to the first surface; and

the first birefringent layer is formed from a material having an optic axis that is angled with respect to the longitudinal axis by an angle between zero and ninety degrees, non-inclusive.

9. The optical coupling device of claim 8, wherein the optic axis is angled at forty-five degrees with respect to the longitudinal axis.

10. The optical coupling device of claim 1, further comprising a spacer layer positioned between the first birefringent layer and the redirection layer.

11. The optical coupling device of claim 10, wherein:

the spacer layer has a first surface that contacts the second surface of the first birefringent layer; and

the spacer layer has a second surface, opposite the first surface, that contacts the redirection layer.

12. The optical coupling device of claim 1, further comprising:

a second birefringent layer having opposing first and second surfaces, the second surface of the second birefringent layer facing the first surface of the first birefringent layer; and

a half wave plate and a Faraday rotator positioned between the first birefringent layer and the second birefringent layer.

13. The optical coupling device of claim 12, wherein the half wave plate and the Faraday rotator are configured to rotate by ninety degrees a polarization orientation of light propagating from the first birefringent layer to the second birefringent layer, but not of light propagating from the second birefringent layer to the first birefringent layer.

14. The optical coupling device of claim 12, wherein the half wave plate and the Faraday rotator are configured to rotate by ninety degrees a polarization orientation of light propagating from the second birefringent layer to the first birefringent layer, but not of light propagating from the first birefringent layer to the second birefringent layer.

15. The optical coupling device of claim 1, further comprising:

a second birefringent layer having opposing first and second surfaces, the second surface of the second birefringent layer facing the first surface of the first birefringent layer; and

a Faraday rotator positioned between the first birefringent layer and the second birefringent layer.

16. The optical coupling device of claim 15, wherein the Faraday rotator is configured to:

rotate by forty-five degrees in a first direction a polarization orientation of light propagating from the first birefringent layer to the second birefringent layer, and

rotate by forty-five degrees in a second direction, opposite the first direction, a polarization orientation of light propagating from the second birefringent layer to the first birefringent layer.

17. A method, comprising:

splitting, with a first birefringent layer having opposing first and second surfaces, incident light received at the first surface into first and second beams, the first and second beams having respective polarization orientations that are orthogonal to each other;

propagating the first and second beams along respective first and second paths within the first birefringent layer to the second surface, the first and second paths being angled with respect to each other, the first and second beams having a spatial separation at the second surface; and

redirecting the first and second beams with respective first and second grating couplers, the redirected first and second beams propagating within a redirection layer facing the second surface of the first birefringent layer, the redirected first and second beams propagating along respective third and fourth paths, the third and fourth paths being angled with respect to each other.

18. The method of claim 17, further comprising imparting a convergence onto the incident light, with a focusing layer facing the first surface of the first birefringent layer, to focus the third and fourth beams onto longitudinal ends of first and second waveguides, respectively.

19. An optical coupling device, comprising:

a first birefringent layer having opposing first and second surfaces, the first birefringent layer configured to;

split incident light received at the first surface into first and second beams, the first and second beams having respective polarization orientations that are orthogonal to each other, and

propagate the first and second beams along respective first and second paths within the first birefringent layer to the second surface, the first and second paths being angled with respect to each other, the first and second beams having a spatial separation at the second surface;

a redirection layer facing the second surface of the first birefringent layer, the redirection layer including spatially separated first and second grating couplers configured to respectively redirect the first and second beams to propagate within the redirection layer as respective third and fourth beams along respective third and fourth paths, the third and fourth paths being angled with respect to each other, the third and fourth beams having respective polarization orientations that are parallel to the second surface of the first birefringent layer; and

a focusing layer facing the first surface of the first birefringent layer, the focusing layer configured to impart a convergence onto the incident light to focus the third and fourth beams onto longitudinal ends of first and second waveguides, respectively, the focusing layer including a first surface that includes one or more curved features, and a second surface contacting the first surface of the first birefringent layer.

20. The optical coupling device of claim 19, wherein:

the first birefringent layer defines a longitudinal axis as being orthogonal to the first surface; and

the first birefringent layer is formed from a material having an optic axis that is angled at forty-five degrees with respect to the longitudinal axis.