Integrated optical circulator enabling polarization diversity

Patent metadata

Field	Value
Publication number	US-11340468-B2
Application number	US-202016985301-A
Country	US
Kind code	B2
Filing date	Aug 5, 2020
Priority date	Dec 6, 2017
Publication date	May 24, 2022
Grant date	May 24, 2022

Abstract

A photonic integrated circulator can be fabricated by including a plurality of polarizing beam splitters and optical polarization rotators such that two copies of the optical signal are output at a receiver in substantially aligned polarization states. The circulator can be used for facilitating bi-directional communications between photonic integrated circuit devices, which are inherently polarization sensitive, while reducing signal loss.

First claim

The invention claimed is:

1. An integrated optical circulator enabling polarization diversity, the integrated optical circulator comprising:
a first port configured to receive a first optical signal;
a second port configured to transmit the first optical signal received at the first port and also configured to receive a second optical signal;
a first polarization beam splitter configured to:
receive the second optical signal;
split the second optical signal into a first optical signal component and a second optical signal component;
direct the first optical signal component towards a first reflective surface,
and

direct the second optical signal component through a first optical polarization rotator;

a second polarization beam splitter configured to receive the second optical signal component after the second optical signal component passes through the first optical polarization rotator, wherein the second polarization beam splitter does not receive the first optical signal component; and
a third port configured to transmit the first optical signal component of the second optical signal after it passes through a second optical polarization rotator, a fourth port transmitting the second optical signal component at a second polarization state substantially aligned with a first polarization state.

2. The integrated optical circulator of claim 1 , further comprising the fourth port configured to transmit the second optical signal component after it passes through the first optical polarization rotator, the third port transmitting the first optical signal component at the first polarization state.

3. The integrated optical circulator of claim 1 , wherein the first reflective surface is configured to further direct the first optical signal component to pass through the first optical polarization rotator.

4. The integrated optical circulator of claim 1 , wherein the second polarization beam splitter is further configured to direct the second optical signal component towards a second reflective surface, the second reflective surface directing the second optical signal component towards a third optical polarization rotator.

5. The integrated optical circulator of claim 1 wherein the first optical polarization rotator is a half-wave plate.

6. The integrated optical circulator of claim 1 , wherein the first optical polarization rotator is a continuous optical polarization rotator.

7. The integrated optical circulator of claim 1 , wherein:
a fifth port is configured to receive a third optical signal;
a sixth port is configured to transmit the third optical signal received at the fifth port and also configured to receive a fourth optical signal;
the first polarization beam splitter is further configured to:
receive the fourth optical signal;
split the fourth optical signal into a third optical signal component and a fourth optical signal component;
direct the third optical signal component towards the first reflective surface,
wherein the first reflective surface is configured to further direct the third optical signal component to pass through the first optical polarization rotator; and
direct the fourth optical signal component through the first optical polarization rotator;

the second polarization beam splitter is configured to receive the fourth optical signal component after the fourth optical signal component passes through the first optical polarization rotator, and direct the fourth optical signal component towards a second reflective surface, the second reflective surface directing the fourth optical signal component towards the third optical polarization rotator;
a seventh port configured to transmit the third optical signal component after it passes through the first optical polarization rotator, the seventh port transmitting the third optical signal component at a first polarization state; and
an eighth port configured to transmit the fourth optical signal component after it passes through the third optical polarization rotator, the eighth port transmitting the fourth optical signal component at a second polarization state.

8. The integrated optical circulator of claim 1 , wherein at least one additional optical polarization rotator is optically coupled to either the first optical polarization rotator, the second optical polarization rotator, or both.

9. The integrated optical circulator of claim 8 , wherein the at least one additional optical polarization rotator is a Faraday rotator.

10. The integrated optical circulator of claim 1 , further comprising a third reflective surface, wherein the third reflective surface is a polarizing beam splitter.

11. The integrated optical circulator of claim 1 , further comprising a fourth reflective surface, wherein the forth reflective surface is a polarizing beam splitter.

12. The integrated optical circulator of claim 1 , wherein the first polarization state and second polarization state are p-polarizations.

13. The integrated optical circulator of claim 1 , wherein the first transmitted signal is p-polarized.

14. The integrated optical circulator of claim 1 , wherein the first polarizing beam splitter splits the second optical signal into the first optical signal component and the second optical signal component carrying orthogonal polarizations.

15. An integrated optical circulator enabling polarization diversity, the integrated optical circulator comprising:
a first port configured to receive a first optical signal;
a third port configured to transmit the first optical signal received at the first port and also configured to receive a second optical signal;
a first polarization beam splitter configured to:
receive the second optical signal;
split the second optical signal into a first optical signal component and a second optical signal component;
direct the first optical signal component towards a first reflective surface,
and

direct the second optical signal component through a first optical polarization rotator; and

a second polarization beam splitter configured to receive the second optical signal component after the second optical signal component passes through the first optical polarization rotator,
wherein the second polarization beam splitter does not receive the first optical signal component, and
wherein the second polarization beam splitter is further configured to direct the second optical signal component towards a second reflective surface, the second reflective surface directing the second optical signal component towards a second optical polarization rotator.

16. The integrated optical circulator of claim 15 , further comprising a third port configured to transmit the first optical signal component after it passes through the first optical polarization rotator, the third port transmitting the first optical signal component at a first polarization state.

17. The integrated optical circulator of claim 15 , further comprising a fourth port configured to transmit the second optical signal component of the second optical signal after it passes through the second optical polarization rotator, the fourth port transmitting the second optical signal component at a second polarization state substantially aligned with a first polarization state.

18. The integrated optical circulator of claim 17 , wherein the first polarization state and second polarization state are p-polarizations.

19. The integrated optical circulator of claim 15 , wherein the first reflective surface is configured to further direct the first optical signal component to pass

Assignees

• Google Llc

Inventors

• Urata Ryohei
• Verslegers Lieven
• Liu Hong
• Wang Daoyi

Classifications

• G02B5/3083

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title

• G02B6/105

  having optical polarisation effects · CPC title

• G02B6/4246

  Bidirectionally operating package structures · CPC title

• G02B27/283 Primary

  used for beam splitting or combining · CPC title

• G02F1/093

  used as non-reciprocal devices, e.g. optical isolators, circulators (G02F1/0955 takes precedence) · CPC title