Planar lightwave circuit and optical receiver

Patent metadata

Field	Value
Publication number	US-9281901-B2
Application number	US-201314380716-A
Country	US
Kind code	B2
Filing date	Feb 18, 2013
Priority date	Mar 6, 2012
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

A planar lightwave circuit includes a substrate in which a groove being formed, the groove dividing the substrate into a first area and a second area; a first filter, a second filter, and a third filter intruded into the groove; as are formed in the first area, a first and a second waveguides formed to guide signal light and local oscillation light; a third and a fourth waveguides formed to guide signal light and local oscillation light; a first 90-degree optical hybrid; as are formed in the second area, a fifth and sixth waveguides formed to guide signal light and local oscillation light; and a second 90-degree optical hybrid.

First claim

The invention claimed is:

1. A planar lightwave circuit, comprising:
a substrate in which a groove being formed, the groove dividing the substrate into a first area and a second area;
a first filter intruded into the groove and performing polarization demultiplexing by transmission and reflection;
a second filter comprised in the first area and performing polarization demultiplexing by transmission and reflection;
a third filter comprised in the second area and performing polarization demultiplexing by transmission and reflection;
as are formed in the first area,
a first and a second waveguides formed to guide polarization-multiplexed signal light and polarization-multiplexed local oscillation light to the first filter, respectively,
a third and a fourth waveguides formed to guide signal light and local oscillation light reflected respectively by the first filter to the second filter, and
a first 90-degree optical hybrid formed to make interfere signal light and local oscillation light reflected respectively by the second filter;

as are formed in the second area,
a fifth and sixth waveguides formed to guide signal light and local oscillation light transmitted through the first filter to the third filter, respectively, and
a second 90-degree optical hybrid formed to make interfere signal light and local oscillation light transmitted respectively through the third filter.

2. The planar lightwave circuit according to claim 1 ,
wherein each of the first to third filters is one of a TE-transmissive/TM-reflective type thin film filter and a TE-reflective/TM-transmissive type thin film filter.

3. The planar lightwave circuit according to claim 2 ,
wherein the length of the third waveguide is equal to the length of the fifth waveguide.

4. The planar lightwave circuit according to claim 2 ,
wherein the length of the fourth waveguide is equal to the length of the sixth waveguide.

5. The planar lightwave circuit according to claim 2 ,
wherein the second filter is intruded into a groove formed in the first area.

6. The planar lightwave circuit according to claim 2 ,
wherein the second filter is attached on a side of the substrate in the first area.

7. The planar lightwave circuit according to claim 2 ,
wherein the third filter is intruded into a groove formed in the second area.

8. The planar lightwave circuit according to claim 1 ,
wherein the length of the third waveguide is equal to the length of the fifth waveguide.

9. The planar lightwave circuit according to claim 8 ,
wherein the second filter is intruded into a groove formed in the first area.

10. The planar lightwave circuit according to claim 8 ,
wherein the second filter is attached on a side of the substrate in the first area.

11. The planar lightwave circuit according to claim 8 ,
wherein the third filter is intruded into a groove formed in the second area.

12. The planar lightwave circuit according to claim 1 ,
wherein the length of the fourth waveguide is equal to the length of the sixth waveguide.

13. The planar lightwave circuit according to claim 12 ,
wherein the length of the fourth waveguide is equal to the length of the sixth waveguide.

14. The planar lightwave circuit according to claim 12 ,
wherein the second filter is intruded into a groove formed in the first area.

15. The planar lightwave circuit according to claim 12 ,
wherein the second filter is attached on a side of the substrate in the first area.

16. The planar lightwave circuit according to claim 1 ,
wherein the second filter is intruded into a groove formed in the first area.

17. The planar lightwave circuit according to claim 1 ,
wherein the second filter is attached on a side of the substrate in the first area.

18. The planar lightwave circuit according to claim 1 ,
wherein the third filter is intruded into a groove formed in the second area.

19. The planar lightwave circuit according to claim 1 ,
wherein the first and second 90-degree optical hybrids output a real component and an imaginary component of entered signal light, respectively.

20. An optical receiver, comprising:
a planar lightwave circuit demultiplexing each of polarization-multiplexed signal light and polarization-multiplexed local oscillation light depending on polarization, and making the signal light and the local oscillation light interfere with respect to each polarization;
a photoelectric conversion unit converting interfering light output from the planar lightwave circuit into an electrical signal;
an analog-to-digital conversion unit converting the electrical signal into a digital signal; and
a digital signal processing unit processing the digital signal,
wherein the planar lightwave circuit comprises
a substrate in which a groove being formed, the groove dividing the substrate into a first area and a second area;
a first filter intruded into the groove and performing polarization demultiplexing by transmission and reflection;
a second filter comprised in the first area and performing polarization demultiplexing by transmission and reflection;
a third filter comprised in the second area and performing polarization demultiplexing by transmission and reflection;
as are formed in the first area,
a first and a second waveguides formed to guide polarization-multiplexed signal light and polarization-multiplexed local oscillation light to the first filter, respectively,
a third and a fourth waveguides formed to guide signal light and local oscillation light reflected respectively by the first filter to the second filter, and
a first 90-degree optical hybrid formed to make interfere signal light and local oscillation light reflected respectively by the second filter;

as are formed in the second area,
a fifth and sixth waveguides formed to guide signal light and local oscillation light transmitted through the first filter to the third filter, respectively, and
a second 90-degree optical hybrid formed to make interfere signal light and local oscillation light transmitted respectively through the third filter.

Assignees

• Yamazaki Hiroyuki
• Nec Corp

Inventors

• Yamazaki Hiroyuki

Classifications

• H04B10/25

  Arrangements specific to fibre transmission · CPC title

• G02B6/12004

  Combinations of two or more optical elements · CPC title

• H04B10/60 Primary

  Receivers · CPC title

• G02B6/105

  having optical polarisation effects · CPC title

• G02B6/4213

  the intermediate optical elements being polarisation selective optical elements (G02B6/27 takes precedence) · CPC title