Adiabatic polarization rotator combiner

Patent metadata

Field	Value
Publication number	US-10401566-B2
Application number	US-201715826673-A
Country	US
Kind code	B2
Filing date	Nov 29, 2017
Priority date	Nov 29, 2016
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A system may include a polarization rotator combiner. The polarization rotator combiner may include a first stage, a second stage, and a third stage. The first stage may receive a first component of light with a TE00 polarization and a second component of light with the TE00 polarization. The first stage may draw optical paths of the first and second components together. The second stage may receive the first component and the second component from the first stage. The second stage may convert the polarization of the second component from the TE00 polarization to a TE01 polarization. The third stage may receive the first component and the second component from the second stage. The third stage may convert polarization of the second component from the TE01 polarization to a TM00 polarization. The third stage may output the first component and output the second component.

First claim

What is claimed is:

1. A system that includes a polarization rotator combiner (PRC), the PRC comprising:
a first stage including:
a first silicon nitride (SiN) waveguide; and
a second SiN waveguide;

a second stage of the PRC including:
a first SiN S-bend waveguide coupled with the first SiN waveguide at an input end of the first SiN S-bend waveguide; and
a second SiN S-bend waveguide coupled with the second SiN waveguide at an input end of the second SiN S-bend waveguide;

a third stage of the PRC including:
a first SiN strip waveguide continuous with the first SiN S-bend waveguide; and
a second SiN strip waveguide continuous with the second SiN S-bend waveguide and spaced apart from the first SiN strip waveguide by a gap width w gap , the second SiN strip waveguide tapering inward along a light propagation direction from a first end of the second SiN strip waveguide to a second end of the second SiN strip waveguide; and

a fourth stage of the PRC including a SiN rib waveguide continuous with the first SiN strip waveguide, the SiN rib waveguide including a rib and a ridge that extends vertically above the rib, the SiN rib waveguide having a rib width w rib , wherein the rib width w rib varies along at least a portion of a length of the SiN rib waveguide,
wherein the system further comprises a first silicon (Si) waveguide with a tapered end adiabatically coupled to the first SiN waveguide and a second Si waveguide with a tapered end adiabatically coupled to the second SiN waveguide, wherein the first SiN waveguide is positioned above the first Si waveguide and wherein the second SiN waveguide is positioned above the second Si waveguide.

2. The system of claim 1 , wherein each of the first SiN waveguide, the second SiN waveguide, the first SiN S-bend waveguide, the second SiN S-bend waveguide, the first SiN strip waveguide, the second SiN strip waveguide, and the SiN rib waveguide comprises a core of SiN surrounded by a cladding of silicon dioxide (SiO 2 ).

3. The system of claim 1 , wherein the first SiN waveguide is positioned 50-100 nanometers (nm) above the first Si waveguide and wherein the second SiN waveguide is positioned 50-100 nm above the second Si waveguide.

4. The system of claim 1 , further comprising:
a first Mach Zehnder Delay Line Interferometer (DLI) having two inputs and an output, the output optically coupled to the first Si waveguide; and
a second Mach Zehnder Delay Line Interferometer (DLI) having two inputs and an output, the output optically coupled to the second Si waveguide.

5. The system of claim 1 , wherein the input end of the first SiN S-bend waveguide and the input end of the second SiN S-bend waveguide are separated by a distance of at least 10 micrometers (μm).

6. The system of claim 1 , wherein the gap width w gap between the first and second SiN strip waveguides is constant and no more than 400 nm.

7. The system of claim 1 , wherein the second SiN strip waveguide tapers inward along the light propagation direction from the first end of the second SiN strip waveguide to the second end of the second SiN strip waveguide with a linear or exponential shape.

8. The system of claim 1 , wherein the SiN rib waveguide in the fourth stage has a top width of w SiN and wherein the top width w SiN is relatively constant near the third stage of the PRC and tapers inward near an end of the SiN rib waveguide opposite the third stage of the PRC.

9. The system of claim 8 , wherein the top width w SiN is 3 micrometers (μm) at a beginning of the fourth stage and tapers inward near the end of the SiN rib waveguide opposite the third stage of the PRC to a top width w SiN of 2 μm or less.

10. A system that includes a polarization rotator combiner (PRC), the PRC comprising:
a first stage including:
a first silicon nitride (SiN) waveguide; and
a second SiN waveguide that extends parallel to the first SiN waveguide through the first stage and that is spaced apart from the first SiN waveguide by a first distance;

a second stage of the PRC including:
the first SiN waveguide that approaches the second SiN waveguide through the second stage;
the second SiN waveguide that approaches the first SiN waveguide through the second stage;

a third stage of the PRC including:
the first SiN waveguide; and
the second SiN waveguide that extends parallel to the first SiN waveguide through the third stage and that is spaced apart from the first SiN waveguide by a gap width w gap that is less than the first distance, wherein the second SiN waveguide tapers inward along a light propagation direction from a beginning to an end of the third stage and terminates at the end of the third stage; and

a fourth stage of the PRC including the first SiN waveguide, the first SiN waveguide including a rib and a ridge that extends vertically above the rib in the fourth stage, the rib having a rib width w rib that varies along at least a portion of a length of the first SiN waveguide within the fourth stage,
wherein the system further comprises a first silicon (Si) waveguide with a tapered end adiabatically coupled to the first SiN waveguide at an input of the first stage and a second Si waveguide with a tapered end adiabatically coupled to the second SiN waveguide at the input of the first stage, wherein the first SiN waveguide is positioned above the first Si waveguide and wherein the second SiN waveguide is positioned above the second Si waveguide.

11. The system of claim 10 , wherein the rib of the first waveguide PRC is further included in each of the first, second, and third stages.

12. The system of claim 11 , wherein:
the ridge comprises a first ridge;
the first waveguide comprises the first ridge that extends above the rib and that extends through each of the first, second, third, and fourth stages;
the second waveguide comprises a second ridge that extends above the rib and that extends through each of the first, second, and third stages;
the first ridge and the second ridge extend parallel to one another and are spaced apart from each other by the first distance through the first stage;
the first ridge and the second ridge expand toward each other through the second stage; and
the first ridge and the second ridge extend parallel to one another and are spaced apart from each other by the gap width w gap in the third stage.

13. The system of claim 11 , wherein:
the rib tapers outward through the first stage to a first width;
the rib has the first width as a constant width through both the second stage and the third stage;
the rib tapers from the first width inward for a first portion of the fourth stage to a second width, has the second width as a constant width for a second portion of the fourth stage, and tapers from the second width inward for a third portion of the fourth stage.

Assignees

• Finisar Corp

Inventors

• Park Bryan
• Mahgerefteh Daniel
• Yong Zheng
• Poon Joyce Kai See

Classifications

• G02B6/14

  Mode converters · CPC title

• G02B2006/12152

  Mode converter · CPC title

• G02B6/126 Primary

  using polarisation effects {(G02B6/1226 takes precedence)} · CPC title

• G02B2006/1215

  Splitter · CPC title

• G02B2006/12035

  Materials · CPC title