Field-programmable optical component

Patent metadata

Field	Value
Publication number	US-9753224-B2
Application number	US-201615080170-A
Country	US
Kind code	B2
Filing date	Mar 24, 2016
Priority date	Mar 25, 2015
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

Methods are known for implementing general optical functions using wave splitters. However, these methods rely on these wave splitters having maximal extinction ratio, which is difficult to achieve in practice. The present invention provides methods for automatically adjusting wave splitters to provide maximal extinction ratio.

First claim

The invention claimed is:

1. A method for adjusting an interferometer to have maximum extinction ratio, the method comprising:
providing an interferometer comprising a first wave splitter having an input I 1 - 1 and having outputs O 1 - 1 and O 1 - 2 , a phase adjuster, and a second wave splitter having inputs I 2 - 1 and I 2 - 2 and having outputs O 2 - 1 and O 2 - 2 ;
wherein O 1 - 1 is connected to I 2 - 1 and O 1 - 2 is connected to I 2 - 2 , wherein the phase adjuster provides a relative phase θ between these two connections;
wherein the first wave splitter has an adjustable first split error E 1 =R 1 −½, wherein R 1 is a power transmittance from I 1 - 1 to O 1 - 1 ;
wherein the second wave splitter has an adjustable second split error E 2 =R 2 −½, wherein R 2 is a power transmittance from I 2 - 1 to O 2 - 1 ;
wherein the interferometer has a bar state where θ is selected to maximize transmission from I 1 - 1 to O 2 - 1 relative to transmission from I 1 - 1 to O 2 - 2 ;
wherein the interferometer has a cross state where θ is selected to maximize transmission from I 1 - 1 to O 2 - 2 relative to transmission from I 1 - 1 to O 2 - 1 ;
performing an automatic adjustment that includes an alternating sequence of the following steps:
i) adjusting E 1 and E 2 to optimize cross state performance, wherein changes to E 1 and E 2 are linked such that their values change by substantially equal amounts;
ii) adjusting E 1 and E 2 to optimize bar state performance, wherein changes to E 1 and E 2 are linked such that their values change by substantially equal and opposite amounts.

2. Optical apparatus comprising:
an interferometer comprising a first wave splitter having an input I 1 - 1 and having outputs O 1 - 1 and O 1 - 2 , a phase adjuster, and a second wave splitter having inputs I 2 - 1 and I 2 - 2 and having outputs O 2 - 1 and O 2 - 2 ;
wherein O 1 - 1 is connected to I 2 - 1 and O 1 - 2 is connected to I 2 - 2 , wherein the phase adjuster provides a relative phase θ between these two connections;
wherein the first wave splitter has an adjustable first split error E 1 =R 1 −½, wherein R 1 is a power transmittance from I 1 - 1 to O 1 - 1 ;
wherein the second wave splitter has an adjustable second split error E 2 =R 2 −½, wherein R 2 is a power transmittance from I 2 - 1 to O 2 - 1 ;
wherein the interferometer has a bar state where θ is selected to maximize transmission from I 1 - 1 to O 2 - 1 relative to transmission from I 1 - 1 to O 2 - 2 ;
wherein the interferometer has a cross state where θ is selected to maximize transmission from I 1 - 1 to O 2 - 2 relative to transmission from I 1 - 1 to O 2 - 1 ;
wherein the apparatus is configured to perform an automatic adjustment that includes an alternating sequence of the following steps:
i) adjusting E 1 and E 2 to optimize cross state performance, wherein changes to E 1 and E 2 are linked such that their values change by substantially equal amounts;
ii) adjusting E 1 and E 2 to optimize bar state performance, wherein changes to E 1 and E 2 are linked such that their values change by substantially equal and opposite amounts.

3. The apparatus of claim 2 , wherein the first wave splitter comprises a waveguide Mach-Zehnder interferometer having a fabricated split ratio in a range from 15:85 to 85:15.

4. The apparatus of claim 2 , wherein the second wave splitter comprises a waveguide Mach-Zehnder interferometer having a fabricated split ratio in a range from 15:85 to 85:15.

5. The apparatus of claim 2 , further comprising a tap detector configured to monitor power emitted from O 2 - 1 .

6. The apparatus of claim 2 , further comprising a tap detector configured to monitor power emitted from O 2 - 2 .

7. The apparatus of claim 2 , wherein the apparatus is configured to automatically halt the alternating sequence of the steps (i) and (ii) when a stopping condition is satisfied.

8. The apparatus of claim 7 , wherein the stopping condition is reaching a predetermined maximum number of iterations.

9. The apparatus of claim 7 , wherein the stopping condition is measure power going below a predetermined minimum power threshold during power minimization.

10. The apparatus of claim 7 , wherein the stopping condition is having a change in measured power between two successive iterations be below a predetermined threshold during power maximization.

11. The apparatus of claim 2 , wherein the first wave splitter has an input I 1 - 2 .

Assignees

• Univ Leland Stanford Junior

Inventors

• Miller David A B

Classifications

• G01B9/02015

  characterised by the beam path configuration · CPC title

• G01B9/02075 Primary

  of particular errors · CPC title

• G02B6/29395 Primary

  configurable, e.g. tunable or reconfigurable (switching G02B6/35) · CPC title

• G02B6/2935

  Mach-Zehnder configuration, i.e. comprising separate splitting and combining means · CPC title

• G02B6/29355

  Cascade arrangement of interferometers · CPC title