Polarization control based upon a polarization reference state

Patent metadata

Field	Value
Publication number	US-10598965-B2
Application number	US-201615011189-A
Country	US
Kind code	B2
Filing date	Jan 29, 2016
Priority date	Jan 29, 2016
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

Abstract

According to an example, a polarization control system is to manipulate polarization manipulators to output light that achieves a trajectory on a Poincaré sphere that tracks a known trajectory of a polarizer on the Poincaré sphere, in which the trajectory of the output light enables definition of a reference polarization state of the output light. The polarization control system may also manipulate an output polarization manipulator to set the output light to a predefined polarization state based upon the reference polarization state.

First claim

What is claimed is:

1. A polarization control system comprising:
polarization manipulators including an input polarization manipulator and an intermediate polarization manipulator, the input polarization manipulator to supply light into the intermediate polarization manipulator;
a processor; and
a memory on which is stored instructions that are to cause the processor to:
access, as detected by a detector, intensities of light as the input polarization manipulator is iteratively manipulated, the detector to detect the intensity of the light after the light has been emitted through the intermediate polarization manipulator and a polarizer, wherein the polarizer is to receive light from the polarization manipulators via a tap that is split from an egress fiber of the polarization manipulators;
iteratively map, onto a Poincaré sphere, the detected intensities of light as the input polarization manipulator is iteratively manipulated and the polarization of the light is rotated over time by the intermediate polarization manipulator, wherein the iteratively mapped intensities over time result in a first circle on the Poincaré sphere;
determine a misalignment between the first circle and a second circle on the Poincaré sphere, wherein the second circle is a great circle that coincides with a trajectory of the polarizer on the Poincaré sphere;
determine, from the mappings, a manipulation of the input polarization manipulator that results in the misalignment between the first circle and the second circle being at least nearly minimized;
manipulate the input polarization manipulator to modify a polarization of the light supplied into the intermediate polarization manipulator as the intermediate polarization manipulator is rotated until a determination is made that the misalignment between the first circle and the second circle is at least nearly minimized; and
define a reference polarization state of the light supplied from the polarization manipulators.

2. The polarization control system according to claim 1 , wherein the first circle identifies a maximum intensity value and a minimum intensity value of the light as the intermediate polarization manipulator rotates the polarization of the light, and wherein the instructions are further to cause the processor to:
determine a first alignment error between the maximum intensity value and a maximum power pole along the trajectory of the polarizer on the Poincaré sphere;
determine a second alignment error between the minimum intensity value and a minimum power pole along the trajectory of the polarizer on the Poincaré sphere; and
manipulate the input polarization manipulator to vary the polarization of the light supplied to the intermediate polarization manipulator until a determination is made that the first alignment error and the second alignment error are at least nearly minimized.

3. The polarization control system according to claim 2 , wherein to determine the first alignment error and the second alignment error, the processor is further to:
determine a first angle between a first virtual line extending from a center of the Poincaré sphere to the maximum power pole and a second virtual line extending from the center of the Poincaré sphere to the maximum intensity value;
determine a second angle between a third virtual line extending from the center of the Poincaré sphere to the minimum power pole and a fourth virtual line extending from the center of the Poincaré sphere to the minimum intensity value; and
wherein the processor is further to manipulate the input polarization manipulator until the first angle and the second angle are substantially minimized such that the first ring extends along a plane that is parallel to a second plane and has a substantially maximized diameter.

4. The polarization control system according to claim 1 , wherein to define the reference polarization state, the instructions are further to cause the processor to set the light directed from the intermediate polarization manipulator to be at least nearly equivalent to a maximum power pole of the polarizer along the trajectory of the polarizer on the Poincaré sphere.

5. The polarization control system according to claim 4 , further comprising:
an output polarization manipulator to receive light directed from the intermediate polarization manipulator; and
wherein the instructions are further to cause the processor to set the light directed from the output polarization manipulator to a second polarization state through manipulation of the output polarization manipulator, wherein the second polarization state is a predefined polarization state, and wherein the instructions are further to cause the processor to:
set the light directed from the output polarization manipulator to the second polarization state by manipulating the output polarization manipulator to cause intensities of light emitted through multiple polarizers that are to polarize light at different angles with respect to each other to be at fixed target levels.

6. A method for polarization control comprising:
accessing, by a processor and as detected by a detector, intensities of light as an input polarization manipulator is iteratively manipulated, the detector to detect the intensity of light after the light has been emitted through an intermediate polarization manipulator and a polarizer, the polarizer being positioned to polarize light directed to the detector from the input polarization manipulator and the intermediate polarization manipulator, the input polarization manipulator to supply light into the intermediate polarization manipulator, wherein the polarizer is to receive light from the intermediate polarization manipulator via a tap that is split from an egress fiber of the intermediate polarization manipulator;
iteratively mapping, by the processor and onto a Poincaré sphere, the detected intensities of light as the input polarization manipulator is iteratively manipulated and the polarization of the light is rotated over time by the intermediate polarization manipulator, wherein the iteratively mapped intensities over time result in a first circle on the Poincaré sphere;
determining, by the processor, a misalignment between the first circle and a second circle on the Poincaré sphere, wherein the second circle is a great circle that coincides with a trajectory of the polarizer on the Poincaré sphere;
determining, by the processor and from the mappings, a manipulation of the input polarization manipulator that results in the misalignment between the first circle and the second circle being at least nearly minimized;
manipulating, by the processor, the input polarization manipulator to modify a polarization of the light supplied into the intermediate polarization manipulator as the intermediate polarization manipulator is rotated until a determination is made that the misalignment between the first circle and the second circle is at least nearly minimized; and
defining, by the processor, a reference polarization state of the light output from the input and the intermediate polarization manipulators.

7. The method according to claim 6 , wherein the first circle identifies a maximum intensity value and a minimum intensity value of the light as the intermediate polarization manipulator rotates the polarization of the light, said method further comprising:
determining a first alignment error between the maximum intensity value and a maximum power pole along the trajectory of the polarizer on the Poincaré sphere;
determining a second alignment error between the minimum intensity value and a minimum power pole along the trajectory of the polarizer on the Poincaré sphere; and
wherein iteratively manipulating the input polarization manipulator further comprises iteratively

Assignees

• Viavi Solutions Inc

Inventors

• Philipson Joshua
• Wagner Chris
• Tessaro Grant
• Adams Robert Matthew

Classifications

• G02B6/2713

  cascade of polarisation selective or adjusting operations · CPC title

• G02F1/0136 Primary

  for the control of polarisation, e.g. state of polarisation [SOP] control, polarisation scrambling, TE-TM mode conversion or separation (G02F1/0353 takes precedence) · CPC title

• G02B6/276

  Removing selected polarisation component of light, i.e. polarizers · CPC title

• G01J4/04

  Polarimeters using electric detection means (G01J4/02 takes precedence) · CPC title

• G02F1/0121

  Operation of devices; Circuit arrangements, not otherwise provided for in this subclass · CPC title