Polarization control based upon a polarization reference state

Patent metadata

Field	Value
Publication number	US-2017219853-A1
Application number	US-201615011189-A
Country	US
Kind code	A1
Filing date	Jan 29, 2016
Priority date	Jan 29, 2016
Publication date	Aug 3, 2017
Grant date	—

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:
a processor; and a memory on which is stored instructions that are to cause the processor to:
access a known trajectory of a polarizer on a Poincaré sphere;
manipulate polarization manipulators to output light that achieves a trajectory on the Poincaré sphere that at least nearly tracks the known trajectory of the polarizer; and
define a reference polarization state of the output light from the achieved trajectory.

2 . The polarization control system according to claim 1 , wherein the polarization manipulators include an input polarization manipulator and an intermediate polarization manipulator, wherein the instructions are further to cause the processor to:
map, onto the Poincaré sphere, intensities of light directed from the intermediate polarization manipulator and emitted through the polarizer resulting from a polarization of the light being rotated over time by the intermediate polarization manipulator, wherein the 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 the known trajectory of the polarizer; and manipulate the input polarization manipulator from which the light is supplied into the intermediate polarization modulator to modify the polarization of the light directed through the polarizer 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.

3 . The polarization control system according to claim 2 , wherein a detector is to detect the intensity of the light after the light has been emitted through the polarizer, and wherein the instructions are further to cause the processor to:
access intensities of the light detected by the detector as the input polarization manipulator is iteratively manipulated; iteratively map, onto the 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; and determine, from the mappings, the manipulation of the input polarization manipulator that results in the misalignment between the first circle and the second circle being at least nearly minimized.

4 . 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 known 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 known 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.

5 . The polarization control system according to claim 4 , 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 the second plane and has a substantially maximized diameter.

6 . 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 known trajectory of the polarizer on the Poincaré sphere.

7 . The polarization control system according to claim 6 , 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.

8 . A method for polarization control comprising:
accessing a known trajectory of a polarizer on a Poincaré sphere that graphically represents polarization states; manipulating polarization manipulators to output light that achieves a trajectory on the Poincaré sphere that at least nearly tracks the known trajectory of the polarizer; and defining a reference polarization state of the output light from the achieved trajectory.

9 . The method according to claim 8 , wherein the polarization manipulators include an input polarization manipulator and an intermediate polarization manipulator, the method further comprising:
determining, on the Poincaré sphere, a first circle that corresponds to values of a plurality of intensities of light as polarization of the light is rotated by an intermediate polarization manipulator and detected by a detector following emission of the light through the polarizer, wherein the light is inputted to the intermediate polarization manipulator from an input polarization manipulator; 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 maps to a rate of polarization change of the polarizer and coincides with the known trajectory of the polarizer; and iteratively manipulating, by the processor, the input polarization manipulator to vary a polarization of the light supplied into the intermediate polarization manipulator to modify the polarization of the light directed through the polarizer as the intermediate polarization manipulator is rotated until a determination is made that the first circle at least nearly overlaps the second circle.

10 . The method according to claim 9 , 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 known trajectory of the polarizer on the Poincaré sphere; determining a second alignment error bet

Assignees

• Viavi Solutions Inc

Inventors

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

Classifications

• G01J4/04

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

• G02B6/2713

  cascade of polarisation selective or adjusting operations · CPC title

• G02B6/276

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

• G02F1/0121

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