Free space single-mode fibers and fiber components for fiber sensor applications

Patent metadata

Field	Value
Publication number	US-9448116-B2
Application number	US-201113149208-A
Country	US
Kind code	B2
Filing date	May 31, 2011
Priority date	Jan 19, 2011
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

This invention revealed and demonstrated a method of measuring and deriving a Jones Matrix of a fiber or fiber component, and to compensate the fiber or fiber component such that the fiber or fiber component plus the compensated optical circuit act as if an Unitary Matrix free space condition. In this way, all compensated fibers or fiber components act the same no matter what their original conditions are. It greatly enhances the fiber or fiber component repeatability and stability throughout the fiber or fiber component production line. The compensated circuit for Unitary Matrix can be applied externally or internally.

First claim

What is claimed is:

1. An optical compensation method comprising the following steps of:
(a) providing an input light having a given polarization state from a broadband laser with a full width at half maximum greater than or equal to 5nm, and a wavelength range being one selected from the group consisting of 1450˜1650nm, 1250˜1400nm, and 750˜900nm to a fiber optical sensor having a fiber sensing element;
(b) obtaining an output light after the input light passes through the fiber sensing element of the fiber optical sensor;
(c) measuring a polarization state of the output light;
(d) obtaining, from the polarization state of the output light and the given polarization state of the input light, a set of equivalent optical parameters representative of the fiber sensing element of the fiber optical sensor, wherein the set of equivalent optical parameters is established by, but not limited to, one of the following three sets of parameters, comprising:
(i) three equivalent optical parameters including a principal axis angle (α), a phase retardation (β) and an optical rotation angle (γ);
(ii) five equivalent optical parameters including a principal axis angle (α), a phase retardation (β), a diattenuation axis angle (θ d ), a diattenuation (D), and the optical rotation angle (γ); and
(iii) more than five equivalent optical parameters including at least a principal axis angle (α), a phase retardation (β) and an optical rotation angle (γ);
(e) obtaining solutions of a set of variable parameters by solving an equation that a product of multiplying a compensation matrix comprising the set of variable parameters by an equivalent matrix formed by the set of equivalent optical parameters is equal to a unit matrix; and
(f) using the solutions of the set of variable parameters to apply an optical compensation of the polarization state to one of the input light and the output light.

2. The method as claimed in claim 1 , wherein the optical compensation is carried out by an optical compensation assembly to make the polarization state of the output light remain the same as that of the input light.

3. The method of claim 1 performed during a production of fiber coil assembly modules, including at least a fiber coil, as part of fiber optic sensor systems.

Assignees

• Lo Yu-Lung
• Liu Ren-Young
• Yen Chih-Chung
• Chung Yi-Fan
• Nat Applied Res Laboratories

Inventors

• Lo Yu-Lung
• Liu Ren-Young
• Yen Chih-Chung
• Chung Yi-Fan

Classifications

• G01J4/04 Primary

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

• G01C19/72

  with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers · CPC title

• G02B6/2793

  Controlling polarisation dependent loss, e.g. polarisation insensitivity, reducing the change in polarisation degree of the output light even if the input polarisation state fluctuates · CPC title

• G01J4/00 Primary

  Measuring polarisation of light · CPC title