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

摘要

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.

主权项

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 (θd), 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.