High-Resolution Measurement of Fiber Length Change with Optical Low-Coherence Reflectometer Based on a Fiber-Ring Structure

A simple approach is proposed and experimentally demonstrated to improve measurement precision of short fiber length or fiber length change with an optical low-coherence reflectometer (OLCR). A fiber-ring structure composed of a coupler and a circulator is introduced in the test arm of OLCR to virtually multiply the length of the fiber under test. By measuring the multiplied fiber length under test, the measurement precision is enhanced. A precision enhancement of 10 times is successfully achieved.