Distributed characterization system and method of variations of the refractive index of an optical fiber.

New and innovative aspects

The present invention meets the need of the prior art as a technique capable of measuring of variations of the refractive index of a fiber, in a range of long extent and high temporal resolution, providing flexibility spatial resolution as well; and in the dynamic range of the index variations, low complexity, high sensitivity and stability against environmental changes.

Nothing like this invention has been found in databases of patents or scientific literature consulted.

Main advantages of its use

The invention provides a characterization of high spatial resolution, sensitivity and speed, requiring a single pulse to characterize a state of the optical fiber instead of using frequency sweeps in multiple pulses.

Limited number of elements and therefore reduced cost of the sensor system.

Specifications

The present invention proposes a system and a method for distributed measuring of local variations of refractive index between different states of an optical fiber, for comparison of amplitude profiles of Rayleigh scattering, generated in two different states of the fiber by two light pulses of snapshot frequency, variable in time and invariant between pulses.

1. The system consists in:

- Emission media that generate optical pulses with a same profile of instantaneous frequency, being this frequency variable along a single pulse.

-Receiving media that receive the backscattered optical signals, connected to the same end of the fiber of the emission medias (by an optical circulator)

- Detection media that measure, at least, the amplitude profile of the backscattered optical signals.

- Computing media that calculate the local variations of refractive index, occurring between different states of the optical fiber.

The system further comprises, distributed expansion means that amplify the signal emitted into the optical fiber, allowing the characterization of longer lengths of fiber.

1. The method consists in:

• Generate and transmit the optical signals described through a fiber under test.
• Receive the backscattered optical signals generated in the fiber at the same end of the fiber tan the transmission
• Measure the amplitude profiles of the backscattered optical signals, using a photodetector whose exit serves as an entrance to a digital mean, such as an oscilloscope.
• The method may include, the measuring of the amplitud and frequency profiles of the pulse optical signal or use some other stored.
• Calculate the local variations of refractive index of the fiber occurred between different states of the fiber.

1. Computer program that implements the method described, when it runs on a suitable processor of the signal

With the system, method and computer program of the invention, a measure of the local variations of refractive index of the fiber, with high spatial resolution, high sensitivity and high speed is obtained.

Applications

- Telecommunications companies, particularly in the industrial area of sensing and distributed characterization of optical fibers.

- Civil engineering (measures of vibration / intrusion around a perimeter), energy (temperature measurements along a gas pipeline) and the environment

Intellectual property status

The patent has been applied to the Spanish Patent and Trademark Office with date 30 November 2015 and application number P201531736

Current development status

The technology is a development phase but available for demonstration

Desired business relationship

The research groups seeks to reach licensing, cooperation or commercial agreements with telecommunications companies, particularly in the industrial area of sensing and distributed characterization of optical fibers.

There is also a direct application to sector as civil engineering (measures of vibration / intrusion around a perimeter), energy (temperature measurements along a gas pipeline) and the environment.