120-Degree Phase Separation for Optical Phase Demodulation

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Solution Overview

Problem

Current fiber optic sensing systems face issues with receiver saturation and noise in optical phase measurements due to increased amplification and common mode signal components, leading to inaccurate phase measurements.

Innovation Solution

The implementation of a fiberoptic coupler with balanced photo-detectors to generate three optical interferometry signals with mutual phase separations of 120°, which are then processed by balanced photo-detectors to produce electrical difference signals, reducing noise and increasing the signal-to-noise ratio and dynamic range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If increased amplification is used to overcome attenuation, then signal strength is improved, but receiver saturation and noise increase

Engineering Contradiction:

Improvesignal strengthVSAvoidmeasurement accuracy

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The optical signal is divided into three separate interferometry signals with 120-degree phase separation, which are then processed by balanced photo-detectors. This segmentation allows the common mode signal to be rejected while preserving the differential signal information, solving the saturation and noise problem without sacrificing signal strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The balanced photo-detectors extract and reject the common mode signal component from the optical receiver output. By subtracting the common mode component, the system removes the source of saturation and noise that would otherwise limit measurement accuracy, while maintaining the useful signal.

Inventive Principle:

Principle #2Taking out (Extraction)

2Quantity of substance

If common mode signal component is present, then optical receiver dynamic range is consumed, but measurement precision deteriorates

Engineering Contradiction:

Improvedynamic range consumptionVSAvoidoptical phase measurement accuracy

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The balanced photo-detectors specifically extract and remove the common mode signal component from the total signal. This extraction prevents the common mode signal from consuming dynamic range while simultaneously eliminating its contribution to measurement noise, thereby improving optical phase measurement accuracy.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The common mode signal, which was previously harmful by consuming dynamic range and adding noise, is converted into a useful reference. The balanced photo-detectors use the common mode component as a reference to subtract from the total signal, transforming it from a harmful element into a tool for improving measurement precision.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If 120 degree phase separation is implemented, then signal-to-noise ratio is improved, but device complexity increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidinterferometry signal generation

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The 3x3 fiberoptic coupler performs multiple functions simultaneously: it divides the input optical signal into three separate paths, introduces the required 120-degree phase separations, and combines the signals for balanced detection. This multi-functionality achieves the signal-to-noise ratio improvement without proportionally increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration decreases the likelihood of receiver saturation, increases the useful dynamic range, and enhances measurement accuracy by lowering the noise floor, resulting in more precise optical phase measurements.

Implementation Method 1

a receiver having a fiberoptic coupler producing three optical interferometry signals having mutual phase separations of 120°

Methodology Applied

Scientific EffectInterference: Interference

Implementation Method 2

balanced photo-detectors that each produce an electrical difference signal based on a respective pair of said optical interferometry signals

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentUS10101182B2Interferometric high fidelity optical phase demodulation using 120 degree phase separation

Publication Date: 2018.10.16 HALLIBURTON ENERGY SERVICES INC

AI summary

An illustrative interferometric system with high-fidelity optical phase demodulation includes a receiver having a fiberoptic coupler that produces optical interferometry signals having mutual phase separations of 120° and balanced photo-detectors that each produce an electrical difference signal based on a respective pair of said optical interferometry signals. The system further includes circuitry that converts the electrical difference signals into measurements of an interferometric phase.