Optical Fiber Modulation for Underwater Wireless Communication

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Solution Overview

Problem

Communication with underwater vehicles is limited by signal attenuation in water, leading to short operational ranges and low bandwidth capacity, and the use of tethers restricts mobility and range.

Innovation Solution

A communication system utilizing modulated waves, such as mechanical waves, applied to an optical fiber, where a phase-sensitive OTDR device detects reflected light to encode and decode signals, enabling high-bandwidth, long-range wireless communication between an underwater vehicle and a receiving system without significantly affecting the underwater acoustic environment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a tether with optical fiber is used to connect underwater vehicle to receiving system, then signal attenuation is reduced, but range and mobility of underwater vehicle are limited

Engineering Contradiction:

Improvesignal attenuationVSAvoidrange and mobility

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent extracts the communication function from the physical tether connection. Instead of requiring a continuous physical connection between the underwater vehicle and surface station, the system uses acoustic waves to modulate the optical fiber remotely, allowing the vehicle to communicate without being tethered. This resolves the contradiction by maintaining reliable signal transmission while eliminating the mobility and range limitations imposed by physical tethers.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces acoustic waves as an intermediary medium to transfer information to the optical fiber. The acoustic waves serve as a mediator that can penetrate water and mechanically modulate the optical fiber without requiring direct physical connection. This intermediary approach enables reliable communication while allowing the underwater vehicle to move freely without tether constraints.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If sonar and sound-based communication techniques are used, then communication in water is achieved, but bandwidth capacity is low

Engineering Contradiction:

Improvecommunication in waterVSAvoidbandwidth capacity

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent replaces acoustic/mechanical wave-based communication (sonar) with optical-based communication. Instead of using sound waves that are limited in bandwidth, the system uses optical fibers to transmit light signals, achieving significantly higher bandwidth capacity. The acoustic waves are only used for remote modulation of the optical fiber, not for direct communication, thus resolving the bandwidth limitation while maintaining adaptability to underwater environments.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If mechanical waves are applied to optical fiber at high frequency, then data rate is increased, but attenuation in water increases

Engineering Contradiction:

Improvedata rateVSAvoidattenuation in water

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent applies parameter changes by selecting specific frequency ranges for the acoustic waves. Instead of using any frequency, the system uses acoustic waves in the frequency range of 1-100 Hz, which has been optimized to achieve adequate attenuation in water while still enabling sufficient modulation of the optical fiber for high data rate communication. This parameter optimization resolves the contradiction between data rate and energy loss.

Inventive Principle:

Principle #35Parameter changes

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 solution allows for high-data-rate, long-distance wireless communication between an underwater vehicle and a remote station, utilizing existing optical fiber infrastructure, while minimizing environmental impact by selecting wave frequencies with high attenuation in water.

Implementation Method 1

a phase-sensitive optical time domain reflectometry (OTDR) device may be coupled to the optical fiber and may detect reflected light that is responsive to a disturbance applied to the optical fiber

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

the mechanical waves may change a reflection signature of the optical fiber by disturbing impurities within the optical fiber that cause the reflection of light

Methodology Applied

Scientific EffectMechanical vibration: Vibration

Data Source

PatentUS8682173B1Communication using modulated waves applied to an optical fiber

Publication Date: 2014.03.25 THE BOEING CO

AI summary

A particular method includes applying light pulses to an optical fiber and receiving backscattered light at a phase-sensitive optical time domain reflectometry (OTDR) device. The backscattered light includes portions of the applied light pulses that are backscattered by the optical fiber. The method also includes determining a difference between the backscattered light and a backscatter pattern associated with the optical fiber. The method also includes determining a communication signal encoded in the backscattered light based on the difference, where the communication signal is encoded in the backscattered light responsive to mechanical waves applied to the optical fiber at a location remote from the phase-sensitive OTDR device.