Silicon Optical Bench for Interferometric Fiber Optic Gyroscope

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Solution Overview

Problem

The high cost and complexity of manufacturing interferometric fiber optic gyros (IFOGs) due to manual fusion splicing and assembly of numerous optical components hinder the development of cost-effective and compact gyroscope systems.

Innovation Solution

Integration of passive optical and active electro-optical functions onto a single silicon substrate using self-aligning features, eliminating the need for long optical fibers and enabling automated manufacturing, resulting in a smaller, more reliable, and cost-effective IFOG design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If manual fusion splicing and assembly of optical components is used, then optical alignment precision is improved, but manufacturing complexity and cost increase significantly

Engineering Contradiction:

Improveoptical alignment precisionVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The silicon substrate provides self-aligning features through precisely formed troughs and recesses that automatically position optical components and fibers during assembly, eliminating the need for manual alignment procedures while maintaining high precision

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The silicon substrate is pre-fabricated with precisely positioned troughs, recesses, and alignment features before component assembly, enabling automated placement without manual intervention and significantly reducing manufacturing complexity

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If multiple discrete optical components are used, then optical functionality is improved, but device size and mass increase

Engineering Contradiction:

Improveoptical functionalityVSAvoiddevice mass

Core Design Contradiction:

Adaptability or versatilityVSWeight of stationary object

Solution Approach 1:

Multiple discrete optical components are integrated onto a single silicon substrate through precise positioning in etched troughs and recesses, consolidating what would be separate components into one compact unit, thereby reducing overall device size and mass while maintaining full optical functionality

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If long optical fibers with fiber pigtails are used, then optical connection flexibility is improved, but device size and reliability are worsened

Engineering Contradiction:

Improveoptical connection flexibilityVSAvoiddevice reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Long optical fibers with fiber pigtails are removed from the design entirely, replaced by direct coupling of optical components through the silicon substrate's integrated structure, eliminating reliability issues associated with fiber connections while maintaining optical functionality

Inventive Principle:

Principle #2Taking out (Extraction)

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 approach significantly reduces production costs and size while enhancing gyroscope performance by leveraging silicon optical bench technology for precise alignment and automated fabrication, addressing the limitations of conventional IFOG manufacturing methods.

Implementation Method 1

The self-aligning quality of the optical components upon placement in a suitably formed silicon substrate allows for 'passive alignment' of the components

Methodology Applied

Scientific EffectSelf-alignment: Self-Assembly

Implementation Method 2

Light may also be directed between the various optical components using free space optics such as lenses etc.

Methodology Applied

Scientific EffectLight propagation: Light

Implementation Method 3

Rotation about the axis normal to the fiber optic coil either slows or speeds the propagation of the light through the coil, resulting in a measureable shift in phase of the light

Methodology Applied

Scientific EffectSagnac effect: Sagnac Effect

Implementation Method 4

the light source is split into two beams that propagate in opposite directions through the fiber optic coil

Methodology Applied

Scientific EffectLight splitting:

Implementation Method 5

Recombining the beam produces an interference pattern indicative of the phase of the respective beams. At a detector, shifts in the interference pattern are proportional to the phase difference between the two recombined beams

Methodology Applied

Scientific EffectInterference: Interference

Data Source

PatentUS8103140B2Interferometric fiber optic gyroscope with silicon optical bench front-end

Publication Date: 2012.01.24 HONEYWELL INTERNATIONAL INC

AI summary

Method and apparatus are provided for a silicon substrate optical system for use in an interferometric fiber optic gyroscope (IFOG). A silicon substrate of the silicon substrate optical system is etched to receive optical components, including an input optical fiber, a pump source, a wavelength division multiplier, an isolator, a polarizing isolator, a beam splitting device, a PM tap coupler, a relative intensity noise (RIN) photodiode, a system photodiode, and an output optical fiber. The optical components are mounted on a silicon substrate to reduce the size and cost of the IFOG and increase reliability.