Sub-wavelength Grating Optical Fiber Coupler

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Solution Overview

Problem

Existing optical fiber couplers require large and expensive lenses to efficiently couple light into and out of optical fibers, which limits their cost-effectiveness and miniaturization potential.

Innovation Solution

The use of a non-periodic, sub-wavelength grating layer between resonant cavities to control the phase front of light, allowing for efficient coupling and decoupling of light from optical fibers without the need for bulky lenses, by configuring the grating pattern to apply specific phase changes and shape the wavefront of light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a lens is used to couple light into and out of optical fibers, then coupling efficiency is improved, but the size and cost of the coupler increases

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidsize of coupler

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent replaces the traditional lens-based optical system with a sub-wavelength grating structure that uses diffraction and resonance effects to control light. The grating structure manipulates light waves through periodic variations in refractive index at sub-wavelength scales, eliminating the need for bulky lens components while achieving comparable or superior coupling efficiency.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental parameters of light control by transitioning from macroscopic lens curvature to sub-wavelength grating periods. The grating structure uses periods smaller than the wavelength of light to achieve effective light manipulation through diffraction and resonance, fundamentally changing how optical focusing is achieved.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a lens is used to couple light into and out of optical fibers, then coupling efficiency is improved, but the cost of the coupler increases

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidcost of coupler

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive lens components with a planar grating structure that can be fabricated using standard semiconductor manufacturing techniques. The sub-wavelength grating is formed by patterning a thin film layer with periodic structures, eliminating the need for precision optical machining and assembly required for lenses.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs a thin-film grating structure that can be mass-produced using inexpensive photolithography and deposition processes. The grating is formed as a planar pattern in a thin film layer, which is significantly cheaper to manufacture than precision optical lenses, enabling cost-effective production of optical fiber couplers.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If a lens is used to couple light into optical fibers, then coupling efficiency is improved, but the complexity of the coupler increases

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidcomplexity of coupler

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex multi-element lens system with a single planar grating structure. The grating is formed as a two-dimensional pattern in a thin film, eliminating the need for three-dimensional lens mounting mechanisms, alignment systems, and housing structures required for lens-based couplers.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the lens component entirely from the coupler design. By using sub-wavelength gratings to achieve light focusing and coupling directly at the fiber interface, the invention removes the need for separate lens elements, reducing both structural complexity and the number of alignment-critical components.

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 reduces the size and cost of optical fiber couplers while maintaining high coupling efficiency, enabling more compact and affordable optical communication systems.

Implementation Method 1

The sub-wavelength grating is configured to control the shape of the phase front of the light transmitted into and/or out of the optical fiber

Methodology Applied

Scientific EffectPhase modulation: Phase Modulation

Implementation Method 2

a non-periodic, sub-wavelength grating layer between resonant cavities to control the phase front of light

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 3

a non-periodic, sub-wavelength grating layer between resonant cavities

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS8265435B2Optical fiber coupling systems and methods for fabricating the same

Publication Date: 2012.09.11 HEWLETT PACKARD ENTERPRISE DEV LP

AI summary

Various embodiments of the present invention are directed to optical fiber coupling systems and to methods for fabricating optical fiber coupling systems. In one aspect, an optical fiber coupling system includes a first resonant cavity abutting the end of an optical fiber. The optical fiber coupling system includes a second resonant cavity located adjacent to the first cavity. The first and second resonant cavities are separated by a sub-wavelength grating layer configured with a non-periodic sub-wavelength grating. The optical fiber coupling system selectively couples light into and/or out of the optical fiber core.