Waveguide Alignment via NIL Positioning Elements

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Solution Overview

Problem

Existing optical devices with stacked waveguides face challenges in precisely controlling the relative positioning of waveguides, which is essential for minimizing aberrations and unwanted optical effects, especially when using adhesives that can flow and affect the optical functionality.

Innovation Solution

The use of NanoImprint Lithography (NIL) positioning elements on the surfaces of waveguides allows for precise control of the relative position and spacing between waveguides, eliminating the need for complex optical feedback systems and preventing adhesive flow into optically functional areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If adhesives are used to attach stacked waveguides, then the waveguides can be bonded together, but the adhesive flow cannot be precisely controlled and may affect optical functionality

Engineering Contradiction:

Improvebonding reliabilityVSAvoidadhesive position control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The adhesive application area is segmented into multiple discrete zones using adhesive barriers. These barriers divide the bonding interface into controlled regions where adhesive is permitted to flow, preventing uncontrolled spreading while maintaining reliable bonding in specific areas.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Adhesive barriers act as intermediary structures between the waveguide surfaces and the adhesive. These barriers mediate the interaction by defining the boundaries of adhesive flow, controlling its spread while still allowing bonding to occur in the intended areas.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If waveguides are placed close together to reduce device volume, then the apparent volume is minimized, but evanescent wave coupling and crosstalk increase

Engineering Contradiction:

Improvedevice volumeVSAvoidevanescent wave coupling

Core Design Contradiction:

Volume of moving objectVSObject-generated harmful factors

Solution Approach 1:

The harmful evanescent wave coupling is extracted and isolated by introducing air gaps between the waveguides. These gaps act as barriers that prevent the harmful optical interactions while allowing the waveguides to be positioned close together for compact device volume.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If adhesives are applied to bond waveguides, then the waveguides are attached together, but lateral positioning precision is compromised due to adhesive flow

Engineering Contradiction:

Improvebonding strengthVSAvoidlateral positioning precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The bonding interface is segmented into discrete adhesive zones using barriers. This segmentation confines adhesive flow to specific lateral regions, preventing it from migrating into optically functional areas while maintaining strong bonding in the intended zones.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the waveguide surface are given different properties: some regions have adhesive barriers that prevent flow, while other regions have surfaces optimized for bonding. This local differentiation ensures precise lateral positioning while maintaining bonding strength where needed.

Inventive Principle:

Principle #3Local quality

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 enables accurate and stable positioning of waveguides, reducing aberrations and ensuring the optical device functions correctly, while also allowing for precise control of adhesive placement to prevent interference with optically functional regions.

Implementation Method 1

the first positioning element is a NanoImprint Lithography, NIL, structure

Methodology Applied

Scientific EffectNanoImprint Lithography:

Implementation Method 2

Stacked waveguides are generally attached to each other using an adhesive such as a glue

Methodology Applied

Scientific EffectAdhesive: Adhesive

Implementation Method 3

Light then propagates within each waveguide by total internal reflection

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS20250180832A1Optical device

Publication Date: 2025.06.05 SNAP INC

AI summary

Optical devices and methods include a first waveguide having a first surface and a second waveguide including a second surface. The first waveguide is at a fixed position relative to the second waveguide with the first surface at least partly facing the second surface, and the first surface includes a first positioning element. The first positioning element is a NanoImprint Lithography (NIL) structure. The optical device further includes an adhesive arranged for attaching the first surface to the second surface, where the first positioning element is arranged to control a position of the adhesive. The first positioning element includes a philic region adapted to attract the adhesive, or a phobic region adapted to repel the adhesive.