Optical Waveguide Transition with Up-Tapered Section

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Solution Overview

Problem

Transition parts between optical waveguides with different index contrasts in monolithic, integrated optical circuits face challenges in minimizing losses and avoiding unwanted reflections, requiring precise control over loss differences.

Innovation Solution

A transition part comprising a non-adiabatically up-tapered longitudinal section followed by an adiabatically down-tapered section, with the transition arranged along the main direction of light propagation, to minimize optical losses and reduce reflections by keeping the transition area away from intense light fields.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a gradual narrowing or down-tapering of a lower layer is used to transition between waveguides, then the vertical mode confinement changes gradually, but this approach does not sufficiently minimize optical losses and unwanted reflections

Engineering Contradiction:

Improveoptical lossesVSAvoidtransition structure complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The transition part is divided into two distinct functional sections: an non-adiabatic up-tapered section for mode transformation and an adiabatic down-tapered section for gradual transition. This segmentation allows each section to perform its specific function optimally, minimizing overall optical losses while maintaining manufacturing feasibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The non-adiabatic up-tapered section performs a preliminary mode transformation before the light enters the transition area. By pre-adjusting the mode profile in the up-tapered section, the subsequent transition experiences reduced reflections and losses, effectively preparing the light field for the next stage.

Inventive Principle:

Principle #10Preliminary action

2Length of stationary object

If the transition area is placed close to intense light fields, then the transition can be compact, but this increases unwanted reflections and optical losses

Engineering Contradiction:

Improvetransition part lengthVSAvoidunwanted reflections

Core Design Contradiction:

Length of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The adiabatic down-tapered section acts as an intermediary between the intense light field region and the transition area. This intermediate section gradually transforms the mode profile, serving as a buffer that reduces abrupt changes and minimizes unwanted reflections while maintaining a compact overall structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If different waveguides are mixed in the same technical application, then functionality is enhanced, but achieving low-loss transitions between different index contrast waveguides becomes difficult

Engineering Contradiction:

Improvewaveguide mixing capabilityVSAvoidtransition losses

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

Different sections of the transition part have different structural properties tailored to specific functions: the up-tapered section has a specific geometry for mode transformation while the down-tapered section has different dimensions for gradual transition. This local differentiation allows optimal performance for transitioning between different index contrast waveguides while minimizing losses.

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 configuration effectively minimizes optical losses and reduces unwanted reflections by ensuring that the transition area is kept away from intense light field areas, allowing for precise control over loss differences between waveguides.

Implementation Method 1

the transition part comprises a non-adiabatically up-tapered longitudinal section, and in that the transition between the two waveguides is arranged after the up-tapered longitudinal section as seen along the main direction of propagation of the light

Methodology Applied

Scientific EffectAdiabatic mode transformation:

Implementation Method 2

The ability of a waveguide to limit the size of the light field perpendicularly to the longitudinal direction of the waveguide depends on its index contrast

Methodology Applied

Scientific EffectOptical waveguide confinement: Waveguide (optics)

Data Source

PatentUS8041164B2Transition device for optical waveguides

Publication Date: 2011.10.18 II VI DELAWARE INC

AI summary

A transition part (1) between two optical waveguides (2,3) with different index contrast is characterised in that the transition part (1) includes a non-adiabatically up-tapered longitudinal section (8), and in that the transition (7) between the two waveguides (2,3) is arranged after the up-tapered longitudinal section (8) as seen along the main direction (L) of propagation of the light. A method of manufacturing the transition part is also described.