Taper-Based Spot-Size Converter With Optical Buffering Layer

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Solution Overview

Problem

Existing optical data communication systems face challenges in efficiently coupling light from external optical fibers to on-chip optical waveguides due to significant dimensional mismatch, leading to loss mechanisms and sensitivity to refractive index variations.

Innovation Solution

The use of taper-based spot-size converters with optical buffering layers and intermediate optical mode converters to guide and convert optical modes, reducing the footprint and non-linear losses, and enhancing robustness against fabrication variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If taper-based spot-size converters are used to couple light from external optical fibers to on-chip optical waveguides, then coupling efficiency is improved, but sensitivity to refractive index variations and fabrication errors increases

Engineering Contradiction:

Improvecoupling efficiencyVSAvoidsensitivity to refractive index variations

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent introduces an intermediate optical buffering layer with refractive index n_buffering between the cladding material (n_cladding) and the optical waveguide (n_waveguide). This buffering layer acts as a mediator that decouples the optical mode from direct interaction with the substrate and handle, thereby reducing sensitivity to refractive index variations and fabrication errors while maintaining improved coupling efficiency through the taper structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If taper-based spot-size converters are used to reduce dimensional mismatch, then fiber-to-chip optical coupling efficiency is improved, but device footprint increases

Engineering Contradiction:

Improveoptical coupling efficiencyVSAvoiddevice footprint

Core Design Contradiction:

ProductivityVSArea of stationary object

Solution Approach 1:

The patent employs a vertical buffering layer structure that utilizes the vertical dimension (z-axis) to provide optical buffering and mode control. By positioning the buffering layer at a controlled distance above the optical waveguide, the design achieves improved coupling efficiency through enhanced mode overlap while minimizing the horizontal footprint of the device.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If optical buffering layer is positioned at controlled distance from optical waveguide, then robustness against fabrication variations is enhanced, but insertion loss increases

Engineering Contradiction:

Improverobustness against fabrication variationsVSAvoidinsertion loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent optimizes the vertical position (distance) of the optical buffering layer relative to the optical waveguide to achieve a balance between robustness and insertion loss. By carefully controlling the buffering layer's distance from the waveguide, the design enhances tolerance to fabrication variations while minimizing optical power loss through optimized evanescent field coupling.

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 approach improves the efficiency of fiber-to-chip optical coupling, reduces insertion loss, and enhances the reliability and performance of optical communication systems by buffering against refractive index variations and minimizing the impact of fabrication errors.

Implementation Method 1

An index of refraction of the optical buffering layer is greater than an index of refraction of the cladding material. The optical buffering layer is positioned a distance away from a top surface of the optical waveguide so as to guide an input optical mode at controlled vertical level relative to the optical waveguide

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

The optical buffering layer is positioned a distance away from a top surface of the optical waveguide so as to buffer against refractive index variations

Methodology Applied

Scientific EffectRefractive index buffering: Refraction

Data Source

PatentUS12313882B2Taper-based spot-size converter implementing intermediate optical mode converter

Publication Date: 2025.05.27 AYAR LABS INC

AI summary

An optical coupling device includes an optical waveguide disposed on a substrate. An index of refraction of the optical waveguide is greater than an index of refraction of the substrate. The optical coupling device includes a cladding material disposed alongside and above the optical waveguide. An index of refraction of the cladding material is less than the index of refraction of the optical waveguide. The optical coupling device includes an optical buffering layer disposed within the cladding material above the optical waveguide. The optical buffering layer has an index of refraction greater than the index of refraction of the cladding material. The optical buffering layer is positioned a distance away from a top surface of the optical waveguide so as to guide an input optical mode at controlled vertical level relative to the optical waveguide, with the input optical mode overlapping the optical waveguide.