Edge Coupler Fine Alignment With Thermal Overhang Adjustment
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Solution Overview
Problem
Existing edge couplers in photonics chips face challenges in fully confining the incident mode due to the small cross-sectional area at the tip of the inverse taper, leading to inefficient mode transformation and alignment issues with light sources.
Innovation Solution
A structure comprising a dielectric layer on a semiconductor substrate with an edge coupler featuring a waveguide core that extends past the edge of the dielectric layer and overhangs a cavity, accompanied by a heater positioned adjacent to the waveguide core to adjust its alignment through thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the cross-sectional area at the tip of the inverse taper is reduced to enable mode transformation, then mode size variation is achieved, but the ability to confine the incident mode deteriorates
Solution Approach 1:
The waveguide core extends in the vertical dimension by overhanging the cavity beneath the dielectric layer edge. This three-dimensional configuration allows the tip to have a small horizontal cross-section for mode transformation while the vertical extension provides additional confinement space for the electromagnetic field, resolving the contradiction between mode size variation and field confinement.
2Adaptability or versatility
If the tip cross-section is made small to facilitate mode conversion, then mode transformation is supported, but alignment precision with light sources deteriorates
Solution Approach 1:
By extending the waveguide core vertically over the cavity, the invention creates an adjustable alignment mechanism. The overhanging portion can be positioned with high precision relative to the light source, and the cavity provides space for alignment adjustment structures, improving alignment precision while maintaining the small horizontal tip size needed for mode conversion.
Solution Approach 2:
The cavity acts as an intermediary space between the light source and the waveguide core tip. This space allows for the insertion of alignment adjustment mechanisms and provides a buffer zone that facilitates precise alignment while keeping the coupling interface small for effective mode transformation.
3Productivity
If the waveguide core extends past the dielectric layer edge to improve coupling, then light transfer efficiency is improved, but structural complexity increases
Solution Approach 1:
The waveguide core is merged with the cavity structure, where the cavity serves dual purposes: providing mechanical support/alignment adjustment space and acting as part of the optical confinement structure. This integration reduces the need for separate alignment components, lowering structural complexity while maintaining improved light transfer efficiency through the extended core configuration.
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
The proposed solution enhances the confinement of the incident mode and improves alignment adjustments, thereby increasing the efficiency of light transfer and maintaining optimal alignment with light sources over time.
Implementation Method 1
a heater positioned adjacent to the waveguide core to adjust its alignment through thermal expansion
Data Source
AI summary
Structures including an edge coupler and methods of forming such structures. The structure comprises a dielectric layer on a semiconductor substrate. The dielectric layer includes a cavity and an edge defining a boundary of the cavity. The structure further comprises an edge coupler including a waveguide core. The waveguide core includes a portion that extends past the edge of the dielectric layer and overhangs the cavity. The structure further comprises a heater positioned adjacent to the portion of the waveguide core. The heater is spaced by a gap from the portion of the waveguide core.