Edge Coupler Fine Alignment by Heater-Induced Waveguide Bending
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Solution Overview
Problem
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 incorporating a dielectric layer with a cavity and an edge coupler featuring a waveguide core that extends over the cavity, with heaters positioned adjacent to the waveguide core to adjust its alignment through thermal expansion, allowing for precise alignment with a light source.
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 supported, but the ability to confine the incident mode deteriorates
Solution Approach 1:
The waveguide core is designed with an inverse taper geometry where the cross-sectional area dynamically varies along its length. The tip region has a reduced cross-sectional area to support mode transformation and size variation, while the base region has a larger cross-sectional area to confine the electromagnetic field. This dynamic geometric transition resolves the contradiction between mode adaptability and field confinement.
2Ease of operation
If the tip cross-sectional area is made small to facilitate coupling, then mode size variation is enabled, but alignment precision with light source deteriorates
Solution Approach 1:
The inverse taper provides a dynamic transition from a small tip area (good for coupling) to a larger base area (good for alignment). The gradual geometric change allows the waveguide to interface with small-mode light sources while maintaining stable alignment at the broader base region, resolving the contradiction between coupling ease and alignment precision.
3Adaptability or versatility
If the inverse taper tip area is reduced to support mode transformation, then mode conversion is facilitated, but light confinement deteriorates
Solution Approach 1:
The inverse taper creates a dynamic geometric profile where the cross-sectional area gradually increases from tip to base. This dynamic transition enables mode conversion at the small tip while the expanding geometry progressively confines the electromagnetic field, resolving the contradiction between mode conversion capability and light confinement.
4Object-generated harmful factors
If the waveguide core cross-sectional area is increased to confine light, then electromagnetic field confinement is improved, but mode transformation capability deteriorates
Solution Approach 1:
The inverse taper provides a dynamic geometric progression from small to large cross-sectional areas. The small tip region enables mode transformation capability while the progressively increasing area toward the base provides electromagnetic field confinement, resolving the contradiction between these two opposing requirements through spatial variation.
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 alignment mechanism enables effective mode transformation and improved light coupling by allowing the waveguide core to bend laterally, ensuring optimal alignment and increased light confinement, thereby enhancing the efficiency of light transfer.
Implementation Method 1
the first heater may be configured to expand in dimensions in response to being powered such that the portion of the waveguide core bends relative to a light output
Implementation Method 2
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
Data Source
Figure 1~2
Figure 2A~3A
Figure 4~5
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.