Angled Active Layer Vertical Optical Coupling Structure
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Solution Overview
Problem
Existing photonic integrated circuits face challenges in efficiently coupling light between non-semiconductor based waveguides and active semiconductor components, leading to high scattering losses due to sensitivity to fabrication tolerances.
Innovation Solution
A vertical coupling structure is introduced, featuring a waveguide core layer and an active layer where the guided mode is coupled. The active layer outside the coupling region is angled relative to the active layer in the coupling region, gradually increasing the distance between the waveguide core and the active layer away from the coupling region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lateral tapering or heterogeneous die bonding is used for coupling, then coupling between waveguides and active components is achieved, but scattering losses increase due to sensitivity to fabrication tolerances
Solution Approach 1:
The patent transitions from lateral coupling (in-plane) to vertical coupling (out-of-plane) by positioning the active layer above the waveguide core layer. This dimensional change allows the guided mode to couple to the active layer through the vertical direction, reducing sensitivity to fabrication tolerances and minimizing scattering losses while maintaining effective coupling efficiency.
2Reliability
If the active layer is positioned close to the waveguide core layer for strong coupling, then coupling efficiency improves, but fabrication tolerance sensitivity increases
Solution Approach 1:
By moving to vertical coupling, the patent decouples the sensitivity to lateral position variations from the coupling efficiency. The vertical positioning allows for robust coupling even with fabrication tolerances, as the coupling mechanism does not rely on precise lateral alignment.
Solution Approach 2:
The patent utilizes evanescent coupling through the coupling layer, where the coupling strength is controlled by the vertical distance and coupling layer properties rather than lateral positioning. This parameter change allows for tolerance-insensitive coupling while maintaining efficient energy transfer.
3Loss of energy
If the active layer is angled away from the coupling region, then scattering losses are minimized, but coupling strength may be reduced
Solution Approach 1:
The vertical coupling geometry allows the active layer to be angled or positioned optimally for minimizing scattering losses while maintaining strong coupling. The vertical dimension provides flexibility in positioning the active layer without compromising coupling strength, as the coupling occurs through the vertical evanescent field interaction rather than lateral overlap.
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 minimizes scattering losses and enhances optical coupling efficiency by optimizing the interaction between the waveguide core and the active layer, allowing for effective integration of non-semiconductor based waveguides with active semiconductor components.
Implementation Method 1
in the coupling region, a thickness of the coupling layer is such that the guided mode is evanescently coupled to the active layer
Data Source
AI summary
A coupling structure is presented, which comprises: a waveguide core layer supporting a guided mode and an active layer disposed above the waveguide core layer. In the coupling region, the guided mode is coupled to the active layer, and the active layer outside the coupling region is angled with respect to the active layer in the coupling region such that a distance between the waveguide core layer and the active layer gradually increases away from the coupling region.