Offset Photonic Chip Assembly for Alignment-Tolerant Coupling
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Solution Overview
Problem
Existing optical coupling devices between photonic chips are not robust enough to handle alignment errors typically observed during chip placement, particularly in the direction perpendicular to the optical signal propagation, and often require complex components like lenses and mirrors.
Innovation Solution
A simplified optical coupling device is designed with evanescent coupling zones and phase adaptation zones that utilize waveguides with specific geometric configurations to tolerate alignment errors, ensuring efficient energy transfer despite misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical coupling devices are used to achieve robust coupling against alignment errors, then coupling reliability is improved, but device complexity increases due to requiring many optical components such as lenses and mirrors
Solution Approach 1:
The patent extracts and eliminates the need for complex optical components (lenses, mirrors) from the coupling device. Instead, it uses a simplified waveguide-based evanescent coupling structure that achieves alignment error tolerance without these additional components, directly resolving the contradiction between reliability and complexity
Solution Approach 2:
The patent replaces the mechanical/optical system involving multiple discrete components (lenses, mirrors) with a integrated photonic system using waveguides and evanescent coupling. This substitution maintains coupling robustness while dramatically reducing device complexity
2Manufacturing precision
If alignment precision is improved to reduce errors, then coupling accuracy is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent designs the waveguide coupling structure with inherent tolerance to alignment errors. The evanescent coupling mechanism and waveguide geometry are configured to cushion against the expected ±3 μm placement errors, allowing standard placement tools to be used without requiring higher precision equipment
3Device complexity
If the optical coupling device is made simpler, then device complexity is reduced, but coupling reliability against alignment errors deteriorates
Solution Approach 1:
The patent changes key parameters of the waveguide structure (dimensions, spacing, material properties) to optimize evanescent coupling. By carefully controlling the waveguide separation distance and geometric parameters, the system achieves both simplicity and robustness simultaneously - the waveguides are positioned and dimensioned to maintain efficient coupling despite alignment variations
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 coupling device maintains high energy transmission rates (>50%) despite alignment errors, reducing complexity and cost by eliminating the need for additional optical components.
Implementation Method 1
The guide 40 and the guides 60 are shaped to transfer, by evanescent coupling, most of the energy of an optical signal propagating in the guide 40 to the guides 60
Data Source
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AI summary
An assembly comprising: - a first waveguide (40) fabricated in a first photonic chip and extending in a first direction to guide an optical signal at a wavelength λ, - an array (42) of several second waveguides (60) fabricated in a second photonic chip mounted on the first photonic chip, and - a power summing junction (34) having inputs optically connected to one end of each of the second waveguides (60). Each of the second waveguides has upstream (74, 80) and downstream (76, 82) portions offset from each other in the second direction. The conformations of the first waveguide and the second waveguides (60) are such that, for any position of the first waveguide above the array (42), the distance between one of the portions of the first waveguide and one of the portions of one of the second waveguides is less than λ/2.