Mechanical Waveguide-PIC Alignment for Lower Optical Coupling Loss
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Solution Overview
Problem
Existing optical coupling systems between glass substrates and silicon-based photonic integrated circuits suffer from undesirable coupling losses due to dimensional variations in passive mechanical mating features, leading to misalignments that affect optical signal transfer efficiency.
Innovation Solution
Implementing a dual alignment scheme with separate sets of mechanical alignment features for vertical and lateral alignment, using standoff features and alignment protrusions on an optical interposer to align with recesses in a PIC die, allowing for improved registration of waveguides and reducing misalignment sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If passive mechanical mating features are used for alignment, then mechanical registration is achieved, but dimensional variations cause misalignment and coupling loss
Solution Approach 1:
The alignment system is segmented into two independent sets of features: one set for vertical alignment (standoff features) and another set for lateral alignment (alignment protrusions and grooves). This segmentation allows each set to optimize for its specific function without being constrained by the other, thereby improving overall alignment accuracy and reducing coupling loss despite manufacturing variations.
Solution Approach 2:
The optical interposer acts as an intermediary component between the glass substrate and the PIC die. It incorporates both vertical standoff features and lateral alignment protrusions, mediating the alignment process by translating vertical positioning into lateral registration, thus compensating for dimensional variations in either component.
2Reliability
If tight tolerances are required for alignment features, then coupling loss is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
By dividing alignment into separate vertical and lateral functions with dedicated features, each feature set can use relaxed tolerances appropriate for its specific purpose, rather than requiring all features to meet tight universal tolerances. The vertical standoff features handle height compensation while lateral protrusions handle position registration.
Solution Approach 2:
The invention changes the alignment approach from relying on precise dimensional control of single features to using a combination of features with different functional parameters. Vertical features control height with relaxed lateral tolerances, while lateral features control position with relaxed vertical tolerances, overall improving manufacturability.
3Device complexity
If single set of alignment features is used, then device complexity is reduced, but misalignment sensitivity increases
Solution Approach 1:
The alignment system is divided into two independent functional sets: vertical standoff features and lateral alignment protrusions. This segmentation reduces sensitivity to misalignment by allowing each set to independently compensate for errors in its respective dimension, improving overall alignment accuracy.
Solution Approach 2:
The invention addresses alignment in multiple dimensions by introducing standoff features that operate in the vertical dimension while alignment protrusions operate in the lateral dimension. This multi-dimensional approach decouples the alignment problems, reducing sensitivity to misalignment in either dimension.
Data Source
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AI summary
An apparatus includes an optical interposer including a first surface, a first mating protrusion extending outwardly from the first surface, and two or more alignment protrusions extending outwardly from the first surface. The first mating protrusion is to be partially disposed within a first recess formed in a second surface of a photonic integrated circuit (PIC) die when the first surface of the optical interposer opposes the second surface of the PIC die and respective distal surfaces of the two or more alignment protrusions contact the second surface of the PIC die. A first portion of an outer surface of the first mating protrusion is to contact a first side wall of the first recess and a second portion of the outer surface of the first mating protrusion is to oppose a second side wall of the first recess such that a second space is to be defined therebetween.