Passive Alignment of Optical Filters and Mirrors in Sub-Mount Cavities
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Solution Overview
Problem
The high cost and complexity of actively aligning optical components in Receiver Optical Sub-Assemblies (ROSA) and Transmitter Optical Sub-Assemblies (TOSA) due to the need for precise wavelength separation and combination, which increases manufacturing time and expense.
Innovation Solution
The use of pre-fabricated cavities on a substrate for passive alignment of optical filters and mirrors, eliminating the need for active tuning by ensuring precise alignment through the design of the sub-mount and substrate features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If active alignment is used to align optical filters and mirrors with high precision, then optical alignment accuracy is improved, but manufacturing cost and assembly time increase
Solution Approach 1:
The patent applies preliminary action by pre-fabricating alignment features (cavities, grooves, protrusions) on the substrate before assembling the optical components. These features are created during the substrate fabrication process, ensuring that when optical filters and mirrors are placed into the cavities and grooves, they are automatically aligned to the correct positions and orientations without requiring subsequent active alignment adjustments.
Solution Approach 2:
The patent implements self-service through self-aligning mechanical structures where the optical components themselves interact with the pre-fabricated features to achieve automatic alignment. The mirrors and optical filters have engagement features that fit into corresponding cavities and grooves, causing them to self-align to precise positions and orientations without external adjustment mechanisms or active tuning during assembly.
2Manufacturing precision
If active alignment with manual adjustment is used, then optical component alignment precision is improved, but assembly time increases
Solution Approach 1:
The alignment features are prepared in advance during substrate fabrication, eliminating the need for time-consuming manual alignment operations during assembly. The cavities, grooves, and protrusions are precisely formed beforehand to guide and position the optical components automatically when they are placed into the assembly.
Solution Approach 2:
The optical components automatically align themselves through mechanical engagement with the pre-fabricated features. The mirrors and optical filters have engagement features that fit into corresponding cavities and grooves, causing them to self-align to precise positions and orientations without requiring manual adjustment or external intervention during the assembly process.
3Ease of manufacture
If pre-fabricated cavities are used for passive alignment, then manufacturing cost is reduced, but alignment precision may be compromised
Solution Approach 1:
The alignment system is segmented into multiple independent features: cavities for positioning mirrors, grooves for positioning optical filters, and protrusions for mechanical engagement. Each feature is optimized for its specific function, allowing the substrate to provide precise alignment for multiple different optical components simultaneously through the same fabrication process.
Solution Approach 2:
The patent uses three-dimensional cavity and groove structures that constrain optical components in multiple spatial dimensions simultaneously. The cavities and grooves provide depth, width, and orientation constraints, transforming a two-dimensional positioning problem into a three-dimensional solution that achieves high precision through vertical engagement as well as horizontal positioning.
Data Source
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AI summary
Embodiments described herein describe a sub-mount that is etched to include respective cavities with at least two adjacent sides that align optical filters and a mirror. Moreover, the cavities are arranged on the sub-mount such that when the filters and mirror are disposed in the cavities, they align in a manner that enables the performance of a multiplexing or demultiplexing function as part of, for example, a zigzag multiplexer/demultiplexer. In one embodiment, the filters and mirrors are aligned passively rather than actively. The sub-mount may then be placed on a substrate that includes other components of a ROSA or TOSA. In one embodiment, the substrate is also etched to include a cavity two adjacent sides to align the sub-mount so that sub-mount is passively aligned once disposed into the cavity.