Optical Integrated Circuit With Open-Cavity Collimation for Precise Alignment
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Solution Overview
Problem
Existing optical isolators in bulk form are cumbersome to fabricate and assemble, leading to issues with scalability, accuracy, and cost due to the need for hand-polished GRIN lenses and complex alignment processes.
Innovation Solution
An optical integrated circuit design that incorporates collimating elements and optical waveguides directly into a substrate with open cavities, allowing for improved alignment and scalability, and reducing costs by eliminating the need for manual assembly and alignment of separate components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bulk optical isolators with hand-polished GRIN lenses are used, then optical isolation function is achieved, but manufacturing complexity and assembly time increase significantly
Solution Approach 1:
The patent merges the GRIN lenses and optical isolator into a single integrated optical component fabricated on a common substrate. The collimating lenses are formed directly on the substrate alongside the waveguides and isolator, eliminating the need for separate manual assembly of multiple components. This integration directly reduces assembly complexity while maintaining the optical isolation function.
Solution Approach 2:
The optical circuit is segmented into distinct functional regions on the substrate, with each component (waveguides, collimating lenses, optical isolator) fabricated in its designated area. This segmentation allows for systematic fabrication and reduces the complexity of integrating multiple separate bulk components.
2Reliability
If hand-polished GRIN lenses are used for bulk optical isolators, then optical collimation is achieved, but production cost and time increase
Solution Approach 1:
The patent replaces the mechanical hand-polishing process with a photolithographic fabrication process. The collimating lenses are formed using standard semiconductor manufacturing techniques including photoresist coating, patterning, and etching, which are automated and suitable for high-volume production. This substitution eliminates manual labor while maintaining optical collimation quality.
Solution Approach 2:
The fabrication process parameters are optimized to achieve the desired lens profiles and optical properties through controlled photolithographic exposure and etching conditions. By adjusting parameters such as photoresist thickness, exposure energy, and etch depth, the collimation performance is achieved through a scalable manufacturing process rather than manual polishing.
3Reliability
If separate bulk components are assembled manually, then optical isolation is achieved, but alignment precision and scalability are limited
Solution Approach 1:
By merging all optical components into a single integrated circuit on one substrate, the alignment precision problem is fundamentally solved. The waveguides, collimating lenses, and optical isolator are all fabricated in predetermined positions relative to each other using photolithographic patterning, ensuring precise alignment without manual intervention. This integration maintains optical isolation performance while achieving superior alignment precision.
Solution Approach 2:
The alignment is predetermined during the fabrication process itself, before the actual optical assembly. The photolithographic patterns define the exact positions of all components, and the subsequent fabrication steps automatically maintain these relative positions. This preliminary positioning action eliminates the need for post-fabrication alignment adjustments.
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 integrated circuit design enhances scalability, reduces production costs, and improves alignment precision, enabling more efficient and cost-effective fabrication of optical isolators and other optical components.
Implementation Method 1
a first collimating element for each set, the first collimating element of a set being arranged in the open cavity of that set at or near the first end facet of the first optical waveguide of that set to collimate light from that first optical waveguide
Data Source
AI summary
An optical integrated circuit includes a substrate, at least one open cavity provided in said substrate, at least one set of optical waveguides for each open cavity, each set including a first optical waveguide and a second optical waveguide. The first and second optical waveguides are arranged in the substrate and include a first end facet ending in the open cavity of that set, and a first collimating element for each set. The first collimating element is arranged in the open cavity at or near the first end facet of the first optical waveguide to collimate light from that waveguide. A second collimating element for each set is arranged in the open cavity at or near the first end facet of the second optical waveguide to collimate light into that waveguide. A method for fabricating the same.