Optical Fiber Grating-Coupler Connections with Low-Profile Mirrors
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Solution Overview
Problem
Existing methods for coupling optical fibers to photonic integrated circuits (PICs) face challenges in tolerance, manufacturability, cost, and complexity, particularly with grating couplers that require angled polished fibers and quartz fiber arrays, leading to increased production costs and package height.
Innovation Solution
A novel optical connector using a mirror to orient the optical fiber axis at small angles parallel to the PIC surface, integrated with a structured reflective surface and alignment groove, formed by precision stamping, allowing low-profile connections that match the mode field of existing grating couplers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grating couplers with angled polished fibers and quartz fiber arrays are used, then optical coupling functionality is achieved, but manufacturing cost and package height increase
Solution Approach 1:
The patent replaces expensive quartz fiber arrays with inexpensive plastic fiber arrays that can be manufactured through injection molding. The plastic ferrule assembly is designed as a disposable, low-cost component that achieves sufficient optical coupling functionality without requiring precision ground quartz materials, directly reducing manufacturing costs while maintaining adequate performance
Solution Approach 2:
The patent changes the orientation dimension of the fiber array by using a flat-polished configuration instead of angled polished fibers. This dimensional change allows the fiber end faces to be perpendicular to the fiber axis, enabling simpler manufacturing processes and reducing the need for complex angled polishing equipment and procedures
2Reliability
If grating couplers with angled polished fibers and quartz fiber arrays are used, then optical coupling functionality is achieved, but package height increases
Solution Approach 1:
The patent inverts the conventional approach by using flat-polished fiber end faces instead of angled polished surfaces. This inversion allows the fiber array to be positioned closer to the PIC surface, reducing the vertical distance light must travel and thereby decreasing package height while maintaining optical coupling effectiveness through the mirror's light redirecting function
3Manufacturing precision
If edge coupling method is used, then stringent alignment tolerances are required, but wafer-level testing is not possible
Solution Approach 1:
The patent introduces a mirror as an intermediary optical element that redirects light between the flat-polished fiber array and the grating coupler on the PIC. This intermediary component enables wafer-level testing by allowing optical access through the PIC surface without requiring edge access, thereby improving productivity while maintaining reasonable alignment tolerances through the mirror's light redirecting capability
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 solution provides improved tolerance, manufacturability, ease of use, and reduced costs while maintaining reliability and functionality, enabling low-profile connectors that fit into smaller transceiver packages.
Implementation Method 1
a mirror is provided to turn light to/from the optical fiber
Implementation Method 2
diffractive grating couplers
Data Source
AI summary
To couple light between an optical fiber and a grating coupler of a photonic integrated circuits, a mirror is provided to turn light to/from the optical fiber to allow the axis of the optical fiber to be oriented at small angles or parallel to the surface of the PIC, and lowered close to the surface of the PIC. The mirror is further configured to reshape light from a flat polished optical fiber to produce a mode field resembling the mode field of an angled polished optical fiber, to match the design angle of existing grating couplers that are designed to work with angled polished optical fibers. The mirror and optical fiber alignment structure in the optical connector are integrally/simultaneous formed by precision stamping.