Wafer-Bonded Microlens SiPh Interposer Alignment
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Solution Overview
Problem
Existing silicon photonic interposer assemblies face challenges in achieving precise alignment and signal integrity when coupling optical signals between silicon photonic devices and fiber optic connectors, leading to complex assembly processes and reduced performance.
Innovation Solution
The development of a solder reflowable silicon photonic interposer assembly with microlenses and optical connector mating features, utilizing grating couplers and MEMS fabrication techniques to align and focus optical signals, eliminating the need for active alignment of multiple optical elements and simplifying the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If active alignment of multiple optical elements is used, then alignment precision is improved, but assembly complexity increases
Solution Approach 1:
The microlenses are pre-formed on the wafer during the wafer bonding process before final assembly. This preliminary formation of optical elements eliminates the need for subsequent active alignment steps, as the lenses are already positioned with high precision relative to the grating couplers and fiber optic connectors during the wafer-scale bonding process
Solution Approach 2:
The patent combines multiple optical elements (microlenses, grating couplers, and fiber optic connectors) into a single integrated wafer structure through wafer-scale bonding. By merging these elements into one bonded assembly, the system eliminates the need for separate alignment operations that would be required if these components were assembled individually, thus reducing assembly complexity while maintaining alignment precision
2Manufacturing precision
If wafer scale bonding is used, then manufacturing precision is improved, but manufacturing process complexity increases
Solution Approach 1:
The wafer-scale bonding process is designed to be self-aligning, where the microlenses, grating couplers, and fiber optic connectors automatically achieve precise relative positioning through the bonding process itself. The process leverages the inherent precision of wafer-scale fabrication and bonding techniques to self-correct and self-align components without requiring external active alignment equipment or procedures
Solution Approach 2:
The wafer-scale bonding process serves multiple functions simultaneously: it bonds the wafer to the substrate, positions and aligns the microlenses, positions and aligns the grating couplers, and positions and aligns the fiber optic connectors. This multi-functional approach consolidates what would otherwise require multiple separate manufacturing steps into a single process, reducing overall process complexity despite the advanced bonding techniques required
3Reliability
If microlenses are integrated on wafer, then signal integrity is improved, but device complexity increases
Solution Approach 1:
The microlenses serve as intermediary optical elements between the grating couplers and the fiber optic connectors. These lenses mediate the optical coupling by collecting light from the grating couplers and focusing it onto the fiber connectors, thereby improving signal integrity. The microlenses act as a bridging element that simplifies the optical interface between components with different optical characteristics
Solution Approach 2:
The integration of microlenses on the wafer surface adds a new optical dimension to the device architecture. Rather than relying solely on planar grating coupler-to-fiber connections, the three-dimensional microlens structures provide additional optical path control and focusing capability, improving signal coupling efficiency and integrity while maintaining a compact integrated form factor
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
This solution enables high-precision alignment and improved signal integrity, reducing assembly complexity and time while enhancing performance by leveraging microlenses and grating couplers to collimate and focus optical signals, thus optimizing the coupling between silicon photonic devices and fiber optic connectors.
Implementation Method 1
The microlenses of the wafer serve to collimate and focus the optical signals exiting and entering the grating couplers and couples the signals to expanded beam fiber optic connectors
Implementation Method 2
Optical signals entering or exiting the SiPh interposer are coupled to the wafer using grating couplers
Data Source
AI summary
A silicon photonic (SiPh) packaging assembly includes a SiPh interposer and a wafer. The SiPh interposer has one or more optical gratings disposed thereon to couple an optical signal traversing the wafer. The wafer is bonded to the interposer, with the wafer including one or more microlenses, each microlens aligned with a respective optical grating and designed to direct the optical signal traversing the wafer at a desired angle.