Bonded Filter Substrates for WDM Yield
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Solution Overview
Problem
The low aggregate yield of monolithic filter arrays with multiple different optical filters in WDM systems makes it impractical to manufacture them at a reasonable cost, due to the low yield of each fabricated filter meeting specifications, which decreases as the number of different filters formed on a substrate increases.
Innovation Solution
The solution involves fabricating wavelength-selective filters on two substrates with different filters on each surface and bonding them together, with techniques such as matching thermal expansion coefficients and using absorbing bonding materials to minimize crosstalk and optimize filter positioning, allowing for higher yield by limiting the number of filters on each substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple different optical filters are formed on a single substrate to create monolithic filter arrays, then the system complexity is reduced, but the aggregate yield decreases as the number of different filters increases
Solution Approach 1:
The patent divides the filter array fabrication into multiple substrates, with each substrate containing a limited number of different filter types. This segmentation allows each substrate to be manufactured with high yield, and the complete filter array is assembled by bonding multiple substrates together, thus resolving the contradiction between system complexity and aggregate yield.
Solution Approach 2:
The patent combines multiple substrates, each containing different filter types, into a single integrated filter array through substrate bonding. This merging approach maintains the benefits of having multiple filter types while preserving the high yield of individual substrate manufacturing, effectively resolving the technical contradiction.
2Device complexity
If the number of different filters on each substrate is increased, then fewer substrates are needed, but the yield of each fabricated filter meeting specifications decreases
Solution Approach 1:
The patent segments the filter array into multiple substrates, each containing a limited set of filter types that can be manufactured with high precision and yield. This segmentation strategy allows each substrate to meet manufacturing specifications while the complete system achieves the desired filter diversity through substrate assembly.
3Productivity
If substrates are bonded together to create filter arrays, then manufacturing cost-effectiveness improves through higher yield, but alignment precision and optical performance must be maintained
Solution Approach 1:
The patent incorporates alignment features and bonding structures during the substrate fabrication process, before the actual bonding occurs. This preliminary action ensures that when substrates are bonded together, proper alignment is achieved, maintaining optical performance while enabling cost-effective manufacturing through high-yield substrate production.
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 approach increases the yield of filter arrays by ensuring that only good filters are bonded together, reducing optical power loss and making the manufacturing of filter arrays more cost-effective by improving the alignment and transmission efficiency of light beams.
Implementation Method 1
a bonding material bonds the first substrate to the second substrate
Implementation Method 2
using absorbing bonding materials to minimize crosstalk
Implementation Method 3
one or more first filters have been fabricated on a first surface of the first substrate, where the one or more first filters each transmit a first band of wavelengths
Data Source
AI summary
In the examples provided herein, an apparatus has a first substrate upon which one or more first filters have been fabricated on a first surface of the first substrate. The apparatus also has a second substrate upon which one or more second filters have been fabricated on a second surface of the second substrate, wherein the one or more first filters and the one or more second filters each transmit a different band of wavelengths. Additionally, the apparatus has a bonding material that bonds the first substrate to the second substrate.