Low-Stress Dielectric Waveguide Subassembly for Optical Interconnects
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Solution Overview
Problem
Current optoelectronic packaging technologies face challenges in fabricating planar waveguide structures with low stress and low optical loss, which are essential for compact and economical interposers and sub mount assemblies in optical communication systems, as existing methods struggle to achieve sufficient thickness and reduce signal attenuation.
Innovation Solution
The development of a dielectric waveguide structure integrated into a substrate, using a stack of silicon oxynitride films deposited at low temperatures, with a buffer layer and spacer layers to minimize stress and optical loss, allowing for the formation of thick waveguides with low optical loss and low stress, enabling efficient optical signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If planar waveguide structures are fabricated with sufficient thickness to reduce optical loss, then optical transmission quality improves, but manufacturing difficulty increases due to stress control limitations
Solution Approach 1:
The patent employs a composite dielectric stack structure consisting of alternating high-index and low-index dielectric layers. This composite material approach enables the waveguide to achieve sufficient thickness for low optical loss while the alternating refractive indices provide stress distribution that prevents cracking and delamination, thereby resolving the manufacturing difficulty associated with thick single-material waveguides.
Solution Approach 2:
The patent systematically varies multiple parameters including dielectric material composition, layer thickness ratios, and refractive index differences to optimize both optical performance and mechanical stress characteristics. By changing these parameters, the waveguide achieves the desired thickness for low optical loss while maintaining stress levels within acceptable manufacturing limits.
2Adaptability or versatility
If free space transmission is used for optical signals, then component flexibility is maintained, but package size increases and signal loss increases due to scattering and reflection
Solution Approach 1:
The patent merges the optical waveguide function directly into the substrate structure, eliminating the need for separate discrete optical components and free space transmission paths. This integration reduces package size by combining multiple functions into a single planar structure while maintaining component flexibility through the modular nature of the dielectric stack design.
3Ease of operation
If free space transmission with lenses is used, then optical signal routing is achieved, but package size increases due to spatial volume requirements
Solution Approach 1:
The patent transitions from three-dimensional free space optical paths requiring lenses to a two-dimensional planar waveguide structure. By confining optical signals to propagate within the planar dielectric stack, the system eliminates the spatial volume requirements for lenses and complex routing mechanisms, achieving compact integration while maintaining optical signal routing capability through the planar geometry.
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 results in planar dielectric waveguides with optical losses less than 1 dB/cm and stress levels below 20 MPa, facilitating the creation of compact, low-loss, and economically manufacturable optoelectronic packages for optical communication systems.
Implementation Method 1
Optical dielectric interposers are formed from the integration and patterning of this planar waveguide structure with a substrate to form compact interposers and optical sub mount assemblies that provide low loss in optoelectronic packages that are used for optical signal routing and transmission
Implementation Method 2
a stack of silicon oxynitride films deposited at low temperatures
Data Source
AI summary
An optical subassembly includes a planar dielectric waveguide structure that is deposited at temperatures below 400 C. The waveguide provides low film stress and low optical signal loss. Optical and electrical devices mounted onto the subassembly are aligned to planar optical waveguides using alignment marks and stops. Optical signals are delivered to the submount assembly via optical fibers. The dielectric stack structure used to fabricate the waveguide provides cavity walls that produce a cavity, within which optical, optoelectronic, and electronic devices can be mounted. The dielectric stack is deposited on an interconnect layer on a substrate, and the intermetal dielectric can contain thermally conductive dielectric layers to provide pathways for heat dissipation from heat generating optoelectronic devices such as lasers.