Vertical Directional Coupler for Waveguide SEED Integration
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Solution Overview
Problem
The integration of waveguide self-electrooptic effect devices (SEEDs) with other waveguides faces challenges in low-loss light routing and scalability due to complex fabrication processes and increased absorptive losses, limiting the interconnection of complex optical logic circuits.
Innovation Solution
The integration of waveguide SEEDs with waveguide interconnects using vertical directional coupling, where the active waveguide layer forms a vertical directional coupler with the waveguide, allowing efficient light coupling and interaction, and the use of rib layers and trenches for lateral confinement to reduce reflections and losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If waveguide SEEDs are butt-coupled to passive waveguides using regrowth, then light routing between SEEDs is achieved, but fabrication complexity increases and yield decreases
Solution Approach 1:
The patent extracts the active SEED material from the waveguide region where passive interconnection is needed, creating a dedicated passive waveguide path. This separation allows the passive interconnect to be optimized for low-loss light routing without the complications of active material regrowth, thereby simplifying fabrication and improving yield while maintaining functionality.
2Ease of operation
If doping is used to electrically bias the SEED, then electrical control is achieved, but absorptive losses increase
Solution Approach 1:
The patent applies local quality by doping only the spacer layer regions where electrical biasing is needed, while keeping the passive interconnect waveguide regions undoped. This localized doping approach enables electrical control of the SEED devices without introducing absorptive losses in the passive light routing sections, thus resolving the contradiction between ease of operation and energy loss.
3Adaptability or versatility
If complex fabrication processes are used to integrate SEEDs with waveguides, then light routing functionality is achieved, but scalability is limited
Solution Approach 1:
The patent segments the waveguide structure into distinct functional regions: active SEED regions with doped spacers for electrical control, and passive interconnect regions with undoped spacers for low-loss light routing. This segmentation allows each region to be optimized independently and facilitates scalable fabrication processes, enabling the integration of large numbers of SEED devices without proportionally increasing fabrication complexity.
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 enables efficient coupling and low-loss transmission of light between SEEDs, facilitating the creation of compact, high-performance optical logic circuits with reduced complexity and increased scalability, while maintaining high-speed modulation and low optical scattering loss.
Implementation Method 1
The core of the passive waveguide is aligned with the waveguide portion of the waveguide SEED... the active waveguide layer in the SEED is positioned to form a vertical directional coupler with the waveguide
Data Source
AI summary
A self-electrooptic effect device (“SEED”) is integrated with waveguide interconnects through the use of vertical directional couplers. Light initially propagating in the interconnect waveguide is vertically coupled to the active waveguide layer of the SEED and, if the SEED is in the transparent state, the light is coupled back to the interconnect waveguide.