Topology Optimized Waveguide for 2D TMD Phase Shifter
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Solution Overview
Problem
Integrated photonic phase shifters suffer from high optical losses and high-power requirements, and existing devices using thermo-optic elements or ionically doped semiconductors face issues with carrier injection losses and low refractive index changes, necessitating a more efficient phase shifting mechanism.
Innovation Solution
A photonic device employing a 2D transition metal dichalcogenide monolayer sheet over a topology optimized waveguide on a silicon-on-insulator substrate, where the waveguide is patterned to enhance mode overlap with the 2D TMD, allowing for a π phase shift with reduced length and lower power consumption by applying a controlled DC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 2D TMD is placed over a conventional waveguide, then phase shift is achieved, but the waveguide length must be many hundreds of microns which increases device size
Solution Approach 1:
The waveguide cross-section is locally modified in the region where the 2D TMD is positioned, creating a topology-optimized structure with enhanced mode confinement. This local structural change increases the modal overlap between the waveguide mode and the 2D TMD, thereby enhancing the phase shifting efficiency without requiring a longer waveguide.
2Ease of manufacture
If conventional waveguide structures are used with 2D TMD, then device fabrication is straightforward, but mode overlap is insufficient requiring long interaction lengths
Solution Approach 1:
The waveguide geometric parameters (width, height, and cross-sectional shape) are optimized in the region underneath the 2D TMD to maximize mode overlap. This topology optimization adjusts the waveguide parameters locally to enhance the electromagnetic field distribution, increasing the interaction efficiency between light and the 2D TMD material.
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 achieves a significant reduction in phase shifter length by about an order of magnitude, minimizing optical losses and enabling more compact integration of components, while maintaining efficient phase shifting with low power consumption.
Implementation Method 1
Via the Kerr effect, the 0 to π phase shift required for the phase shifting device is achievable.
Implementation Method 2
A change in the refractive index of the TMD is achieved by application of a DC voltage across the TMD.
Implementation Method 3
The topology optimized waveguide disperses the optical mode in the region of the 2D TMD. The increased overlap created by the topology optimized structure enhances the interaction between the optical mode and the TMD.
Data Source
AI summary
A silicon on insulator (SOI) photonic device having a waveguide is provided that includes a mode overlap portion with a topology optimized structure situated below an electrode of the capacitance structure. The device can significantly change a refractive index in a volume of mode overlap depending upon the applied potential to the capacitor and allows for a π phase shift in a modest mode overlap volume. The topology optimized structure has a waveguide and substrate that are partitioned in three dimensions using an extruded projection design. The electrode is a transition metal di-chalcogenide monolayer sheet (2D TMD). The enhanced mode overlay from the topology optimized waveguide portion allows a large reduction in the length of the waveguide with the mode overlap to achieve the needed phase shift for a photonic device.