Photonic Crystal Waveguide Anti-Coupling Substrate
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Solution Overview
Problem
Electronic-photonic devices face optical loss due to evanescent coupling between the inner core and the substrate, which disrupts the propagation of optical signals, particularly in integrated circuits where materials with similar refractive indices can couple and attract optical signals away from the waveguide.
Innovation Solution
A photonic device is designed with an anti-coupling area in the substrate that extends below the inner core and cladding layer, featuring a plurality of holes to reduce coupling, and can also function as a photonic crystal with a customizable photonic bandgap, using materials with refractive indices equal to or less than the outer cladding material to minimize optical leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If materials with refractive index matching the inner core are used in the substrate, then manufacturing is simplified, but optical coupling loss increases due to evanescent coupling
Solution Approach 1:
The patent introduces an anti-coupling layer as an intermediary between the substrate and the waveguide core. This layer has a refractive index lower than both the substrate and the core, acting as a buffer that prevents direct evanescent coupling while allowing the substrate to maintain its simple, low-cost material composition.
Solution Approach 2:
The patent applies a specific material property (low refractive index) locally at the interface between substrate and waveguide, rather than requiring the entire substrate to have special properties. This localized approach maintains ease of manufacture for the bulk substrate while addressing optical coupling only where needed.
2Device complexity
If the waveguide structure is simplified without additional anti-coupling structures, then device complexity is reduced, but optical propagation reliability deteriorates due to coupling loss
Solution Approach 1:
The anti-coupling layer serves as a mediator that decouples the optical fields between substrate and core, preventing signal loss without requiring complex active control mechanisms or additional optical components.
Solution Approach 2:
The patent modifies the refractive index parameter of the layer adjacent to the substrate, creating a gradient or step change that optimizes optical confinement. This parameter change is achieved through material selection rather than structural complexity.
3Adaptability or versatility
If a photonic crystal structure with periodic holes is implemented, then photonic bandgap functionality is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The photonic crystal structure divides the waveguide core into periodic segments with holes, creating a segmented pattern that produces the photonic bandgap effect through constructive and destructive interference of light waves.
Solution Approach 2:
The patent achieves photonic bandgap functionality by changing the geometric parameters (hole size, spacing, pattern) rather than requiring complex material compositions or additional processing steps, allowing optimization within standard manufacturing capabilities.
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 anti-coupling area effectively mitigates optical coupling between the inner core and the substrate, reducing potential propagation loss and allowing unencumbered electromagnetic wave propagation, while the photonic crystal functionality provides a customizable bandgap for enhanced performance and efficiency in electronic-photonic devices.
Implementation Method 1
optical loss due to evanescent coupling between the inner core and the substrate
Implementation Method 2
photonic crystals can provide a photonic bandgap for electromagnetic waves, where the presence of particular wavelengths is blocked
Implementation Method 3
Wave guiding occurs upon internal reflection of electromagnetic waves at the interface between the higher refractive index inner core and the lower refractive index outer cladding material
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A photonic device and methods of formation that provide an area providing reduced optical coupling between a substrate and an inner core of the photonic device are described. The area is formed using holes in the inner core and an outer cladding. The holes may be filled with materials which provide a photonic crystal. Thus, the photonic device may function as a waveguide and as a photonic crystal.