Sub-wavelength Periodic Regions for Visible Light Waveguide Integration
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Solution Overview
Problem
Existing optical waveguide technologies face challenges in guiding light in the visible wavelength range due to absorption characteristics of crystalline semiconductors like Si, GaAs, or InP, and photonic crystals require high dielectric constant contrasts, limiting areal integration density and suitable materials for visible wavelengths.
Innovation Solution
A waveguide with sub-wavelength sized periodic regions embedded in a planar substrate, featuring two parallel periodic arrangements with specific dielectric constants, optimized through simulations of Maxwell's equations to minimize transverse loss and achieve total internal reflection, using materials like polymers or transparent oxides for reduced absorption and increased integration density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photonic crystal structures are used to guide light, then light confinement is achieved, but the structure extends considerably transverse to the guiding direction (4-5 lattice periods or more), which prevents the realization of relatively dense areal integration
Solution Approach 1:
The photonic crystal structure is segmented into isolated sub-wavelength sized regions arranged in periodic patterns, rather than using continuous lattice structures. This segmentation allows light confinement through the periodic dielectric modulation while reducing the transverse footprint to sub-wavelength dimensions, enabling dense areal integration.
Solution Approach 2:
The invention transitions from two-dimensional photonic crystal lattices to a structure where periodic sub-wavelength regions are embedded within a waveguide layer. This dimensional reconfiguration confines light primarily in the transverse direction through the periodic dielectric constant modulation, while allowing extended propagation along the waveguide, thereby reducing the transverse footprint.
2Area of stationary object
If crystalline semiconductors such as Si, GaAs or InP are used for the core material, then high dielectric constant contrast is achieved for high areal integration density, but they are not suitable for the visible wavelength range because of their absorption characteristics
Solution Approach 1:
The waveguide structure employs local quality variation through periodic sub-wavelength regions with high dielectric constant embedded in a lower dielectric constant waveguide layer. This local dielectric modulation provides sufficient light confinement without requiring high absorption-loss materials, enabling visible wavelength transmission while maintaining integration density.
Solution Approach 2:
The invention uses composite material structures combining waveguide layer material with periodic high-dielectric constant regions. This composite approach achieves the necessary dielectric contrast for light confinement using materials suitable for visible wavelengths, avoiding the absorption losses of pure crystalline semiconductors while maintaining integration density benefits.
3Reliability
If light is confined within a core material having relatively high dielectric constant surrounded by lower dielectric constant cladding, then light guidance is achieved, but the core material must have relatively low absorption in the wavelength range to be transmitted
Solution Approach 1:
Instead of relying on a continuous high-dielectric constant core, the invention uses periodic sub-wavelength regions with high dielectric constant embedded in the waveguide layer. This periodic dielectric modulation creates effective light guidance through photonic bandgap effects and total internal reflection, achieving reliable light guidance while using materials with lower absorption loss suitable for visible wavelengths.
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 allows for efficient light transmission with reduced loss, enabling the use of crystalline semiconductors in the visible range and facilitating denser areal integration, compatible with silicon photonics and polymer waveguide technology, while offering a smaller footprint compared to photonic crystal waveguides.
Implementation Method 1
optimized through simulations of Maxwell's equations to minimize transverse loss and achieve total internal reflection
Implementation Method 2
A transparent layer with a dielectric constant between the dielectric constant of the periodic arrangement and the dielectric constant of the substrate/cladding provides confinement normal to the substrate
Data Source
AI summary
A guiding element suitable for integrated optics and transmission in the visible wavelength region includes a plurality of sub-wavelength sized regions in two parallel periodic arrangements embedded within a waveguide layer located on a planar substrate. The dielectric constant of each regions may be the same but different from that of the substrate, the waveguide layer, and the cladding. The periodicity, dimensions and shape of the regions of the periodic arrangement are selected to achieve the desired transmission and guiding of the incident radiation spectrum (e.g., parallel to the two periodic arrangements). A transparent layer with a dielectric constant between the dielectric constant of the periodic arrangement and the dielectric constant of the substrate/cladding provides confinement normal to the substrate.