Thin Film Waveguide Light Concentrator with Nanopatterned Excitation Layer
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Solution Overview
Problem
Conventional passive thin film waveguides struggle to efficiently couple light into lateral guided modes due to symmetry issues between excitation and extraction, leading to limited concentration factors and increased complexity and cost in luminescent solar concentrators.
Innovation Solution
A thin film waveguide with a nanopatterned discontinuous excitation layer, preferably made of metal like silver, is used to excite lateral guided modes at nodes within the waveguide, breaking planarity and allowing for efficient light coupling without affecting propagating modes, thereby enabling flexible and efficient light concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a perfectly planar passive dielectric thin film waveguide with smooth parallel surfaces is used, then the structure is simple and manufacturing is easy, but light coupling into guided lateral modes is impossible due to Snell's law
Solution Approach 1:
The patent introduces a nanopatterned discontinuous excitation layer that breaks the planarity and symmetry of the waveguide surface. This asymmetric structure enables light coupling into guided lateral modes by creating refractive index variations and scattering centers that satisfy the coupling conditions, while maintaining overall waveguide functionality.
Solution Approach 2:
The nanopatterned excitation layer is positioned specifically at the node position of the guided mode, where it locally modifies the optical properties without affecting the entire waveguide structure. This localized modification enables efficient light coupling while preserving the overall simplicity and manufacturability of the planar waveguide.
2Ease of operation
If measures are taken to enable coupling light into the waveguide via at least one of its surfaces, then light coupling is improved, but extraction of the trapped light through the same surface is also improved, resulting in only a small amount of light being guided
Solution Approach 1:
The nanopatterned excitation layer is strategically positioned at the node position of the guided mode, where the mode intensity is minimal. This localized placement enables efficient light coupling into the waveguide while minimizing light extraction through the same surface, as the node position naturally suppresses extraction. This resolves the symmetry problem by creating different optical properties at the excitation location versus other parts of the waveguide.
3Quantity of substance
If the waveguide thickness is in the range of a few hundred nanometers to a few micrometers, then the structure is compact and material consumption is reduced, but the collection area at the surface exceeds the cross section of the excited waveguide modes, limiting concentration efficiency
Solution Approach 1:
The patent changes the optical parameters of the waveguide by introducing the nanopatterned excitation layer, which modifies the mode distribution and confinement. This allows the thin film waveguide to effectively concentrate light despite the thin thickness, by creating strong optical confinement through the nanopatterned structure that compensates for the reduced physical thickness.
4Ease of operation
If a nanopatterned discontinuous excitation layer is introduced to enable light coupling, then light coupling efficiency is improved, but the structure complexity and manufacturing difficulty increase
Solution Approach 1:
The nanopatterned excitation layer is implemented only at the specific node position of the guided mode, rather than throughout the entire waveguide structure. This localized approach minimizes the added complexity while achieving the desired light coupling function. The rest of the waveguide maintains its simple planar structure, balancing performance improvement with manufacturing feasibility.
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 reduces propagation losses and allows for high concentration factors with minimal material consumption, enabling flexible and cost-effective light concentrators that can cover large areas without extensive electrical wiring.
Implementation Method 1
exciting in the thin-film-waveguide at least one lateral guided mode propagating in a direction being parallel to the surface of the thin film waveguide and perpendicular to the normal vector of the substrate surface by interaction, in particular scattering, diffraction or surface plasmon excitation of the incident light with a nanopatterned discontinuous excitation layer
Implementation Method 2
exciting in the thin-film-waveguide at least one lateral guided mode propagating in a direction being parallel to the surface of the thin film waveguide and perpendicular to the normal vector of the substrate surface by interaction, in particular scattering, diffraction or surface plasmon excitation of the incident light
Implementation Method 3
exciting in the thin-film-waveguide at least one lateral guided mode propagating in a direction being parallel to the surface of the thin film waveguide and perpendicular to the normal vector of the substrate surface by interaction, in particular scattering, diffraction or surface plasmon excitation of the incident light
Implementation Method 4
In a perfectly planar passive dielectric thin film waveguide with smooth parallel surfaces an excitation of guided lateral modes from the outside through one of these surfaces is impossible (Snell's law). In fact this can be accomplished by braking the planarity with refractive index variations, backside scattering or diffractive elements.
Data Source
Figure 1
Figure 2a~2f
Figure 3a~3g
AI summary
The invention relates to a method for concentrating light by coupling light into a thin film waveguide (2, 4) arranged on a substrate (1), in particular via at least one of its parallel surfaces, the method further comprising the step of exciting in the thin-film-waveguide (2, 4) at least one lateral guided mode (5) having at least one node (6), preferably exactly one node (6), by interaction, in particular scattering, diffraction or surface plasmon excitation of the incident light with a nanopatterned discontinuous excitation layer (3) of material, in particular metal, preferably silver, the nanopatterned discontinuous excitation layer (3) being arranged in the thin-film-waveguide (2,4) at the position of the at least one node (6) of the guided lateral mode (5). The invention furthermore relates to a light concentrator comprising a thin film waveguide (2, 4) deposited on a substrate (1), the thin film waveguide (2, 4) having at least two parallel surfaces, light being coupable into the thin film waveguide (2, 4) via at least one of these surfaces, wherein the thin film waveguide (2, 4) is established as a collecting thin film waveguide (2, 3, 4) for collecting light by arranging a nanopatterned discontinuous excitation layer (3) of material, in particular of metal and preferably of silver at a position corresponding to the node position (6) of a guided mode (5) to be excited in the collecting thin film waveguide (2, 3, 4). The invention also relates to a method of fabricating such a light concentrator.