Light-Trapping Sheet With Diffraction Grating For Wide-Angle Coupling
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Solution Overview
Problem
Conventional light-trapping methods face challenges in efficiently transferring light between media of different refractive indices, limiting the range of angles and wavelengths that can be coupled into a light-transmitting layer, and resulting in attenuated light propagation.
Innovation Solution
A light-receiving device with a light-trapping sheet featuring a light-transmitting sheet and photoelectric conversion section, where the light-trapping sheet includes light-coupling structures with a diffraction grating that converts incident light into guided light, which is then radiated and totally reflected within the sheet, allowing for efficient photoelectric conversion of light across a wide range of angles and wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional grating coupling method is used to take light into a light-transmitting layer, then light coupling is achieved at specific angles and wavelengths, but only light satisfying predetermined conditions can be coupled while light falling out of conditions is not taken in
Solution Approach 1:
The light-trapping sheet is divided into multiple light-coupling structures distributed across the sheet. Each light-coupling structure functions as an independent light-coupling unit with its own diffraction grating, enabling parallel light coupling across different spatial locations. This segmentation allows the system to handle a broader range of incident light angles and wavelengths simultaneously, resolving the contradiction between adaptability and productivity.
Solution Approach 2:
Different regions of the light-trapping sheet are equipped with light-coupling structures having different diffraction grating parameters (pitch, orientation, depth). This local differentiation enables each region to optimize coupling for specific angle and wavelength ranges, collectively covering a broad spectrum of incident light conditions while maintaining high coupling efficiency across the entire sheet.
2Loss of energy
If light is propagated between two light-propagating media of different refractive indices, then transmission and reflection occur at the interface, but it is difficult to transfer light with high efficiency between the media
Solution Approach 1:
The light-coupling structure acts as an intermediary between the external light source and the light-transmitting layer. The diffraction grating within this intermediate structure modifies the incident light's propagation characteristics, enabling efficient coupling into the light-transmitting layer by matching impedance and reducing reflection losses at the interface.
Solution Approach 2:
The diffraction grating changes the propagation parameters (angle, wavelength, mode) of incident light to match the requirements of the light-transmitting layer. By adjusting the grating pitch, depth, and orientation, the system optimizes light coupling efficiency across different refractive index boundaries without requiring complex multi-layer structures.
3Productivity
If a light-trapping sheet with light-coupling structures is used to confine and convert incident light, then energy conversion efficiency is enhanced, but the area and number of photoelectric conversion sections required is reduced
Solution Approach 1:
Multiple light-coupling structures are merged into a single integrated light-trapping sheet that works in conjunction with the photoelectric conversion section. This unified structure concentrates and directs incident light more effectively onto the photoelectric conversion area, increasing the energy conversion efficiency per unit area and reducing the total area needed for the same power output.
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 enables efficient photoelectric conversion of light by confining it within the sheet, improving energy conversion efficiency and reducing the area and number of photoelectric conversion sections required, thereby enhancing the performance and cost-effectiveness of the light-receiving device.
Implementation Method 1
the third light-transmitting layer has a diffraction grating parallel to the first and second principal surfaces of the light-transmitting sheet
Implementation Method 2
it is possible to efficiently perform photoelectric conversion of light that has been taken in by utilizing total reflection of light
Data Source
AI summary
A light-receiving device of the present disclosure includes a light-trapping sheet, and a photoelectric conversion section optically coupled thereto. The light-trapping sheet includes: a light-transmitting sheet; and a plurality of light-coupling structures arranged in an inner portion of the light-transmitting sheet. The light-coupling structure includes first, second and third light-transmitting layers. A refractive index of the first and second light-transmitting layers is smaller than that of the light-transmitting sheet; and a refractive index of the third light-transmitting layer is larger than those of the first and second light-transmitting layers. The third light-transmitting layer has a diffraction grating parallel to the light-transmitting sheet. At least a part of the photoelectric conversion section is located along an outer edge of at least one of the surfaces of the light-transmitting sheet.