Phosphor Surface Nanoantenna Layout for Fluorescence Extraction
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Solution Overview
Problem
In existing illumination devices, a portion of fluorescence generated by a wavelength converter is totally reflected and absorbed by nanoantennas without being extracted, leading to reduced light extraction efficiency.
Innovation Solution
A wavelength conversion device with a phosphor member having an uneven structure and nanoantennas on projecting portions, where the uneven structure includes recessed portions and projecting portions arranged at a pitch smaller than the fluorescence peak wavelength, enhancing fluorescence extraction and narrowing its angle through localized surface plasmon resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If nanoantennas are used to narrow the angle of fluorescence, then the angle of fluorescence emission is improved, but light extraction efficiency deteriorates due to total internal reflection and absorption of reflected light
Solution Approach 1:
The phosphor member surface is designed with local variations in refractive index through recessed portions and projecting portions. These local structural changes create localized regions that modify light propagation paths, enabling simultaneous angle narrowing and extraction efficiency improvement without requiring uniform structural modifications throughout the entire surface.
Solution Approach 2:
The recessed portions and projecting portions act as intermediary structures between the phosphor material and the nanoantennas. These intermediate features mediate the interaction between light and nanoantennas by providing additional optical paths and reducing direct total internal reflection at the phosphor-air interface, thereby preventing energy loss while maintaining angle narrowing functionality.
2Ease of manufacture
If a flat phosphor member surface is used, then manufacturing is simple, but light extraction efficiency is reduced due to total internal reflection
Solution Approach 1:
The phosphor member surface is segmented into multiple regions with different depths (recessed portions and projecting portions). This segmentation creates a multi-level surface structure that disrupts total internal reflection by providing multiple exit paths for light, thereby improving extraction efficiency while maintaining manufacturability through standard lithography and etching processes.
Solution Approach 2:
The solution transitions from a two-dimensional flat surface to a three-dimensional structured surface by introducing recessed portions and projecting portions with varying depths. This dimensional change adds optical path length and creates multiple interfaces for light extraction, significantly improving extraction efficiency without complicating the manufacturing process excessively.
3Shape
If the pitch of nanoantennas is reduced to narrow fluorescence angle, then angle control is improved, but manufacturing complexity increases
Solution Approach 1:
The invention merges the functions of the phosphor member surface structure and nanoantenna arrangement into a single integrated design. The recessed portions and projecting portions are positioned to coincide with nanoantenna locations, combining the light-modulating function of the surface structure with the angle-controlling function of the nanoantennas, thereby reducing overall device complexity while achieving effective angle narrowing.
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
Improves light extraction efficiency while achieving a narrowed angle of fluorescence emission by reducing total internal reflection and amplifying fluorescence with nanoantennas.
Implementation Method 1
a phosphor excited by the excitation light to emit a fluorescence
Implementation Method 2
a component exceeding a critical angle of a fluorescence generated by excitation of a phosphor in the wavelength converter with an excitation light is totally reflected by an interface between the wavelength converter and air
Implementation Method 3
enhancing fluorescence extraction and narrowing its angle through localized surface plasmon resonance
Data Source
AI summary
A wavelength conversion device includes a phosphor member and a plurality of nanoantennas. The phosphor member has one surface on which an excitation light is incident, includes a phosphor excited by the excitation light to emit a fluorescence, and has an uneven structure on another surface in an opposite side of the one surface. The uneven structure includes a plurality of projecting portions each provided in one direction along the other surface at a pitch smaller than a peak wavelength of the fluorescence. The plurality of nanoantennas are provided at upper surfaces of the plurality of projecting portions and made of a metal material.