Surface Plasmon Light Source Polarization Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In projection-type display devices, the conversion of random polarization to specific polarization using existing planar illumination devices increases the etendue, leading to inefficient use of light from the light source as projection light.
Innovation Solution
A light source with a relief structure at the interface between a metal layer and a transparent dielectric layer, where the relief structure functions as a surface plasmon excitation means, allowing for the conversion of random polarization to specific polarization without increasing the etendue, by using a diffraction grating to excite and generate light with a particular polarization component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a planar illumination device with microprism is used to convert random polarization into specific polarization, then the polarization conversion is achieved, but the etendue is increased and light efficiency is reduced
Solution Approach 1:
The invention changes the structural parameters of the illumination device by replacing the microprism with a relief structure (diffraction grating) that has specific periodic features. This parameter change enables polarization conversion while controlling the etendue, as the relief structure can be designed with optimal period and depth to achieve the desired polarization effect without excessive light scattering that would increase etendue.
Solution Approach 2:
The invention introduces a new dimensional approach by using a relief structure with periodic variations in the vertical dimension (depth) rather than relying on angular redirection in the horizontal dimension. The relief structure creates surface plasmon excitation through vertical field components, enabling polarization conversion through a different physical mechanism that doesn't inherently increase etendue.
2Adaptability or versatility
If light propagates in various directions to strike the first boundary in various directions for polarization conversion, then random polarization is converted to specific polarization, but surface plasmons propagating in various directions are produced and light is emitted in various directions increasing etendue
Solution Approach 1:
The relief structure creates localized surface plasmon excitation at specific locations where the periodic structure matches the incident light wavelength and angle. This local quality approach ensures that only light within a specific angular range is converted, rather than converting light from all directions, thereby controlling the etendue while achieving polarization conversion for the relevant light cone.
3Adaptability or versatility
If a relief structure with periodic pattern is used to excite surface plasmon, then polarization conversion is achieved, but the structure complexity increases
Solution Approach 1:
The relief structure can be segmented into multiple zones with different periodic patterns or depths, allowing optimization for different wavelengths or angular ranges. This segmentation enables the device to achieve high polarization conversion efficiency across a broader spectrum while maintaining manufacturability through modular design approaches.
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 solution effectively converts random polarization into specific polarization without increasing the etendue, thereby improving the efficiency of light usage in projection-type display devices.
Implementation Method 1
a relief structure that functions as surface plasmon excitation means for exciting a surface plasmon by a particular polarization component in a polarization direction perpendicular to a first direction coplanar with an interface between the metal layer and the first transparent dielectric layer in light from the emission layer incident on the interface
Implementation Method 2
light generation means for generating light having the same polarization component as the particular polarization component from the surface plasmon generated at the interface between the metal layer and the first transparent dielectric layer according to the surface plasmon excited by the particular polarization component through the surface plasmon excitation means
Data Source
AI summary
A light source capable of solving a problem in which the etendue is increased when random polarization is converted into a specific polarization is provided. A relief structure that functions as surface plasmon excitation means for exciting a surface plasmon by a specific polarization component in a polarization direction perpendicular to a first direction in an interface between metal layer 15 and first cover layer 14 in light from emission layer 13 incident on the interface is formed at the interface. The relief structure is periodic in a second direction. Projections 21A of the relief structure are extended along the first direction. A light generation means for generating light having the same polarization component as the particular polarization component from the surface plasmon generated at the interface between metal layer 15 and first cover layer 14 according to the surface plasmon excited by the particular polarization component through the surface plasmon excitation means is formed at the interface between metal layer 15 and second cover layer 16.