LED Emission Structure Using TE Waveguide Mode for Polarized Light
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing polarized light in LEDs, such as using polarizers or chemical engineering solutions, result in significant light loss, increased form factor, and reduced efficiency, particularly in top-emitting LEDs.
Innovation Solution
A structure for LEDs that promotes the emission of a transverse electric (TE) waveguide mode without the need for polarizers or chemical engineering, utilizing an emissive layer (EML) tuned to enhance TE waveguide mode emission and suppress other modes, combined with a diffraction grating to extract polarized light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a polarizer is added to thin-film LEDs to produce polarized light, then the required output polarized light is achieved, but significant light loss and increased form factor occur
Solution Approach 1:
The patent extracts the polarization function from external components (polarizers) and integrates it into the LED's internal waveguide structure. By designing the waveguide to naturally support TE mode propagation, the system achieves polarization without requiring separate polarizing components, thereby eliminating the associated light losses.
Solution Approach 2:
The waveguide structure serves as an intermediary that transforms the emission characteristics of the LED. By engineering the waveguide's geometric and material properties, it mediates between the isotropic emission of the LED and the anisotropic polarization requirement, coupling preferentially to TE modes while suppressing TM modes through controlled reflection and mode confinement.
2Illumination intensity
If a polarizer is added to thin-film LEDs to produce polarized light, then the required output polarized light is achieved, but the form factor increases
Solution Approach 1:
The patent merges the polarization function with the existing waveguide structure of the LED. Instead of adding separate polarizing components that would increase the form factor, the polarization capability is integrated into the waveguide's core design, allowing the same structural elements to perform both light guidance and polarization functions simultaneously.
Solution Approach 2:
The waveguide structure is designed to perform multiple functions: light transmission, mode confinement, and polarization generation. By making the waveguide universal in its functionality, the system eliminates the need for dedicated polarizing components, thereby maintaining a compact form factor while achieving the required polarized light output.
3Illumination intensity
If metal grating is added external to glass substrate to polarize emitted light, then polarized light is produced, but over 70% of light is absorbed by the metal grating
Solution Approach 1:
The patent replaces the mechanical metal grating system with an optical waveguide mode selection mechanism. Instead of using physical metal structures that absorb light, the system uses the optical properties of the waveguide (refractive index differences, geometric confinement) to selectively guide TE modes, thereby achieving polarization through optical rather than mechanical means and avoiding metal absorption losses.
Solution Approach 2:
The waveguide structure employs composite materials with carefully selected optical properties (different refractive indices for core and cladding layers) to achieve mode selectivity. This composite material approach enables polarization through constructive and destructive interference of electromagnetic modes rather than through metal reflection and absorption, significantly reducing energy loss.
4Illumination intensity
If chemical engineering solutions are used to align electric dipole moment uniaxially to produce polarized light, then polarized light is produced, but significant light loss occurs
Solution Approach 1:
The waveguide structure is designed to self-select TE modes through its inherent geometric and optical properties, without requiring external chemical treatments or alignment processes. The structure's own configuration (core-cladding refractive index difference, waveguide dimensions) automatically creates the conditions for TE mode preferential propagation, making the polarization function self-service and eliminating the need for lossy chemical engineering solutions.
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 structure achieves high polarization ratios exceeding 30% while maintaining a compact form factor, with over 80% of light coupled into the TE waveguide mode, improving efficiency and reducing light loss.
Implementation Method 1
In LEDs electrons and electrons holes recombine through the flow of current to release energy in the form of photons, light
Implementation Method 2
Energy propagates from the EML in a number of different propagation modes. Energy propagating within the structure, which acts as a waveguide, is referred to propagating in waveguide modes
Implementation Method 3
The structure may further comprise an optical component for diffracting the TE waveguide mode to emit light from the structure
Data Source
AI summary
A structure for emitting light is provided. The structure comprises an emissive layer (EML) positioned between electrodes. The EML is tuned such that emission of a transverse electric (TE) waveguide mode from the EML is promoted. The structure further comprises an optical component for diffracting the TE waveguide mode to emit light from the structure.