Periodic Antenna Array Enhances Wavelength Conversion Efficiency
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Solution Overview
Problem
Existing illumination devices face challenges with heat management, efficiency, and emission directionality due to Stokes losses in wavelength conversion processes, requiring thick phosphor layers that lead to high local heat dissipation and reduced conversion efficiency, and exhibit limited use in low étendue applications like projection systems and automotive headlights.
Innovation Solution
An illumination device incorporating a periodic antenna array in close proximity to the wavelength conversion medium to support surface lattice resonances, enhancing excitation and emission efficiency, allowing for thinner wavelength conversion media and improved control over light color, directionality, and polarization, thereby modifying the illumination distribution from Lambertian to a more confined solid angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a thick wavelength conversion medium is used to improve absorption efficiency, then the absorption strength increases, but the local heat dissipation increases and the device complexity increases
Solution Approach 1:
The patent changes the optical parameters of the system by introducing a periodic antenna array that supports surface lattice resonances. This resonance structure enhances the local electromagnetic field and increases the absorption efficiency without requiring a thicker phosphor layer, thereby reducing heat dissipation while maintaining energy conversion efficiency.
Solution Approach 2:
The periodic antenna array acts as an intermediary between the incident light and the wavelength conversion medium. It mediates the light-matter interaction by supporting surface lattice resonances that enhance absorption, allowing thin phosphor layers to achieve high absorption efficiency without the heat management issues associated with thick layers.
2Use of energy by moving object
If a thick wavelength conversion medium is used to improve absorption efficiency, then the absorption strength increases, but the device complexity increases
Solution Approach 1:
The patent modifies the optical parameters by incorporating a periodic antenna array with specific geometric parameters (period, antenna shape, size) that support surface lattice resonances at the excitation wavelength. This enables high absorption efficiency in thin phosphor layers, avoiding the need for complex thick-layer structures while maintaining performance.
3Ease of manufacture
If a flat emission surface is used, then the manufacturing is simple, but the emission directionality is poor
Solution Approach 1:
The patent changes the emission characteristics by introducing a periodic antenna array that supports surface lattice resonances. This resonance structure naturally directs the emitted light in specific directions determined by the resonance conditions, providing directionality control without requiring complex beam shaping optics while maintaining manufacturing simplicity.
4Ease of operation
If traditional optical elements are used for beam shaping, then the illumination distribution can be controlled, but the device complexity increases and alignment precision is required
Solution Approach 1:
The periodic antenna array serves as an intermediary that integrates beam shaping and directionality control directly at the emission interface. It eliminates the need for separate beam shaping optical elements by providing inherent directionality through surface lattice resonances, reducing device complexity and alignment requirements while maintaining illumination distribution control.
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 enhances the efficiency of wavelength conversion processes, reduces heat dissipation, and improves the suitability of the device for low étendue applications by increasing the intensity and directionality of light emission, with potential enhancements of up to a factor of 10-50 in certain wavelength-angle regions compared to traditional Lambertian emission profiles.
Implementation Method 1
a periodic antenna array disposed in close proximity to the wavelength conversion medium and arranged such that the antenna array supports surface lattice resonances arising from diffractive coupling of localized surface plasmon resonances in individual antennas
Implementation Method 2
surface lattice resonances arising from diffractive coupling of localized surface plasmon resonances in individual antennas
Implementation Method 3
surface lattice resonances arising from diffractive coupling of localized surface plasmon resonances in individual antennas
Implementation Method 4
The excitation efficiency depends on the absorption strength of the phosphor at the primary wavelength light emitted by the LED
Implementation Method 5
The emission efficiency is influenced by both the extent to which the absorbed energy (i.e. primary wavelength light) is converted into emitted energy (i.e. secondary wavelength light)
Implementation Method 6
a light source arranged to emit light at a primary wavelength
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
Proposed is an illumination device (100), comprising a light source (110) such as an LED or a laser diode, a wavelength conversion medium (120) such as a phosphor, and a periodic antenna array(300) made of a highly polarisable material such as a metal. The light source emits primary wavelength light that at least partially is converted in secondary wavelength light by the wavelength conversion medium. The periodic antenna array is positioned in close proximity to the wavelength conversion medium and functions to enhance the efficiency of the absorption and/or emission processes in the wavelength conversion medium through the coupling of the incident primary wavelength light or the emitted secondary light to surface lattice resonances that arise from the diffractive coupling of localized surface plasmon polaritons in the individual antennas of the array. This is especially advantageous for forming low étendue illumination device suitable for use in projection systems, or for controlling the directionality, the polarization, and/or the color of the secondary wavelength light.