Multi-Cavity Optical Modulator for Broadband LED Intensity
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Solution Overview
Problem
Conventional Fabry-Perot interferometers with single cavities struggle to effectively modulate light intensity for sources with wide spectral bandwidths, such as LEDs, due to limited refractive index change, resulting in small differences between on-transmission and off-transmission light intensities.
Innovation Solution
An optical modulator with multiple resonance cavities, including distributed Bragg reflector layers and electric-optical layers, where different voltages are applied to adjust the refractive indices of the electric-optical layers to maximize light transmission during on-transmission and minimize it during off-transmission, using a transparent substrate and alternating high and low refractive index layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single cavity Fabry-Perot interferometer is used, then the device complexity is reduced, but the light intensity ratio between on-transmission and off-transmission status cannot be effectively increased for light sources with wide spectral bandwidth
Solution Approach 1:
The single cavity is divided into multiple cavities (first, second, and third cavities) with different optical path lengths. Each cavity targets a specific wavelength range, allowing the device to effectively modulate light across a wide spectral bandwidth while maintaining high light intensity ratio between on and off transmission states.
2Illumination intensity
If the refractive index change of the material is increased, then the light intensity difference between on-transmission and off-transmission status improves, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Different cavities are designed with specific refractive index requirements tailored to their function. The first cavity uses a refractive index suitable for its wavelength range, while subsequent cavities use different refractive indices optimized for their respective ranges. This localized optimization achieves high light intensity modulation without requiring uniform high complexity throughout the entire device.
3Adaptability or versatility
If multiple resonance cavities with different optical path lengths are stacked, then the adaptability to light sources with broad bandwidth is improved, but the number of layers and device complexity increase
Solution Approach 1:
Instead of increasing the complexity of a single cavity by adding more layers within one cavity, the patent extends the solution into a new dimension by stacking multiple cavities with different optical path lengths. This dimensional approach allows coverage of broad bandwidth through wavelength division multiplexing, where each cavity handles a specific wavelength range, achieving adaptability without excessive layer multiplication.
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 design significantly increases the light intensity ratio during on-transmission to off-transmission, enhancing the optical modulator's performance for LEDs with broad bandwidths while reducing the number of layers and simplifying manufacturing.
Implementation Method 1
applying a first voltage to a first optical layer of a first resonance cavity, so as to change a refractive index of the first electric-optical layer; and applying a second voltage to a second optical layer of a second resonance cavity, so as to change a refractive index of the second electric-optical layer
Implementation Method 2
The DBR layer may include an interfacial layer, and a high refractive index layer and a low refractive index layer that are alternately stacked in limited repetition
Implementation Method 3
first and second resonance cavities sequentially stacked on the transparent substrate, wherein the first and second resonance cavities each include an electric-optical layer
Implementation Method 4
first and second resonance cavities sequentially stacked on the transparent substrate
Data Source
AI summary
Provided are a high-speed optical modulator and a method of modulating light by using the same. The optical modulator includes first and second resonance cavities that are sequentially stacked on a transparent substrate, wherein the first and second resonance cavities each include an electric-optical layer. According to the method, first and second voltages having different sizes are simultaneously applied respectively to the first and second resonance cavities, and then for the other configuration of the modulator mutually interchanged voltages are applied.