Multimode Interference Optical Coupler for Visible Light Integration
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Solution Overview
Problem
Current retinal projection displays face challenges in coupling multiple wavelengths of visible light due to uncoupled optical waveguides, leading to complex light control and the inability to integrate with lithium niobate film-based modulators, which limits miniaturization and efficiency.
Innovation Solution
A multimode interference (MMI) type optical coupler with tapered input and output ports is designed to couple multiple visible light wavelengths, including red, green, and blue, using a lithium niobate film for improved integration and miniaturization, allowing for efficient light modulation and reduced coupling loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If directional couplers made of glass-based material are used, then stability is improved, but coupling length becomes long and miniaturization is not possible
Solution Approach 1:
The patent changes the material parameter from glass-based to lithium niobate, which has different optical properties including higher refractive index. This material substitution enables achieving the same coupling effect in a shorter length, resolving the contradiction between stability and coupling length.
Solution Approach 2:
The patent employs composite structure by integrating lithium niobate substrate with metal electrodes and dielectric layers, creating a hybrid system that combines the advantages of different materials to achieve both stability and compact size.
2Device complexity
If optical waveguides are placed close to each other at emission part but not coupled, then structural simplicity is maintained, but optical axis control becomes complicated
Solution Approach 1:
The patent merges multiple optical waveguides into a single integrated optical coupler structure. By combining the waveguides and their coupling mechanisms into one unified component, it simplifies the overall structure while simultaneously improving optical axis control through the integrated design.
3Volume of moving object
If RGB optical coupler is designed for lithium niobate film integration, then miniaturization is enabled, but compatibility with existing glass-based systems is reduced
Solution Approach 1:
The patent segments the optical system into distinct functional modules: lithium niobate-based optical coupler for wavelength coupling, separate optical modulators for signal modulation, and independent waveguide structures. This modular segmentation enables miniaturization while maintaining compatibility through standardized interfaces between modules.
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 MMI optical coupler effectively couples multiple wavelengths, enabling smaller form factors and improved light modulation capabilities, enhancing the integration with lithium niobate film-based modulators and reducing coupling losses for retinal projection displays.
Implementation Method 1
The MMI type optical coupler is an optical coupler using characteristics in which a large number of modes generated within an optical coupler having a wide width interfere with each other for each wavelength and an image is formed (converged) at a specific position.
Implementation Method 2
a plurality of input taper portions which are tapered input ports, wherein the plurality of input taper portions are disposed on an input side of the optical coupling main body and a width of each of the plurality of input taper portions becomes narrower as it is away from a connection end with the optical coupling main body
Data Source
AI summary
The optical coupler is a multimode interference type optical coupler that couples a plurality of laser lights of different wavelengths. The optical coupler includes an optical coupling main body, two input taper portions which are tapered input ports that are disposed on the input side of the optical coupling main body and of which the width of each becomes narrower as it is away from a connection end with the optical coupling main body, and one output taper portion which is a tapered output port that is disposed on the output side of the optical coupling main body and of which the width becomes narrower as it is away from a connection end with the optical coupling main body.