Three-Waveguide Optical Coupling for Low-Loss LiDAR Modulation
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Solution Overview
Problem
Silicon photonics devices face challenges with light loss as transmission distance increases, and silicon nitride's electrical insulation properties hinder the implementation of high-speed electro-optic modulators.
Innovation Solution
An optical device is designed with a first waveguide having a high refractive index core, a second waveguide with a low refractive index core, and a third waveguide with an intermediate refractive index core between them, facilitating efficient light propagation and modulating capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If silicon waveguide is used for light transmission, then light transmission efficiency is improved, but light loss increases as transmission distance increases
Solution Approach 1:
The patent introduces a third waveguide with intermediate refractive index between the silicon waveguide (high refractive index) and silicon nitride waveguide (low refractive index). This intermediate waveguide acts as a mediator to facilitate gradual refractive index transition, reducing reflection and scattering losses at material interfaces, thereby enabling efficient light transmission over longer distances.
Solution Approach 2:
The patent systematically varies the refractive index parameter across three different waveguide materials (silicon, intermediate material, silicon nitride) to create a gradient transition. This parameter change strategy allows optimal balance between light confinement (high refractive index) and low loss transmission (gradual index transition), solving the contradiction between transmission efficiency and distance.
2Adaptability or versatility
If silicon nitride is used for optical waveguide, then visible light to near-infrared transmission is improved, but electro-optic modulator implementation becomes difficult
Solution Approach 1:
The patent divides the optical waveguide system into three separate waveguide segments, each with specific material properties. The first waveguide (silicon) enables electro-optic modulation, the second waveguide (silicon nitride) provides broad wavelength transmission, and the third waveguide (intermediate material) connects them. This segmentation allows each segment to specialize in its strength while the system as a whole achieves both modulating capability and wavelength versatility.
Solution Approach 2:
The patent creates a multi-functional optical system where different waveguide materials serve different functions. The silicon-based waveguide provides electro-optic functionality, the silicon nitride waveguide provides broad spectral coverage, and the intermediate waveguide provides coupling functionality. This multi-functionality resolves the contradiction by making the overall system capable of both modulation and wide wavelength operation.
3Device complexity
If direct coupling between high refractive index and low refractive index waveguides is implemented, then device complexity is reduced, but light propagation efficiency decreases
Solution Approach 1:
The patent introduces an intermediate waveguide as a mediator between the high refractive index silicon waveguide and the low refractive index silicon nitride waveguide. This intermediate structure with moderate refractive index reduces the abruptness of the index transition, minimizing reflection and scattering losses while maintaining a relatively simple overall device structure.
Solution Approach 2:
The patent solves the coupling problem by adding a dimensional aspect to the refractive index transition - instead of a direct two-material interface, it creates a three-material gradient transition. This dimensional expansion in material composition space allows smoother optical field transition, reducing losses while keeping the geometric structure relatively simple.
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 optical device achieves reduced light loss and improved modulating capabilities, enabling efficient light propagation across a wide wavelength range and supporting high-speed optical communication.
Implementation Method 1
a third waveguide including a third core between the first waveguide and the second waveguide and having a refractive index that is less than the refractive index of the first core and greater than the refractive index of the second core
Data Source
AI summary
An optical device according to various example embodiments includes a first waveguide including a first core, a second waveguide including a second core spaced apart from the first waveguide and having a refractive index less than that of the first core, and a third waveguide disposed between the first waveguide and the second waveguide and including a third core having a refractive index less than the refractive index of the first core and greater than the refractive index of the second core.