Thin Film Lithium Niobate Waveguide Core Thickness Optimization
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Solution Overview
Problem
Optical modulators face a trade-off between preventing crosstalk and maintaining modulation efficiency and coupling efficiency, as reducing the thickness of optical waveguide cores to prevent crosstalk leads to weakened light confinement and degraded efficiency.
Innovation Solution
The optical device features an X-cut or Y-cut thin film Lithium Niobate (LN) layer with a first optical waveguide formed perpendicular to the crystal axis, and a second optical waveguide connected to it, where at least part of the first waveguide's core is thicker than the second waveguide's core, improving modulation and coupling efficiency while preventing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of optical waveguide cores is reduced to prevent crosstalk, then crosstalk is suppressed, but light confinement is weakened and modulation efficiency and coupling efficiency are degraded
Solution Approach 1:
The patent applies local quality by creating different core thicknesses in different regions of the optical waveguide. The first optical waveguide has a thicker core in specific regions compared to the second optical waveguide, allowing localized optimization of light confinement and modulation efficiency in critical areas while maintaining overall system performance and suppressing crosstalk through the thickness difference between waveguides.
2Reliability
If the thickness of optical waveguide cores is increased to improve light confinement and efficiency, then modulation efficiency and coupling efficiency are improved, but crosstalk between waveguides increases
Solution Approach 1:
The patent employs asymmetry by designing the first and second optical waveguides with different core thicknesses. The first optical waveguide has a thicker core than the second optical waveguide, creating an asymmetric structure that optimizes light confinement and modulation efficiency in the first waveguide while the thinner second waveguide minimizes crosstalk, achieving a balance between these competing requirements.
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 configuration enhances modulation and coupling efficiency while effectively preventing crosstalk by optimizing the thickness and orientation of optical waveguides, addressing the trade-off between these performance metrics.
Implementation Method 1
if a voltage is applied to the signal electrode, an electric field in a vertical direction with respect to the surface of the optical modulator is generated inside the optical waveguide. The refractive index of the optical waveguide varies due to the electric field; therefore, the phase of light propagating in the optical waveguide is changed and it is thus possible to modulate the light.
Implementation Method 2
The refractive index of the optical waveguide varies due to the electric field; therefore, the phase of light propagating in the optical waveguide is changed
Data Source
AI summary
An optical device includes a thin film Lithium Niobate (LN) layer, a first optical waveguide, and a second optical waveguide. The thin film LN layer is an X-cut or a Y-cut LN layer. The first optical waveguide is an optical waveguide that is formed on the thin film LN layer along a direction that is substantially perpendicular to a Z direction of a crystal axis of the thin film LN layer. The second optical waveguide is an optical waveguide that is routed and connected to the first optical waveguide. At least a part of a core of the first optical waveguide is made thicker than a core of the second optical waveguide.