Lithium Niobate Waveguide Stacking for Compact Optical Elements
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Solution Overview
Problem
Optical waveguides on substrates other than sapphire substrates lead to increased chip size when connected, and electrical connections with LN optical waveguides on sapphire substrates result in similar size increases, hindering miniaturization in optical communication systems.
Innovation Solution
An optical element is designed with a sapphire substrate and a silicon substrate, where a lithium niobate film is sandwiched between them, forming LN optical waveguides that are integrated with silicon photonics, allowing for wafer-level packaging and reducing chip size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If optical waveguides on different substrates are connected by mounting chips side by side within the same plane, then optical communication systems can be realized with multiple substrate types, but chip size increases unavoidably
Solution Approach 1:
The patent transitions from planar side-by-side mounting to three-dimensional vertical stacking, where the silicon substrate with silicon optical waveguide is positioned above the sapphire substrate with lithium niobate optical waveguide. This vertical arrangement in the thickness direction enables miniaturization while maintaining compatibility between different substrate types.
Solution Approach 2:
The patent implements a nested structure where the silicon substrate is mounted on the sapphire substrate, forming a stacked configuration. The lithium niobate optical waveguide on the sapphire substrate and the silicon optical waveguide on the silicon substrate are vertically aligned and optically coupled, creating a compact integrated structure that reduces overall chip size.
2Ease of operation
If chips with electric circuits and LN optical waveguides are mounted side by side within the same plane, then electrical connection of LN optical modulators can be achieved, but overall chip size increases
Solution Approach 1:
The patent positions the electric circuit on the silicon substrate in the vertical dimension above the sapphire substrate, rather than placing it side by side in the same plane. This vertical integration allows electrical connection terminals to be arranged in the thickness direction, reducing the lateral footprint of the chip while maintaining full electrical connectivity for LN optical modulator 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 effectively prevents the increase in chip size by integrating LN optical waveguides on different substrates, enabling miniaturization and facilitating high-speed optical communication systems.
Implementation Method 1
a first optical waveguide disposed in a manner of being sandwiched between the silicon substrate and the sapphire substrate, wherein the first optical waveguide is constituted of a lithium niobate film provided on one surface of the sapphire substrate
Implementation Method 2
a wafer bonding step of bonding one surface of the sapphire substrate having the first pattern formed in the first substrate patterning step and the one surface of the silicon substrate having the second pattern formed in the second substrate patterning step
Data Source
AI summary
An object is to provide an optical element in which an optical waveguide including lithium niobate and a silicon substrate are integrated. An optical element is an optical element including a sapphire substrate having a first optical waveguide, and a silicon substrate. The first optical waveguide is constituted of a lithium niobate film provided on one surface of the sapphire substrate. The first optical waveguide is disposed in a manner of being sandwiched between the silicon substrate and the sapphire substrate.