Optical Integrated Device Transparent Waveguide Current Blocking
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Solution Overview
Problem
In optical integrated devices, the current flowing through the interface between optically active elements and other elements degrades the characteristics and reliability due to crystal defects, and existing methods to offset electrodes are inaccurate, leading to increased optical absorption and reduced yield in manufacturing.
Innovation Solution
An optical integrated device is designed with a transparent waveguide having a higher bandgap energy material than the active layer, which acts as an optical path and is positioned between the semiconductor laser and the optical waveguide, preventing current from flowing through the regrowth interface and reducing degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode of the optically active element is offset from the interface between the optically active element and the other element, then the current flowing through the interface is restricted, but if the offset amount is too large, the optical absorption increases and the optically active element is degraded
Solution Approach 1:
A transparent waveguide layer is introduced as an intermediary component between the optically active element and the optical waveguide. This transparent waveguide has higher bandgap energy than the active layer, making it transparent to the emitted light while providing a physical barrier that prevents current from reaching the regrowth interface, thus solving both the reliability and optical absorption problems simultaneously
Solution Approach 2:
The invention changes the material parameter (bandgap energy) of the waveguide layer to be higher than the active layer, creating a transparent region that blocks current flow while allowing light transmission. This parameter change enables the waveguide to serve dual functions of electrical isolation and optical guidance without the drawbacks of traditional electrode offset methods
2Reliability
If the position of the interface and the position of the electrode are controlled with accuracy in a range of several microns, then the current flowing through the interface is decreased, but due to restrictions on the accuracy of lithography, the yield for the optical integrated device manufacturing process is decreased
Solution Approach 1:
The transparent waveguide acts as a buffer zone that decouples the precise positioning requirements between the electrode and the optical waveguide interface. By introducing this intermediary layer with specific optical and electrical properties, the system tolerates larger positioning variations during manufacturing while still achieving the desired current blocking effect, thereby improving manufacturing yield
3Reliability
If current flows from the electrode of the optically active element to the interface between the optically active element and the other element, then the generation and propagation of crystal defects is promoted, but the characteristics of the elements are degraded and the reliability of the optical integrated device is decreased
Solution Approach 1:
The transparent waveguide serves as a protective intermediary layer that physically separates the electrode from the regrowth interface. This intermediary structure blocks the harmful current flow that would otherwise generate and propagate crystal defects, thereby preventing degradation of element characteristics and improving device reliability
Solution Approach 2:
The invention uses the transparent waveguide's higher bandgap energy property to convert what would be a harmful current path into a beneficial current-blocking feature, while simultaneously maintaining optical transparency for the emitted light wavelength
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 solution effectively decreases current flow through the regrowth interface, enhancing the reliability and yield of the optical integrated device by minimizing crystal defects and optical absorption, while improving alignment tolerance and manufacturing accuracy.
Implementation Method 1
a transparent waveguide that is formed on the substrate between the first waveguide and the second waveguide, and includes a transparent core that serves as an optical path and is formed of a material having higher bandgap energy than the first optical path
Implementation Method 2
transparent core that serves as an optical path and is formed of a material having higher bandgap energy than the first optical path
Data Source
AI summary
Provided is an optical integrated device comprising a first waveguide that is formed on a substrate and includes a first optical path; an electrode formed on the first waveguide; a second waveguide that is formed on the substrate and includes a second optical path; and a transparent waveguide that is formed on the substrate between the first waveguide and the second waveguide, and includes a transparent core that serves as an optical path and is formed of a material having higher bandgap energy than the first optical path. The electrode is formed above the first waveguide and is not formed above the transparent waveguide, and elements including the first waveguide are optically active elements that operate according to current injected thereto.