Optical Waveguide Window Structure for Stable High-Power Laser Output
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Solution Overview
Problem
High-mesa semi-insulating embedded structures used in high-speed modulation semiconductor lasers face challenges with unstable operation due to return light from the laser chip end face, especially when attempting to increase output beyond conventional levels.
Innovation Solution
A semiconductor light source element with a high-mesa semi-insulating embedded window structure made of the same material as the overclad layer at the light emission end, along with a manufacturing method that involves removing the core layer at the window structure portion before growing the overclad layer, is employed to reduce return light and enhance output stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the laser output is increased to meet the need for higher power transmission, then the output power is improved, but the operation stability deteriorates due to return light from the end face
Solution Approach 1:
The patent extracts and removes the core layer at the end face portion to create a window structure, eliminating the source of return light reflection. By taking out the core layer and replacing it with a window structure made of the same material as the overclad layer, the invention removes the harmful reflective interface while maintaining optical transmission, thus resolving the contradiction between high power output and operational stability
Solution Approach 2:
The window structure acts as an intermediary element between the core layer and the external environment. This intermediate structure, made of the same material as the overclad layer, provides a transition zone that reduces the abrupt refractive index change at the end face, thereby minimizing return light reflection while allowing high power transmission
2Power
If a conventional window structure is applied to high-mesa semi-insulating embedding, then the output power can be increased, but crystal defects and voids occur due to abnormal growth on the (0 -1 -1) plane
Solution Approach 1:
The patent changes the growth parameters by performing selective removal of the core layer before overclad layer growth, and by controlling the embedded growth process to avoid abnormal growth on the (0 -1 -1) plane. This parameter change approach allows the window structure to be formed in high-mesa structures without causing crystal defects or voids, thus achieving both high power output and high manufacturing precision
Solution Approach 2:
The patent performs preliminary removal of the core layer at the end face portion before growing the overclad layer. This preliminary action prevents the formation of crystal defects and voids that would occur if the window structure were formed after complete overclad layer growth, as the removal is done at the optimal stage in the manufacturing process
3Speed
If the mesa height is increased to exceed 3 μm for high-speed modulation, then the modulation speed is improved, but embedded growth becomes difficult due to the 90 degree orientation difference between side walls and crystal plane
Solution Approach 1:
The patent applies local quality by creating a window structure with different material composition at the end face portion compared to the main body. The window structure is made of the same material as the overclad layer, while the rest of the structure maintains the original core-overclad configuration. This local differentiation allows high-mesa structures to achieve high-speed modulation without the embedded growth problems that would affect the entire structure
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 enables a semiconductor light source element with high output and high-speed modulation capabilities while minimizing return light issues, resulting in improved operational stability and performance.
Implementation Method 1
removing a core layer of a portion serving as the window structure by etching in a process before growing the overclad layer
Implementation Method 2
forming the same layer as the overclad layer crystal-grown on the core layer of the semiconductor optical waveguide at the portion of the window structure
Data Source
AI summary
Provided is a semiconductor light source element or an optical device including a semiconductor optical waveguide of a high-mesa semi-insulated embedded structure having a window structure made of the same material as an overclad layer at a light emission end, and a method for manufacturing thereof, in which an active layer at a portion of the window structure is removed, and then the same layer as the overclad layer is formed.