Surface Emitting Laser Oxide Layer Design for Thermal Stress Reduction
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Solution Overview
Problem
Conventional methods for reducing the capacitance of oxide layers in surface emitting laser devices, such as ion implantation and tapered oxide layers, are complex and prone to thermal stress-induced breakage due to inflection points.
Innovation Solution
A laser device with a current confinement layer featuring an oxide layer that extends in a parallel plane from the edge to the center without inflection points, formed by epitaxial growth and oxidation in a water vapor atmosphere, reducing thermal stress and improving manufacturing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion implantation method is used to increase oxide layer thickness, then capacitance is reduced, but manufacturing complexity increases and yield decreases
Solution Approach 1:
The patent replaces the ion implantation method (mechanical/physical process) with a chemical oxidation process using water vapor atmosphere. This substitution simplifies the manufacturing process by eliminating complex ion implantation equipment and procedures while achieving the same goal of increasing oxide layer thickness and reducing capacitance.
Solution Approach 2:
The patent changes the oxidation parameters by controlling the water vapor atmosphere conditions and oxidation time to achieve uniform oxide layer growth. This parameter control allows for precise thickness adjustment without the complexity of ion implantation, reducing manufacturing difficulty while maintaining capacitance reduction effectiveness.
2Reliability
If tapered oxide layer is formed to increase thickness, then capacitance is reduced, but thermal stress causes breakage at inflection points
Solution Approach 1:
The patent applies local quality by creating a uniform oxide layer thickness across the current confinement layer surface, avoiding the tapered structure with inflection points. This uniform distribution eliminates stress concentration points while maintaining the capacitance reduction effect, thereby improving thermal shock resistance.
Solution Approach 2:
Instead of forming a tapered oxide layer (thicker at edges, thinner at center), the patent inverts this approach by forming a uniform or centrally-thicker oxide layer through controlled oxidation from water vapor. This inversion eliminates the inflection points that cause stress concentration and thermal shock failure.
3Speed
If oxide layer thickness is increased to reduce capacitance, then high-speed operation is enabled, but thermal stress concentration occurs at inflection points
Solution Approach 1:
The patent ensures uniform oxide layer distribution across the current confinement layer, eliminating local inflection points where thermal stress would concentrate. This uniform structure allows for increased thickness (lower capacitance) without creating weak points, enabling high-speed operation while avoiding thermal stress-related failures.
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 achieves reduced capacitance and enhanced thermal shock resistance, enabling high-speed operation of surface emitting laser devices from 25 Gbps to 45 Gbps with improved manufacturing reliability.
Implementation Method 1
forming an oxide layer, which extends from an edge of the current confinement layer in a parallel plane parallel to a surface of the substrate toward a center of the current confinement layer along the parallel plane, by heating the mesa post to a prescribed temperature in a water vapor atmosphere and keeping the mesa post at the prescribed temperature for a prescribed time to cause oxidization of the current confinement layer from a side surface of the mesa post
Data Source
AI summary
Provided is a laser device comprising a substrate, an active layer, and a current confinement layer. The current confinement layer includes an oxide layer that is formed extending from a edge of the current confinement layer in a parallel plane parallel to a surface of the substrate, toward a center of the current confinement layer along the parallel plane, and that does not have an inflection point between the edge and a tip portion formed closer to the center or has a plurality of inflection points formed between the edge and the tip portion.