Surface Emitting Laser Proton Concentration Gradient
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Solution Overview
Problem
Current surface emitting lasers face limitations in achieving high-speed operations due to parasitic capacitance, which hinders their performance.
Innovation Solution
The surface emitting laser design incorporates a proton concentration gradient in the upper reflector layer, with a higher concentration in the second region to increase resistance and enable high-speed operation, while maintaining lower resistance in the first region for efficient current conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a uniform proton concentration is applied throughout the upper reflector layer, then the manufacturing process is simple, but the parasitic capacitance cannot be sufficiently reduced for high-speed operation
Solution Approach 1:
The patent applies local quality by creating different proton concentration levels in different regions of the upper reflector layer. The first region (under the electrode and light transmitting window) has a lower proton concentration to maintain current conduction, while the second region (surrounding area within the mesa) has a higher proton concentration to reduce parasitic capacitance. This spatial variation in proton concentration optimizes both electrical performance and manufacturing simplicity.
2Productivity
If the proton concentration is increased throughout the upper reflector layer to reduce parasitic capacitance, then high-speed operation is enabled, but current conduction efficiency deteriorates
Solution Approach 1:
The patent resolves this contradiction by applying local quality principles: the first region under the electrode and light transmitting window maintains lower proton concentration to ensure efficient current conduction, while the second region (surrounding area within the mesa) has higher proton concentration to reduce parasitic capacitance. This localized differentiation allows simultaneous optimization of both current conduction and high-speed operation.
3Reliability
If the proton concentration is decreased in the first region to improve current conduction, then current flow is enhanced, but parasitic capacitance reduction is compromised
Solution Approach 1:
The patent applies local quality by creating spatially differentiated proton concentration: the first region (under electrode and light transmitting window) has lower proton concentration optimized for current conduction, while the second region (surrounding area within the mesa) has higher proton concentration optimized for parasitic capacitance reduction. This resolves the contradiction by optimizing each region for its specific function.
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 design allows for higher cutoff frequencies, enabling the surface emitting laser to operate at high speeds by optimizing the proton concentration in specific regions, thereby reducing parasitic capacitance and enhancing performance.
Implementation Method 1
Literature with respect to such a surface emitting laser describes that protons are injected into a mesa area to reduce parasitic capacitance
Data Source
AI summary
A surface emitting laser includes a substrate, a lower contact layer disposed on the substrate, a semiconductor layer mesa including a lower reflector layer, an active layer, an upper reflector layer, and an upper contact layer which are laminated, in the order named, on the lower contact layer, an annular electrode disposed on the upper contact layer, and a light transmitting window situated inside the annular electrode to transmit laser light, wherein the upper reflector layer includes a first region and a second region, the first region being inclusive of an area situated directly below the electrode and the light transmitting window, the second region being inclusive of an area outside the mesa and inclusive of a surrounding area of the first region within the mesa, and wherein a proton concentration in the first region is lower than a proton concentration in the second region.