Surface Emitting Laser Aperture Shaping via Segmented Mesa and Terrace
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Solution Overview
Problem
The existing surface-emitting lasers face challenges in reducing parasitic capacitance while maintaining a desired aperture shape, as the presence of unetched portions hinders effective oxidation of the reflector layer, leading to increased parasitic capacitance and deformation of the aperture.
Innovation Solution
A surface-emitting laser design featuring a mesa, terrace, and connecting portion with a high resistance region, where the wiring is placed on the top surfaces of the terrace and connecting portion, and a first groove is formed between the mesa and terrace, allowing for reduced parasitic capacitance and controlled oxidation of the upper reflector layer to achieve a desired aperture shape by inclining the connecting portion from the substrate direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wiring is arranged on a surface of the groove to reduce distance to conductive layers, then the parasitic capacitance is reduced, but the reflector layer cannot be oxidized properly and the aperture shape is deformed
Solution Approach 1:
The structure is divided into three distinct regions: mesa (oxidized region with aperture), terrace (unetched region for wiring), and connecting portion (linking the two). This segmentation allows the wiring to be placed on the terrace away from the mesa, reducing parasitic capacitance while preserving the mesa's oxidation process and aperture shape integrity.
Solution Approach 2:
The connecting portion is designed to extend in a direction inclined from the substrate direction, creating a three-dimensional structure that connects the mesa and terrace. This dimensional approach allows the wiring on the terrace to be spatially separated from the mesa's conductive layers, reducing parasitic capacitance without affecting the aperture formation.
2Manufacturing precision
If the unetched portion is removed to enable proper oxidation, then the aperture shape is improved, but the wiring distance to conductive layers increases and parasitic capacitance increases
Solution Approach 1:
The structure is divided into three distinct regions: mesa (oxidized region with aperture), terrace (unetched region for wiring), and connecting portion (linking the two). This segmentation allows the wiring to be placed on the terrace away from the mesa, reducing parasitic capacitance while preserving the mesa's oxidation process and aperture shape integrity.
Solution Approach 2:
The connecting portion acts as an intermediary structure that links the mesa and terrace. It provides a physical connection while maintaining spatial separation between the wiring area and the oxidized mesa region, enabling both proper oxidation for aperture formation and sufficient distance for low parasitic capacitance.
3Device complexity
If the wiring is placed close to conductive semiconductor layers, then the device complexity is reduced, but the parasitic capacitance is increased affecting high-frequency operation
Solution Approach 1:
The connecting portion is designed to extend in a direction inclined from the substrate direction, creating a three-dimensional structure that connects the mesa and terrace. This dimensional approach allows the wiring on the terrace to be spatially separated from the mesa's conductive layers, reducing parasitic capacitance without affecting the aperture formation.
Solution Approach 2:
The structure is divided into three distinct regions: mesa (oxidized region with aperture), terrace (unetched region for wiring), and connecting portion (linking the two). This segmentation allows the wiring to be placed on the terrace away from the mesa, reducing parasitic capacitance while preserving the mesa's oxidation process and aperture shape integrity.
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 effectively reduces parasitic capacitance and allows for the formation of an aperture with a desired shape, enhancing the laser's high-frequency operation and current confinement structure, thereby improving the overall performance of the surface-emitting laser.
Implementation Method 1
a step of oxidizing a part of the upper reflector layer from a side surface of the mesa so as to form an aperture surrounded by an oxide region
Implementation Method 2
forming a high resistance region by implanting ions into a portion of each of the lower reflector layer, the active layer, and the upper reflector layer
Data Source
AI summary
A surface emitting laser includes a lower reflector layer, an active layer , an upper reflector layer , and a wiring. The lower reflector layer, the active layer, and the upper reflector layer form a mesa, a terrace, and a connecting portion. A first groove is provided between the mesa and the terrace. The connecting portion connects the mesa and the terrace, and extends in a direction inclined from <011> direction of the substrate. A high-resistance region is formed in the terrace, in the connecting portion, and in a peripheral portion of the mesa. The wiring is provided on top surfaces of the terrace, the connecting portion, and the mesa. The mesa includes an oxide region extending from a side surface of the mesa and a current confinement structure including an aperture surrounded by the oxide region.