DFB Laser and EA Modulator Mesa Structure for High-Temperature Output
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Solution Overview
Problem
Existing semiconductor optical devices face challenges in achieving high output and high-speed modulation, particularly under high temperature conditions, due to insufficient current confinement in the light emitting region and increased parasitic capacitance in the modulator region.
Innovation Solution
The semiconductor optical device integrates a light emitting region and a modulator region with a specific structure, including a first mesa with an active layer, buried layers of different conductivity types, and a second mesa with a light absorption layer and a semi-insulating buried layer. This structure enhances current confinement and reduces parasitic capacitance, enabling high output and high-speed modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional integrated structure is used, then device integration is achieved, but current confinement in the light emitting region is insufficient
Solution Approach 1:
The device is divided into separate light emitting region and modulator region with distinct mesa structures. The light emitting region has its own mesa with specific buried layers for current confinement, while the modulator region has a separate mesa structure. This segmentation allows each region to be optimized independently for its specific function.
Solution Approach 2:
Different conductivity type buried layers are selectively placed in the light emitting region to provide local current confinement. The first and second buried layers with different conductivity types are positioned specifically in the light emitting region, while the modulator region has a different buried layer configuration, creating local quality differences that optimize each region's performance.
2Device complexity
If the modulator region structure is simplified, then device complexity is reduced, but parasitic capacitance increases
Solution Approach 1:
The modulator region is structured as a separate mesa with its own buried layers, distinct from the light emitting region. This segmentation allows the modulator to have a simplified overall structure while maintaining specific local features (buried layers) that control parasitic capacitance.
Solution Approach 2:
The modulator region employs a specific buried layer configuration (third buried layer with different conductivity type) that is localized to that region. This local quality difference between the modulator and light emitting regions enables the modulator to achieve low parasitic capacitance without complicating the entire device structure.
3Power
If output power is increased, then optical output is improved, but current leakage increases at high temperatures
Solution Approach 1:
The light emitting region features buried layers with different conductivity types positioned specifically to enhance current confinement. This local quality difference creates effective current blocking at the interfaces between regions, preventing current leakage even when high power is applied at elevated temperatures.
Solution Approach 2:
The device uses composite semiconductor structures with alternating conductivity types (n-type and p-type layers) in the light emitting region. This composite structure creates multiple current blocking interfaces that effectively confine current to the active region, maintaining reliability at high temperatures and high power levels.
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 proposed solution achieves strong current confinement in the light emitting region, allowing for high optical output even at high temperatures, while reducing parasitic capacitance in the modulator region for high-speed modulation.
Implementation Method 1
an electroabsorption (EA) type optical modulator
Data Source
AI summary
A semiconductor optical device, in which a light emitting region and a modulator region are integrated, includes a first mesa disposed in the light emitting region, protruding in a direction that intersects a light propagation direction, and including an active layer, first and second buried layers disposed on the first mesa in a direction that intersects the light propagation direction and sequentially stacked in a direction in which the first mesa protrudes, a first semiconductor layer disposed on the first mesa and the second buried layer, a second mesa disposed in the modulator region and including a light absorption layer, and a third buried layer disposed on the second mesa. The first semiconductor layer and the first buried layer each have a first conductivity type. The second buried layer has a second conductivity type different from the first conductivity type, and the third buried layer is a semi-insulating semiconductor layer.