Ridge-Waveguide Laser Diode Lateral Current Injection
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Solution Overview
Problem
Semiconductor laser diodes with vertical current injection suffer from high power consumption and heat generation due to high resistance in p-type semiconductor layers, particularly in the ridge portion.
Innovation Solution
A ridge-waveguide semiconductor laser diode design that laterally injects current through side surfaces of the ridge portion, using an upper electrode that covers both side and upper surfaces, incorporating a current spreading layer and a superlattice structure in the upper cladding layer to reduce resistance and enhance heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If vertical current injection is used through the ridge portion, then the laser diode can be manufactured with conventional structures, but high power is consumed and heat is generated due to high resistance in p-type semiconductor layers
Solution Approach 1:
The patent transitions from vertical current injection (one-dimensional) to lateral current injection through side surfaces (adding a lateral dimension). The upper electrode is positioned on the side surface of the ridge portion to enable horizontal current flow, reducing the path length through high-resistance p-type layers and thereby lowering power consumption while maintaining manufacturability
Solution Approach 2:
The patent inverts the conventional current injection approach by placing the upper electrode on the side surface rather than the top surface of the ridge portion. This inversion of the electrode position enables lateral injection through low-resistance n-type layers instead of vertical injection through high-resistance p-type layers, effectively reducing power consumption
2Device complexity
If vertical current injection is used through the ridge portion, then the current injection structure is simple, but heat is generated due to high resistance in p-type semiconductor layers
Solution Approach 1:
The patent introduces lateral current injection as an additional dimension to the conventional vertical injection structure. By positioning the upper electrode on the side surface, current can flow horizontally through low-resistance n-type layers, providing an alternative heat-reduction pathway that maintains structural simplicity while lowering operating temperature
Solution Approach 2:
The patent introduces a current spreading layer as an intermediary component between the upper electrode and the active region. This layer facilitates lateral current distribution and provides a low-resistance pathway for current flow, acting as a mediator that reduces heat generation while maintaining the simplicity of the overall structure
3Use of energy by moving object
If lateral current injection through side surfaces is implemented, then power consumption is reduced, but the electrode structure becomes more complex
Solution Approach 1:
The patent applies local quality by positioning the upper electrode specifically on the side surface of the ridge portion rather than uniformly across the top. This localized electrode placement enables lateral current injection through low-resistance regions while minimizing the overall electrode structure complexity, achieving power reduction without excessive structural complication
4Ease of manufacture
If current is injected vertically through p-type layers, then the injection structure is conventional, but high resistance causes high operating voltage
Solution Approach 1:
The patent inverts the conventional injection approach by placing the upper electrode on the side surface to enable lateral current flow through n-type layers. This inversion bypasses the high-resistance p-type layers that cause high operating voltage, achieving lower voltage operation while maintaining a manufacturable structure
Solution Approach 2:
The patent adds a lateral current injection dimension to the conventional vertical injection structure. By enabling current flow in the horizontal direction through low-resistance n-type layers, the patent provides an alternative pathway that reduces operating voltage while keeping the injection structure manufacturable
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 reduces carrier injection resistance, lowers operating voltage and power consumption, and improves heat dissipation, resulting in lower operating temperatures and enhanced electrical characteristics.
Implementation Method 1
a current is laterally injected through side surfaces of a ridge portion
Implementation Method 2
improves heat dissipation, resulting in lower operating temperatures
Data Source
AI summary
A ridge-waveguide semiconductor laser diode with an improved current injection structure is provided. The ridge-waveguide semiconductor laser diode includes: a substrate; a lower multi-semiconductor layer formed on the substrate; an active layer formed on the lower multi-semiconductor layer; an upper multi-semiconductor layer having a ridge portion and formed on the active layer; and an upper electrode formed on the upper multi-semiconductor layer, wherein the upper electrode covers at least one side surface of the ridge portion.