Semiconductor Emitter Layout With Tunnel Diodes for High Power Density
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Solution Overview
Problem
Current semiconductor emitters for high-power laser diodes, such as those used in LiDAR applications, face limitations in achieving high optical power density while maintaining a compact design and low manufacturing costs, due to the need for thick epitaxial layers and multiple waveguides which lead to efficiency losses and coherence effects.
Innovation Solution
A semiconductor emitter design featuring a thin waveguide with multiple active quantum well structures and low-absorption tunnel diodes, where the tunnel diodes are positioned within the fundamental mode to enhance optical power density and reduce étendue, allowing for a single waveguide with high power density and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If thick epitaxial layers with multiple waveguides are used to achieve high optical power density, then optical power density increases, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges multiple active zones into a single waveguide structure, allowing multiple quantum well structures to coexist within one waveguide. This eliminates the need for separate waveguides while maintaining high optical power density through the combined emission of multiple active zones.
Solution Approach 2:
The patent transitions from a horizontal arrangement of multiple waveguides to a vertical stacking of multiple quantum well structures within a single waveguide. This dimensional change allows multiple active zones to be integrated without increasing lateral device complexity.
2Power
If thick epitaxial layers with multiple waveguides are used to achieve high optical power density, then optical power density increases, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple active zones into a single waveguide structure, reducing the total number of waveguide components that need to be manufactured and assembled. This simplification directly reduces manufacturing complexity and cost while maintaining high optical power output.
3Power
If multiple waveguides are used to achieve high optical power density, then optical power density increases, but coherence effects and interference increase
Solution Approach 1:
The patent extracts the harmful coherence effects by introducing tunnel diodes between adjacent quantum well structures. These tunnel diodes act as incoherent sources that disrupt the coherence between different active zones, eliminating interference while preserving the additive optical power.
4Device complexity
If a compact design is used to reduce device size, then device complexity decreases, but achieving high optical power density becomes difficult
Solution Approach 1:
The patent achieves compactness by stacking multiple quantum well structures vertically within a single waveguide rather than arranging multiple waveguides horizontally. This vertical integration maintains a compact footprint while achieving high optical power density through the combined emission of multiple active zones.
Solution Approach 2:
The patent nests multiple quantum well structures within a single waveguide, similar to nested dolls. This allows multiple active zones to be contained within one another spatially, achieving high power density in a compact structure without increasing device complexity.
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 achieves higher optical power densities with reduced étendue, lower manufacturing costs, and a more compact optical system, while minimizing coherence effects and interference, enabling efficient high-power laser emission.
Implementation Method 1
The at least one quantum well layer is configured in particular for the generation of laser radiation
Implementation Method 2
The at least one tunnel diode is located along a growth direction of the semiconductor layer sequence between two adjacent active zones
Implementation Method 3
a local intensity of an optical fundamental mode at the at least one tunnel diode is at least 35% or at least 50% or at least 60% or at least 80% or at least 90% of a maximum intensity of the fundamental mode
Data Source
AI summary
In an embodiment a semiconductor emitter includes a semiconductor layer sequence having a plurality of active zones, each active zone including at least one quantum well layer and at least two barrier layers between which the at least one quantum well layer is embedded, and at least one tunnel diode located along a growth direction of the semiconductor layer sequence between adjacent active zones, wherein a thickness of the at least one tunnel diode is at most 40 nm, and wherein a distance between adjacent barrier layers of adjacent active zones, facing the at least one tunnel diode, is at most 50 nm.