Edge-Emitting Semiconductor Laser With N-Doped Waveguide
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Solution Overview
Problem
Conventional edge-emitting semiconductor lasers with p-doped waveguides face high series resistance due to low hole mobilities, which can increase threshold current and losses, making it challenging to achieve low series resistance and high efficiency at high currents.
Innovation Solution
The design incorporates an overall waveguide with a first and second n-doped layer, where the second n-doped layer has a higher refractive index, and minimizes p-doped layers to reduce series resistance, while using undoped layers to enhance the confinement factor of the fundamental laser mode, thereby guiding the radiation efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If p-doped layers are used in the waveguide, then the waveguide can be formed, but the series resistance increases due to low hole mobilities
Solution Approach 1:
The patent inverts the conventional doping approach by using n-doped layers instead of p-doped layers for the waveguide structure. This inversion allows the use of electrons (high mobility) instead of holes (low mobility) to form the waveguide, thereby reducing series resistance while maintaining waveguide functionality.
Solution Approach 2:
The patent changes the doping type parameter from p-type to n-type in the waveguide layers. This parameter change fundamentally alters the charge carrier type from holes to electrons, exploiting the higher electron mobility to reduce series resistance while maintaining the waveguide's optical confinement properties through refractive index differences.
2Loss of energy
If n-doped layers are used instead of p-doped layers, then series resistance decreases due to high electron mobility, but the refractive index profile must be optimized to maintain mode confinement
Solution Approach 1:
The patent applies local quality by creating distinct n-doped layers with different refractive indices at different positions within the waveguide structure. The second n-doped layer (adjacent to the active zone) has a higher refractive index than the first n-doped layer, creating localized refractive index variations that confine the fundamental mode while allowing the use of n-doping throughout for low series resistance.
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 approach results in a semiconductor laser with lower series resistance and higher efficiency, as more than half of the fundamental mode intensity is concentrated in the second n-doped layer and active zone, reducing the occurrence of higher-order modes and optical losses.
Implementation Method 1
the refractive index n2 of the second n-doped layer is greater by an amount dn than the refractive index n1 of the first n-doped layer
Implementation Method 2
an overall waveguide which is suitable for guiding the radiation generated in the active zone within the semiconductor laser
Data Source
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AI summary
The invention relates to an edge-emitting semiconductor laser comprising an active, radiation-generating zone (1) and a full waveguide (8) that is suitable for guiding the radiation generated in the active zone (1) inside the semiconductor laser. The full waveguide (8) comprises a first n-doped layer (4) and a second n-doped layer (5) arranged between the first n-doped layer (4) and the active zone (1). The refractive index n2 of the second n-doped layer (5) is higher than the refractive index n1 of the first n-doped layer (4) by the amount dn.