Broad Stripe Laser Segmented Ridges for Thermal Management
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor lasers face limitations in output power due to thermal effects, and broad stripe lasers are prone to damage from high current densities, which restrict their optical output power and lifetime.
Innovation Solution
A broad stripe laser design featuring an epitaxial layer stack with trenches and ridges on the top side, where the ridges and trenches are less than 20 μm wide, allowing for index-guided individual stripes, which increases optical output power, reduces facet loading, and extends the laser's lifetime, while enabling controlled emission characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the output power of semiconductor lasers is increased, then the optical output power improves, but thermal effects worsen and limit the output power to a few hundred milliwatts in cw-operation
Solution Approach 1:
The broad stripe laser structure is segmented into multiple individual stripes (ridges) with widths of at most 20 μm, preferably at most 10 μm, and particularly preferably at most 7 μm. These ridges are arranged in a striped fashion on the top side of the layer stack, with adjacent ridges being at a distance from one another of at most 20 μm, preferably at most 10 μm. This segmentation divides the current and heat distribution across multiple smaller emission regions, reducing thermal effects while maintaining high total optical output power.
2Power
If high current densities are applied to broad stripe lasers, then the optical output power increases, but the ridges are damaged or even destroyed due to the thermal lens constricting the laser mode
Solution Approach 1:
The laser structure is divided into multiple narrow ridges separated by trenches, where at least one layer of the layer stack is at least partly removed in the trenches. This segmentation distributes the current density across multiple smaller ridges rather than concentrating it in a single broad stripe, reducing the risk of ridge damage while enabling higher total optical output power.
Solution Approach 2:
The ridges are designed with specific width constraints (at most 20 μm, preferably at most 10 μm, particularly preferably at most 7 μm) to optimize the balance between current density distribution and optical mode confinement. This local dimensional control ensures that each ridge can handle the current density without damage while maintaining efficient lasing action.
3Reliability
If the ridge width is reduced to at most 20 μm, then the facet loading is reduced and lifetime is increased, but the optical output power density must be optimized through precise ridge and trench dimensions
Solution Approach 1:
The ridges are designed with precise width constraints (at most 20 μm, preferably at most 10 μm, particularly preferably at most 7 μm) to optimize the balance between current density distribution and optical mode confinement. This local dimensional control ensures that each ridge can handle the current density without damage while maintaining efficient lasing action and appropriate optical output power density.
Solution Approach 2:
The dimensions of ridges and trenches are precisely controlled within specific ranges to optimize the trade-off between ridge strength/lifetime and optical performance. By adjusting ridge width, trench width, and ridge spacing within the specified limits, the laser achieves both reduced facet loading for improved lifetime and maintained optical output power density.
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 design enhances optical output power density, extends the laser's operational lifetime, and allows for optimized beam profiles by adjusting ridge width, distance, and trench depth, enabling targeted control of emission characteristics.
Implementation Method 1
A broad stripe laser of this type accordingly has on the top side preferably index-guided, closely adjacent individual stripes, so-called ridges
Data Source
AI summary
A broad stripe laser (1) comprising an epitaxial layer stack (2), which contains an active, radiation-generating layer (21) and has a top side (22) and an underside (23). The layer stack (2) has trenches (3) in which at least one layer of the layer stack (2) is at least partly removed and which lead from the top side (22) in the direction of the underside (23). The layer stack (2) has on the top side ridges (4) each adjoining the trenches (3), such that the layer stack (2) is embodied in striped fashion on the top side. The ridges (4) and the trenches (3) respectively have a width (d1, d2) of at most 20 μm.