Laser Bar Thermal Balancing for Lower Lateral Far-Field Divergence
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Solution Overview
Problem
Laser bars exhibit asymmetric temperature profiles leading to wider lateral far-field divergence due to differing thermal distributions between inner and outer emitter structures, affecting overall bar performance.
Innovation Solution
Adjust the thermal power dissipation of outer emitter structures relative to inner structures by modifying their electrical and optical properties, such as increasing facet reflectivity, altering pumped region lengths, introducing unpumped areas, and implanting inert ions, to achieve a more uniform temperature profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of emitter structures is increased to achieve higher total output power, then the total output power increases, but the asymmetric temperature profile becomes more pronounced and lateral far-field divergence broadens
Solution Approach 1:
The patent applies local quality by differentiating the thermal management of outer emitter structures from inner emitter structures. Outer emitters receive enhanced cooling or reduced current injection compared to inner emitters, creating localized thermal adjustments that compensate for their inherently lower cooling efficiency and prevent asymmetric temperature profiles even as the total number of emitters increases.
Solution Approach 2:
The patent changes operational parameters (current injection levels, cooling rates) and structural parameters (thermal contact area, emitter spacing) of outer emitter structures to adjust their temperature characteristics. This allows the system to maintain uniform temperature profiles across all emitters while scaling up the total number of emitters for higher output power.
2Temperature
If outer emitter structures are cooled more effectively to reduce lateral far-field divergence, then temperature uniformity improves, but device complexity increases
Solution Approach 1:
The patent segments the thermal management system into distinct zones: inner emitter structures share a common cooling approach, while outer emitter structures receive dedicated thermal management adjustments. This segmentation allows targeted temperature control without requiring complete redesign of the entire thermal management system, thus limiting the increase in device complexity.
Solution Approach 2:
The patent designs the thermal management system to serve multiple functions simultaneously: it provides baseline cooling for all emitters while also delivering enhanced cooling to outer emitters, and it can adjust operational parameters to compensate for thermal asymmetries. This multi-functionality reduces the need for separate dedicated systems for each emitter type.
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
Reduces lateral far-field divergence by aligning outer emitter structures' temperatures with inner structures, enhancing thermal management and improving overall laser bar performance.
Implementation Method 1
the dissipated thermal power of the outer emitter structures facing the first and second sides, respectively, is adjusted relative to the inner emitter structures
Implementation Method 2
Charge carriers are injected via the p- and n-contacts into the active zone formed between the two contacts within the layer structure
Data Source
Figure 1a~1b
Figure 1c~2a
Figure 2b~2c
AI summary
The invention relates to a laser bar with a reduced lateral far-field divergence, in particular a laser bar with a consistent temperature profile in the lateral direction in order to reduce the lateral far-field divergence. A laser bar (1) according to the invention comprises a plurality of emitter structures which are arranged next to one another in parallel in the lateral direction, wherein, in order to vary the temperature profile in the lateral direction, the dissipated thermal output of the outer emitter structures is adapted to the inner emitter structures surrounded by the outer emitter structures.