Laser Bar Outer Emitter Tuning for Lower Far-Field Divergence
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Solution Overview
Problem
Conventional laser bars experience broad lateral far-field divergence due to asymmetric temperature profiles, where outer emitter structures have a different temperature distribution compared to inner structures, leading to broader far-field divergence and reduced performance.
Innovation Solution
The laser bar design adjusts the dissipated thermal power of outer emitter structures to match the temperature of inner structures by modifying their electrical and optical properties, such as increasing facet reflectivity, internal optical losses, and thermal resistance, to achieve a homogeneous temperature profile across all emitter structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of broad-area diode lasers is increased to achieve high total output power, then productivity is improved, but the temperature distribution becomes more asymmetric 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 are equipped with enhanced heat dissipation features (larger heat sinks, improved thermal coupling) tailored to their specific thermal challenges, while inner emitters maintain standard design. This localized adaptation resolves the temperature asymmetry caused by high emitter density without reducing total output power.
Solution Approach 2:
The patent changes thermal parameters (heat sink size, thermal conductivity, heat dissipation area) of outer emitter structures to compensate for their asymmetric thermal environment. By adjusting these parameters, the patent equalizes temperature profiles across all emitters even when densely packed, thereby maintaining both high productivity and temperature symmetry.
2Temperature
If outer emitter structures are cooled more effectively to reduce lateral far-field divergence, then far-field divergence is reduced, but device complexity increases
Solution Approach 1:
The patent segments the thermal management system into distinct zones: outer emitters receive enhanced thermal management features while inner emitters use standard design. This segmentation allows targeted intervention only where needed (at the edges), reducing lateral far-field divergence without requiring complex thermal management across the entire array, thus limiting the increase in device complexity.
Solution Approach 2:
The patent applies partial action by providing enhanced cooling only to outer emitter structures rather than uniformly to all emitters. This selective approach addresses the specific thermal deficiency of outer emitters that causes lateral far-field divergence, avoiding unnecessary complexity in regions where standard thermal management suffices.
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 adjustment significantly reduces lateral far-field divergence by ensuring uniform temperature distribution among emitter structures, enhancing the overall performance and power conversion efficiency of the laser bar.
Implementation Method 1
The inner emitter structures show a largely similar temperature profile with a uniform maximum temperature and little temperature modulation in the region between the emitter structures due to the strong thermal coupling between them
Implementation Method 2
Via the p and n contacts, charge carriers are injected into the active zone formed between the two contacts within the layer structure
Data Source
AI summary
The present invention relates to a laser bar with reduced lateral far-field divergence and, more particularly, to a laser bar with a uniform temperature profile in the lateral direction to reduce lateral far-field divergence.A laser bar (1) according to the invention comprises a plurality of emitter structures arranged in parallel next to one another in the lateral direction, wherein, for the variation of the temperature profile in lateral direction, an adjustment of the dissipated thermal power of the outer emitter structures is made with respect to the inner emitter structures enclosed by the outer emitter structures.