Broad-Area Semiconductor Laser Narrow Lateral Beam Divergence
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Solution Overview
Problem
Current semiconductor laser structures face challenges in achieving narrow lateral beam divergence, leading to increased thermal resistance and limited maximum optical power, particularly in high-power lasers, due to the limitations of gain-guided and index-guided structures.
Innovation Solution
A broad-area semiconductor laser structure is developed that combines gain-guiding and index-guiding, with a wider index-guided stripe compared to the gain-guided stripe, achieving significant narrowing of the lateral divergence of the optical output beam and improved thermal design for efficient heat removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If gain-guided structure is used, then ease of manufacture is improved, but lateral beam divergence increases
Solution Approach 1:
The patent combines gain-guiding and index-guiding structures into a single laser device. The gain-guided stripe provides ease of manufacture through simple current injection, while the index-guided stripe with wider confinement region provides narrow lateral beam divergence through refractive index profiling, achieving both benefits simultaneously.
Solution Approach 2:
The patent uses a composite structure with different epitaxial layers having different refractive indices. The index-guided stripe is formed by selective modification of refractive index in specific layers, creating a composite optical structure that provides lateral confinement while maintaining manufacturing simplicity.
2Shape
If index-guided structure is used, then lateral beam divergence decreases, but device complexity increases
Solution Approach 1:
The patent divides the laser structure into distinct functional regions: a gain-guided stripe for current injection and an index-guided stripe for optical confinement. The index-guided stripe is further segmented into specific epitaxial layers with modified refractive indices, allowing narrow beam divergence while maintaining manageable device complexity through functional separation.
Solution Approach 2:
The patent applies refractive index modification only in specific regions (the index-guided stripe) and specific layers, rather than throughout the entire device. This localized modification provides the necessary optical confinement while minimizing the overall complexity of the device structure.
3Illumination intensity
If narrow lateral beam divergence is achieved, then optical power concentration improves, but thermal resistance increases
Solution Approach 1:
The patent separates the optical confinement function (lateral dimension) from the thermal management function (vertical dimension). The index-guided stripe provides lateral confinement for narrow beam divergence, while the vertical layer structure with thermal conduction paths manages heat removal, allowing optical power concentration without excessive thermal resistance.
Solution Approach 2:
The patent segments the device into distinct functional layers that can be optimized independently for optical performance and thermal management. The index-guided stripe and confining layers are designed for optical confinement, while the substrate and heat sink structures are optimized for thermal conduction, resolving the contradiction between optical concentration and thermal 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
The combination of gain-guiding and index-guiding results in a narrower lateral divergence angle and increased maximum optical power, effectively addressing the thermal limitations of existing structures by enhancing heat removal capabilities.
Implementation Method 1
an active layer for providing optical gain
Implementation Method 2
a sequence of epitaxial layers is deposited to form an optical waveguide with a perpendicular index profile for guiding an optical beam in a vertical direction
Implementation Method 3
an index guiding region for providing optical confinement in a lateral direction
Data Source
AI summary
The invention relates to high power broad-area semiconductor lasers incorporating a structure that provides both gain guiding and index guiding. The lateral width of the index guiding region is greater than the lateral width of the gain guiding region by at least 20 micron. This results in a high power broad-area semiconductor laser which has reduced lateral divergence of the output beam.