Semiconductor Laser with Flared Stripe for Low Divergence
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Solution Overview
Problem
High-power semiconductor lasers with broad stripe types have highly divergent and inhomogeneous beam amplitude distributions, leading to reduced efficiency in coupling to optical fibers due to parasitic modes and 'filamentation' defects, and existing configurations are complex to produce with poor thermal dissipation.
Innovation Solution
A semiconductor laser design featuring a narrow monomode stripe with transverse index guiding transitioning into a flared part with transverse index guiding, fabricated using epitaxial growth, photolithography, etching, proton implantation, and polymer deposition, allowing for low divergence, low astigmatism, and high power emission while being easy to produce and thermally stable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a broad stripe laser configuration is used to achieve high power emission, then power output increases, but beam divergence and inhomogeneity worsen due to parasitic modes and filamentation defects
Solution Approach 1:
The laser cavity is segmented into two distinct parts: a narrow monomode stripe section for mode control and a flared amplifier section for power enhancement. This segmentation allows the narrow stripe to suppress parasitic modes and filamentation while the flared part amplifies the beam to achieve high power output, thus resolving the contradiction between power and beam quality
Solution Approach 2:
The laser structure transitions from a uniform broad stripe to a flared configuration that expands in the transverse dimension. This dimensional change allows the beam to maintain monomode characteristics in the narrow section while achieving higher power in the expanded flared section, improving beam quality without sacrificing power output
2Manufacturing precision
If a narrow stripe with flared part is implemented to improve beam homogeneity, then beam quality improves, but device complexity increases due to additional etching and regrowth steps
Solution Approach 1:
The patent merges the narrow monomode stripe and flared amplifier parts into a single continuous laser cavity formed in one epitaxial growth process. This integration eliminates the need for separate regrowth steps and reduces the number of fabrication stages, thereby improving beam homogeneity while avoiding excessive device complexity
Solution Approach 2:
Instead of creating complex three-dimensional structures through multiple regrowth steps, the invention uses a two-dimensional planar design with a flared profile that achieves the desired beam quality through geometric configuration alone, simplifying the fabrication process while maintaining beam homogeneity
3Manufacturing precision
If traditional narrow stripe laser structures are used to achieve low divergence, then beam divergence decreases, but thermal dissipation capability deteriorates
Solution Approach 1:
The laser structure is divided into a narrow stripe section for low-divergence beam generation and a wider flared section for improved thermal management. This segmentation allows the narrow section to maintain low beam divergence while the wider flared section provides enhanced surface area for heat dissipation, resolving the contradiction between beam quality and thermal performance
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 laser emits a Gaussian beam with low divergence and astigmatism, achieving power levels above 1 W, is temperature-stable, and facilitates efficient thermal dissipation, making it suitable for mass production on a single substrate with improved heat extraction.
Implementation Method 1
proton implantation through the layer of the contact, the photoresist layer preventing implantation in the zone that it covers
Implementation Method 2
epitaxial growth of the substrate and the layers of the multilayer structure
Data Source
AI summary
The present invention relates to a high-power semiconductor laser having low divergence and low astigmatism, this laser being including, in an active layer, a first part in the form of a narrow monomode stripe with transverse index guiding terminating in a second part flaring out from the first part, also with transverse index guiding.