Edge-Emitting Semiconductor Laser Thin Waveguide Beam Profile
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Solution Overview
Problem
Conventional nitride compound semiconductor lasers face challenges in achieving precise control over output power, particularly at low powers, due to high current gradients and elliptical beam profiles, which require complex and expensive optical systems.
Innovation Solution
An edge-emitting semiconductor laser with a thin waveguide region (≤400 nm) and high reflectivity at the side facets, reducing emission angle differences and enabling a circular beam profile with cost-effective spherical lenses, while maintaining low threshold current intensity and small output power gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the waveguide region is made wide to achieve high efficiency at high optical powers, then the emission angle parallel to the layer plane becomes small, but the emission angle perpendicular to the layer plane becomes large due to diffraction, resulting in a highly elliptic laser beam
Solution Approach 1:
The patent applies parameter changes by reducing the waveguide region thickness to 400 nm or less, which fundamentally alters the diffraction characteristics. This thickness parameter modification balances the emission angles in both directions, transforming the highly elliptic beam profile into a more circular shape while maintaining high power efficiency
2Shape
If the waveguide region thickness is reduced to achieve a circular beam profile, then the emission angle difference between horizontal and vertical directions is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs thin film technology by creating a waveguide region with thickness of 400 nm or less using epitaxial growth methods. This thin film approach enables precise thickness control through standardized semiconductor fabrication processes, achieving the required beam circularity while managing manufacturing precision through established industrial techniques
3Power
If conventional wide waveguide structures are used, then high optical power efficiency is achieved, but a complicated and expensive optical system is required to correct the elliptic beam profile
Solution Approach 1:
The patent extracts the beam shaping function from external optical components and integrates it directly into the waveguide structure itself. By designing the waveguide with thickness of 400 nm or less, the desired circular beam profile is achieved inherently at the source, eliminating the need for complicated external optical correction systems
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 design achieves stable operation at low output powers with precise control over optical output, reducing production costs and eliminating the need for complex optical systems, suitable for applications like laser pointers.
Implementation Method 1
a first waveguide layer, a second waveguide layer and an active layer arranged between the first waveguide layer and the second waveguide layer
Implementation Method 2
a semiconductor laser of this type typically has a comparatively large emission angle in a direction perpendicular to the epitaxial layers on account of the diffraction
Data Source
AI summary
The invention relates to an edge-emitting semiconductor laser comprising a semiconductor body (10), which comprises a waveguide region (4), wherein the waveguide region (4) comprises a first waveguide layer (2A), a second waveguide layer (2B) and an active layer (3) arranged between the first waveguide layer (2A) and the second waveguide layer (2B) and serving for generating laser radiation (5), and the waveguide region (4) is arranged between a first cladding layer (1A) and a second cladding layer (1B) disposed downstream of the waveguide region (4) in the growth direction of the semiconductor body (10). The waveguide region (4) has a thickness d of 400 nm or less, and an emission angle of the laser radiation (5) emerging from the semiconductor body (10) in a direction parallel to the layer plane of the active layer (3) and the emission angle of the laser radiation (5) emerging from the semiconductor body (10) in a direction perpendicular to the layer plane of the active layer (3) differ from one another by less than a factor of 3.