Semiconductor Laser Stripe Profile for High Output Stability
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Solution Overview
Problem
Conventional semiconductor laser devices face challenges in achieving high-output operation of 300 mW or more at high temperatures due to increased waveguide loss, which leads to heat saturation and degradation in light output efficiency, especially with longer cavity lengths, and are prone to kink formation and catastrophic optical damage.
Innovation Solution
A semiconductor laser device with a stripe portion having a region changing in width, where the effective refractive index difference between the inside and outside of the stripe portion is greater in the change region than in regions near the end faces, reducing radiation loss and waveguide loss, and stabilizing the optical axis and fundamental transverse mode oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the cavity length is increased to improve heat dissipation and enable high-output operation, then the light output capability is improved, but the waveguide loss increases causing heat saturation and degradation in light output efficiency
Solution Approach 1:
The patent applies local quality by creating a stripe portion with spatially varying width: a first region with a first width, a second region with a second width smaller than the first, and a change region connecting them. This non-uniform width distribution optimizes the effective refractive index difference locally - larger in the change region to reduce radiation loss, and smaller in the second region to maintain mode stability - thereby reducing overall waveguide loss and enabling high-output operation without heat saturation.
2Loss of energy
If the stripe width is reduced to reduce waveguide loss, then the radiation loss is reduced, but the fundamental transverse mode oscillation becomes unstable and kink formation occurs
Solution Approach 1:
The patent segments the stripe portion into three distinct regions along the cavity length: a first region with larger width, a second region with smaller width, and a change region connecting them. This segmentation allows each region to serve a specific function - the first region provides stable mode oscillation, the second region reduces radiation loss, and the change region transitions between them - thereby simultaneously achieving low radiation loss and stable fundamental transverse mode oscillation without kink formation.
3Loss of energy
If the effective refractive index difference is increased to reduce radiation loss, then the waveguide loss is reduced, but the optical axis becomes unstable and mode oscillation is affected
Solution Approach 1:
The patent applies local quality by creating spatially varying effective refractive index difference: larger in the change region to reduce radiation loss and smaller in the second region to maintain optical axis stability. The stripe width is designed to be smaller in the second region compared to the first region, which locally reduces the effective refractive index difference and prevents optical axis instability, thereby achieving low waveguide loss without compromising optical axis stability.
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 configuration enhances light output stability, reduces waveguide loss, and suppresses kink formation, allowing for high-output operation without heat saturation, thereby improving the temperature characteristic and maintaining efficient light extraction.
Implementation Method 1
a stripe portion having a region changing in stripe width, wherein an effective refractive index difference between the inside and outside of the stripe portion is greater in the stripe region changing in stripe width than in regions near end faces
Data Source
AI summary
The semiconductor laser device includes a cavity structure having a first clad layer, an active layer and a second clad layer formed on a substrate. The second clad layer has a stripe portion extending between the front end face from which laser light is extracted and the rear end face opposite to the front end face. The stripe portion has a first region located closer to the front end face, a second region located closer to the rear end face and a change region whose width changes located between the first and second regions. The effective refractive index difference between the inside and outside of the stripe portion in the change region is greater than that in the first region.