Semiconductor Laser Diode Stressed Layer Thermal Lens Compensation
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Solution Overview
Problem
Semiconductor laser diodes experience a thermal lens effect due to inhomogeneous heating, leading to a refractive index profile that adversely affects beam quality by causing beam divergence.
Innovation Solution
Incorporating a stressed layer above the active layer in the semiconductor laser diode's layer sequence, which influences the refractive index profile in the waveguide layers to compensate for the inhomogeneous temperature distribution, thereby reducing the thermal lens effect and improving beam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the semiconductor laser diode operates, then the resonator generates laser output, but inhomogeneous heating occurs causing thermal lens effect that degrades beam quality
Solution Approach 1:
The stressed layer is pre-configured with specific stress and refractive index properties before operation to counteract the thermal lens effect that will occur during laser operation. The layer is designed in advance to create an opposing refractive index profile that compensates for the expected temperature distribution, thereby preventing beam quality degradation before it occurs.
Solution Approach 2:
The stressed layer modifies the refractive index distribution in the waveguide region through controlled stress and material composition. By changing the refractive index parameter spatially across the layer, the patent creates a compensating profile that offsets the thermal-induced refractive index variations, thus maintaining beam quality despite power generation.
2Object-affected harmful factors
If a stressed layer is added to compensate for thermal lens effect, then beam quality improves, but device structure becomes more complex
Solution Approach 1:
The stressed layer is integrated into the existing waveguide layer sequence, merging the compensation function with the optical guiding structure. Rather than adding a completely separate component, the stressed layer is combined with the waveguide layers to form a unified multi-layer structure that performs both light guidance and thermal lens compensation simultaneously.
Solution Approach 2:
The stressed layer serves multiple functions within the device: it provides mechanical stress to modify the refractive index profile, compensates for thermal lens effects, and maintains structural integrity of the layer sequence. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
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 stressed layer effectively compensates for the refractive index variations caused by temperature gradients, resulting in a laser beam with high beam quality and reduced divergence.
Implementation Method 1
heating of the resonator that is inhomogeneous in a lateral direction may lead to a lateral refractive index profile that brings about a lens effect that disadvantageously influences the beam quality. This effect is referred to as a thermal lens
Implementation Method 2
the stressed layer being provided for influencing a refractive index profile in the waveguide layers at least to partly compensate for an inhomogeneous variation of a refractive index in the waveguide layers, the inhomogeneous variation being brought about by an inhomogeneous temperature distribution during operation of the semiconductor laser diode
Data Source
AI summary
A semiconductor laser diode includes a layer sequence including a plurality of layers arranged one above another in a growth direction, wherein the semiconductor laser diode includes a first facet and a second facet between which a resonator extending in a longitudinal direction is formed, the layer sequence includes an active layer in which an active region is formed, the layer sequence includes waveguide layers, and the layer sequence includes a stressed layer arranged above the active layer in the growth direction, the stressed layer being provided for influencing a refractive index profile in the waveguide layers at least to partly compensate for an inhomogeneous variation of a refractive index in the waveguide layers, the inhomogeneous variation being brought about by an inhomogeneous temperature distribution during operation of the semiconductor laser diode.