Distributed-Feedback Semiconductor Laser Trench Grating Heat Dissipation
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Solution Overview
Problem
Distributed feedback semiconductor lasers face challenges in heat dissipation and current confinement, particularly in the lateral direction, which affects their performance and efficiency, especially for wavelengths between 2 to 100 µm.
Innovation Solution
The design incorporates a semiconductor stacked body with a trench portion acting as a distributed reflector, providing improved heat dissipation and optical confinement without the need for complex epitaxial regrowth processes, by arranging the trench portions on the sides of the active region and using a dielectric layer to enhance the distributed feedback effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ridge cross section is used to improve current confinement and optical confinement, then current confinement is possible and optical confinement effect increases, but heat dissipation in the lateral direction from the active layer is insufficient
Solution Approach 1:
The patent introduces trench portions that divide the semiconductor stacked body into distinct regions, creating a segmented structure. These trenches separate the active layer from the cladding layers laterally, forming current confinement regions while simultaneously creating heat dissipation pathways. The segmentation allows independent optimization of current confinement and heat dissipation functions.
Solution Approach 2:
The patent adds vertical dimensionality by introducing trenches that extend through the thickness of the semiconductor stacked body. This creates a three-dimensional structure where heat can dissipate in multiple directions (laterally through the trenches and vertically through the substrate), rather than being confined to a single planar ridge structure.
2Device complexity
If a stripe electrode is provided on a semiconductor stacked body to simplify the structure, then the structure is simpler, but current confinement is insufficient and optical confinement effect is small
Solution Approach 1:
The patent introduces trench portions filled with dielectric material as an intermediary structure between the stripe electrode and the active layer. This dielectric filling in the trenches acts as a mediator that enhances current confinement by creating a potential barrier, while the overall structure remains relatively simple and compatible with standard fabrication processes.
3Reliability
If epitaxial regrowth processes are used to create distributed feedback gratings, then single-mode laser operation is achieved, but the manufacturing process becomes complex
Solution Approach 1:
Instead of creating the distributed feedback grating through complex epitaxial regrowth processes during semiconductor layer formation, the patent inverts the approach by forming the grating structure through subsequent processing steps such as etching and filling. This allows the grating to be created after the basic semiconductor structure is already in place, significantly simplifying the manufacturing process while maintaining single-mode laser operation.
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 heat dissipation and maintains optical confinement, reducing thermal resistance and preventing catastrophic optical damage, while simplifying the manufacturing process and reducing costs.
Implementation Method 1
a diffraction grating is provided along the optical axis
Implementation Method 2
distributed feedback semiconductor laser in which a diffraction grating is provided
Implementation Method 3
an active layer 24 that is provided on the first layer 22 and is configured to emit laser light
Implementation Method 4
the optical confinement effect in the lateral direction is small
Data Source
Figure 1A~1D
Figure 2
Figure 3A~3C
AI summary
A distributed feedback semiconductor laser of includes a semiconductor stacked body and a first electrode. The semiconductor stacked body includes a first layer, an active layer that is provided on the first layer and is configured to emit laser light by an intersubband optical transition, and a second layer that is provided on the active layer. The semiconductor stacked body has a first surface including a flat portion and a trench portion; the flat portion includes a front surface of the second layer; the trench portion reaches the first layer from the front surface; the flat portion includes a first region and a second region; the first region extends along a first straight line; the second region extends to be orthogonal to the first straight line; and the trench portion and the second region outside the first region form a diffraction grating having a prescribed pitch along the first straight line. The first electrode is provided in the first region.