Sampled Grating Semiconductor Laser Diode Manufacturing
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Solution Overview
Problem
Existing semiconductor laser diodes with sampled gratings often exhibit degraded optical performance due to variations in the number or physical shape of gratings, leading to performance deviations from the designed specifications.
Innovation Solution
A method is developed to form semiconductor laser diodes with sampled gratings by alternately arranging grating and space regions along the optical axis, where the summed lengths of these regions in one combination differ from those in another, and specific semiconductor layers are epitaxially grown and etched to create diffraction gratings with varying lengths and refractive indices, ensuring precise control over grating patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of gratings in one grating region or the physical shapes of gratings vary, then the sampled grating can be formed with different structures, but the optical performance deviates from the designed specifications or degrades
Solution Approach 1:
The patent applies preliminary action by pre-forming multiple combinations of grating regions and space regions with different grating counts during the manufacturing process. This allows the desired combination to be selected before final device assembly, ensuring optimal optical performance is achieved through pre-planned structural variations rather than post-manufacturing adjustments.
Solution Approach 2:
The patent utilizes parameter changes by varying the number of gratings in different grating regions while maintaining the same summed length for grating and space regions. This parameter variation allows exploration of different structural configurations to optimize optical performance without changing the overall device dimensions, thereby resolving the contradiction between structural adaptability and performance consistency.
2Length of stationary object
If the grating region and space region have fixed summed length across all combinations, then the overall device size remains consistent, but the individual grating region lengths must vary to achieve different optical characteristics
Solution Approach 1:
The patent applies segmentation by dividing the optical path into multiple grating regions and space regions that can be independently configured. Each combination maintains the same total length but distributes it differently among grating and space regions, allowing structural complexity to be managed through modular segmentation while preserving overall device compactness.
Solution Approach 2:
The patent employs asymmetry by creating grating region and space region combinations where the individual lengths are unequal and vary between combinations, even though the summed length remains constant. This asymmetric distribution enables different optical characteristics to be achieved within a consistent device footprint, balancing length consistency with structural diversity.
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 approach enhances the optical performance of semiconductor laser diodes by ensuring consistent and desired grating patterns, improving the emission characteristics and reducing performance degradation, thereby achieving better tunability and stability.
Implementation Method 1
etching at least the second the semiconductor layer by using the first photoresist as an etching mask
Implementation Method 2
The third layer processed in step (8) has refractive index substantially same with refractive index of the first semiconductor layer but different from refractive index of the second semiconductor layer. The etched second semiconductor layers are isolated by the first and third semiconductor layers.
Data Source
AI summary
A method to produce a semiconductor laser diode (LD) including a sampled grating (SG) is disclosed. The method prepares various resist patterns each including grating regions and space regions alternately arranged along an optical axis. The grating regions and the space region in respective cavity types have total widths same with the others but the grating regions in respective types has widths different from others. After the formation of the grating patterns based on the resist patterns, only one of the grating patterns is used for subsequent processes.