Semiconductor Laser Diffraction Grating Pitch Variation
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Solution Overview
Problem
The existing semiconductor laser devices face issues with defects at the boundaries of diffraction gratings, leading to inhomogeneous growth conditions and reduced luminescent efficiency due to the presence of areas without diffraction gratings, which affect the performance and efficiency of the device.
Innovation Solution
A semiconductor laser device with a first diffraction grating and a second diffraction grating continuous along the optical waveguide direction, where the second grating has a pitch 1.05 times or greater, or 0.95 times smaller than the first grating, is designed to prevent defects and maintain homogeneous growth conditions, and a manufacturing method involving continuous electron beam exposure is used to form these gratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a portion where no diffraction grating is lithographed is provided between adjacent diffraction gratings, then the diffraction grating can be formed on the wafer, but growth conditions become inhomogeneous between areas with and without diffraction grating, causing defects and degrading luminescent efficiency
Solution Approach 1:
The patent applies homogeneity by making the second diffraction grating continuous with the first diffraction grating without any gaps or portions without diffraction grating. This continuous structure ensures uniform growth conditions across the entire wafer surface, eliminating the inhomogeneity that would otherwise cause defects and degrade luminescent efficiency in the active layer.
Solution Approach 2:
The patent changes the pitch parameter of the second diffraction grating to be 1.05 times or greater, or 0.95 times or smaller of the pitch of the first diffraction grating. This parameter modification allows the second grating to have different diffraction characteristics while maintaining continuity, thus preventing defects without affecting laser oscillation wavelength.
2Reliability
If the pitch of the second diffraction grating is made different from the first diffraction grating, then defects can be prevented from spreading into the active layer, but the device structure becomes more complex
Solution Approach 1:
The patent applies local quality by making only the pitch parameter of the second diffraction grating different from the first, while keeping other structural characteristics the same. This localized modification prevents defects from spreading into the active layer without requiring complete structural redesign, thus limiting the increase in device complexity to just the pitch parameter variation.
3Reliability
If the second diffraction grating has a pitch 1.05 times or greater, or 0.95 times or smaller of the first diffraction grating, then laser oscillation wavelength is not affected, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise pitch control parameters for the second diffraction grating (1.05 times or greater, or 0.95 times or smaller of the first grating's pitch) to ensure that the laser oscillation wavelength remains unaffected. This parameter change approach maintains operational stability while establishing clear manufacturing specifications for pitch control.
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 prevents defects from spreading into the active layer, maintains uniform growth conditions, and ensures efficient laser oscillation by controlling the pitch of the second diffraction grating to avoid affecting the laser oscillation wavelength, thereby enhancing the luminescent efficiency and performance of the semiconductor laser device.
Implementation Method 1
a method for forming a diffraction grating, an electron beam exposure is known
Implementation Method 2
When a diffraction grating is formed on a wafer using the electron beam exposure
Data Source
AI summary
A semiconductor laser device having a diffraction grating is disclosed. The semiconductor laser device comprises a first diffraction grating provided on a substrate, a second diffraction grating continuous to one end of the first diffraction grating along an optical waveguide direction, and an active layer provided above the first diffraction grating. The second diffraction grating has a pitch 1.05 times or greater, or 0.95 times or smaller of the pitch of the first diffraction grating.