Semiconductor Laser Stabilization via Sampled Grating Segmentation
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Solution Overview
Problem
The semiconductor laser experiences unstable oscillation modes due to uneven carrier density caused by spatial hole burning effects, leading to increased optical intensity at the center of the resonator, which affects the wavelength selection and stability of the laser.
Innovation Solution
A semiconductor laser design incorporating a first reflector with a sampled grating having short-segment and long-segment regions, where the long-segment region has an optical length larger than the short-segment region by an integral multiple plus-minus 25%, and is positioned closer to the second reflector, stabilizes the oscillation mode by flattening the optical intensity distribution and enhancing interference effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sampled grating with uniform segments is used in the semiconductor laser, then the wavelength selection function is achieved, but the optical intensity becomes concentrated at the center of the resonator causing spatial hole burning effect and unstable oscillation mode
Solution Approach 1:
The patent applies local quality by making the segment lengths non-uniform, specifically creating a long-segment region with optical length larger than short-segment regions by an integral multiple plus-minus 25%. This local variation in segment length redistributes the optical intensity distribution along the resonator, preventing concentration at the center and reducing spatial hole burning effect while maintaining wavelength selection capability.
2Stability of the object's composition
If the optical length of segments is made non-uniform to reduce spatial hole burning, then oscillation mode stability is improved, but the wavelength selection precision may be affected
Solution Approach 1:
The patent applies parameter changes by carefully controlling the optical length of segments within a specific range (integral multiple plus-minus 25%). This controlled variation in segment length parameters achieves redistribution of optical intensity to stabilize oscillation mode, while the precise control within the specified range maintains the wavelength selection precision.
3Stability of the object's composition
If a long-segment region is positioned closer to the second reflector, then the optical intensity distribution is flattened effectively, but the device structure becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the sampled grating into multiple segments with different length characteristics (short-segment regions and long-segment region). This segmentation allows strategic placement of the long-segment region closer to the second reflector to effectively flatten optical intensity distribution, while the modular segmented structure makes the complexity manageable through systematic design.
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 design stabilizes the oscillation mode by reducing optical intensity variations and carrier density unevenness, achieving a more stable and efficient wavelength selection process.
Implementation Method 1
a first reflector that is provided in a gain region and has a sampled grating in which a plurality of segments are combined, the segment having a diffraction grating region and a space region next to the diffraction grating
Implementation Method 2
enhancing interference effects
Implementation Method 3
an optical waveguide layer that is made of Ga0.22In0.78As0.47P0.53
Data Source
AI summary
A semiconductor laser includes: a first reflector that is provided in a gain region and has a sampled grating in which a plurality of segments are combined; and a second reflector that is optically connected to the first reflector and has a sampled grating in which a plurality of segments are combined, the plurality of segments of the first reflector having a short-segment region and a long-segment region, the long-segment region having an optical length that is larger than that of the short-segment region and being positioned closer to the second reflector than at least one of the short-segment region, the optical length of the long-segment region being larger than that of the short-segment region in a range of integral multiple (n≧1) plus-minus 25% of the optical length of the short-segment.