Integrated Semiconductor Laser with Asymmetric Quantum Wells
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Solution Overview
Problem
Existing integrated semiconductor laser devices struggle to simultaneously achieve a narrow spectral linewidth and high intensity for signal light sources, which are essential for advanced optical communications, particularly in coherent communication schemes like PSK and QAM.
Innovation Solution
The integrated semiconductor laser device incorporates a semiconductor laser with a first active layer having five or fewer quantum wells and a second active layer with six or more quantum wells, where the second active layer has a longer wavelength corresponding to bandgap energy, and an optical loss unit is added between the semiconductor laser and the semiconductor optical amplifier to optimize the optical confinement factor, resulting in a device with a distributed feedback laser section and a distributed Bragg reflection section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of quantum wells in the active layer is increased to narrow the spectral linewidth, then the spectral linewidth decreases, but the optical confinement factor increases which reduces output intensity
Solution Approach 1:
The patent applies local quality by differentiating the quantum well structure between the laser section and amplifier section. The laser section uses 5 or fewer quantum wells optimized for narrow spectral linewidth, while the amplifier section uses 6 or more quantum wells optimized for high optical confinement and output intensity. This localized differentiation resolves the contradiction by allowing each section to have optimal quantum well numbers for its specific function.
Solution Approach 2:
The patent segments the semiconductor device into distinct functional sections: a laser section with a first active layer containing 5 or fewer quantum wells for generating light with narrow spectral linewidth, and an amplifier section with a second active layer containing 6 or more quantum wells for amplifying light with high optical confinement. This segmentation allows independent optimization of quantum well numbers for each function, resolving the contradiction between spectral linewidth and output intensity.
2Measurement precision
If the length of DFB laser stripes is increased to narrow the spectral linewidth, then the spectral linewidth decreases, but the device area increases
Solution Approach 1:
The patent changes the quantum well number parameter in the active layer to control spectral linewidth instead of increasing laser stripe length. By using 5 or fewer quantum wells in the laser section, the patent achieves narrow spectral linewidth (300 kHz or less) without requiring excessive laser stripe length, thereby controlling device area while meeting spectral linewidth requirements.
3Illumination intensity
If the length of semiconductor optical amplifier is increased to increase output intensity, then the output intensity increases, but the device area increases
Solution Approach 1:
The patent changes the quantum well number parameter in the amplifier section to optimize output intensity without increasing amplifier length. By using 6 or more quantum wells in the second active layer, the patent achieves high optical confinement and high output intensity (40 mW or more) with a compact amplifier structure, avoiding the need for excessive device area.
4Power
If the thickness of active layer of semiconductor optical amplifier is reduced to increase saturation optical power intensity, then the saturation optical power intensity increases, but the optical confinement factor decreases
Solution Approach 1:
The patent applies local quality by optimizing the quantum well structure specifically for the amplifier section. By using 6 or more quantum wells in the second active layer, the patent achieves both high optical confinement factor and high saturation optical power intensity, resolving the contradiction through localized structural optimization in the amplifier region.
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 enables the device to produce output laser light with a narrow spectral linewidth of 300 kHz or less and high intensity of 40 mW or more, effectively addressing the dual requirements of spectral linewidth and intensity.
Implementation Method 1
the larger the number of quantum wells in an active layer of semiconductor lasers or a semiconductor optical amplifier, the smaller the linewidth enhancement factor, resulting in a narrower spectral linewidth
Implementation Method 2
a distributed feedback laser section and a distributed Bragg reflection section
Implementation Method 3
a distributed feedback laser section and a distributed Bragg reflection section
Implementation Method 4
the semiconductor optical amplifier amplifies light output from the MMI optical coupler to output
Data Source
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AI summary
An integrated semiconductor laser device with a semiconductor laser and a semiconductor optical amplifier for amplifying output laser light of the semiconductor laser integrated on a substrate, the integrated semiconductor laser device including: a first active layer included in the semiconductor laser; and a second active layer included in the semiconductor optical amplifier, wherein the first active layer and the second active layer have a multiple quantum well structure, and the second active layer has a larger number of quantum wells than the first active layer. This provides an integrated semiconductor laser device and a semiconductor laser module whose output laser light has a narrow spectral linewidth and high intensity.