Long Resonator Surface Emitting Laser with GaInP Contact Layer
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Solution Overview
Problem
Surface emitting semiconductor lasers face challenges in achieving long life and high light output while maintaining resistance to Electro Static Discharge (ESD) and reducing heat emission, as decreasing the oxidization aperture diameter increases resistance and shortens the device's life, and increasing the resonator length leads to increased optical loss between transverse modes.
Innovation Solution
A surface emitting semiconductor laser with a long resonator structure is designed, featuring a semi-insulating i-type AlGaAs layer and a contact layer made of n-type GaInP, which suppresses the formation of deep impurity levels and crystalline defects, allowing for increased resonator length and oxidization aperture diameter, thereby enhancing light output and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the resonator length is increased to enhance light output, then the light output is improved, but the optical loss between transverse modes increases
Solution Approach 1:
The patent applies local quality by creating a long resonator cavity with specific local structures including distributed Bragg reflectors at the ends and a quantum well active region in the center. This localized structuring allows the resonator to maintain high Q-factor and reduce optical loss while achieving extended length for enhanced light output.
Solution Approach 2:
The patent employs composite materials by combining GaAs substrate with AlGaAs distributed Bragg reflector layers of alternating high and low refractive indices, and InGaAs quantum well active regions. This composite structure enables the long resonator to achieve both extended length and reduced optical loss through optimized material properties.
2Reliability
If the oxidization aperture diameter is decreased to improve ESD resistance, then the ESD resistance is improved, but the device life is shortened due to increased resistance
Solution Approach 1:
The patent applies parameter changes by optimizing the oxidization aperture diameter to a specific range that balances ESD resistance and device life. Additionally, the Al composition ratio in the AlGaAs layer is adjusted to control deep level formation, thereby improving reliability without sacrificing device longevity.
3Stability of the object's composition
If the Al composition ratio in AlGaAs is increased to suppress deep level formation, then the crystalline defect formation is reduced, but the lattice matching with substrate becomes more difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Al composition ratio in the AlGaAs layer to fall within a specific range. This optimization simultaneously achieves suppression of deep level formation and maintenance of lattice matching with the GaAs substrate, resolving the contradiction between crystalline stability and manufacturability.
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 achieves high light output up to 5 mW and extends the device's life by suppressing crystalline defects and reducing ESD resistance, while maintaining single transverse mode operation and minimizing longitudinal mode switching.
Implementation Method 1
a first distributed Bragg reflector, a second distributed Bragg reflector, and a resonant cavity are formed on a GaAs substrate in this order
Implementation Method 2
a resonant cavity which has an optical film thickness of 10 to 20 times an oscillation wavelength
Implementation Method 3
an InGaAs quantum well active region... which has a conduction band minimum at a Γ point
Implementation Method 4
an InGaAs quantum well active region... in which a ground state and a first excited state are separated from each other by 30 meV or more
Implementation Method 5
a contact layer which is made of n-type GaInP and has a film thickness of not less than an oscillation wavelength... suppresses the formation of deep impurity levels and crystalline defects
Implementation Method 6
allowing for increased resonator length and oxidization aperture diameter, thereby enhancing light output and reliability... maintaining single transverse mode operation
Data Source
AI summary
A surface emitting semiconductor laser includes a substrate, a first semiconductor multi-layer reflector formed on the substrate and including a pair of a high refractive index layer having a relatively high refractive index and a low refractive index layer having a relatively low refractive index which are laminated, a semi-insulating i type AlGaAs layer formed on the first semiconductor multi-layer reflector, an n type semiconductor layer formed on the AlGaAs layer, an active region formed on the semiconductor layer, a p type second semiconductor multi-layer reflector formed on the active region and including a pair of a high refractive index layer having a relatively high refractive index and a low refractive index layer having a relatively low refractive index which are laminated, an n side first electrode electrically connected to the semiconductor layer, and a p side second electrode electrically connected to the second semiconductor multi-layer reflector.