Surface Emitting Semiconductor Laser Higher-Order Mode Suppression
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Solution Overview
Problem
Surface emitting semiconductor lasers face challenges in maintaining fundamental transverse mode while increasing output, as larger oxidation aperture diameters induce multimode oscillation, and existing insulation films struggle to provide a sufficient difference in reflectivity between fundamental and higher-order transverse modes, leading to unstable suppression of higher-order transverse modes.
Innovation Solution
A surface emitting semiconductor laser design incorporating a higher-order transverse mode suppressing layer with a multilayer structure of insulation films, where the first, second, and third insulation films have specific refractive indices and thicknesses, optimized to transmit the oscillation wavelength, creating a distinct reflectivity difference between fundamental and higher-order transverse modes, thereby promoting fundamental mode output while suppressing higher-order modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the oxidation aperture diameter is increased to increase output, then the laser output power increases, but higher-order transverse modes are induced causing multimode oscillation
Solution Approach 1:
The patent applies local quality by creating a higher-order transverse mode suppressing layer with specific spatial distribution on the emission surface. This layer has different optical properties (refractive index and thickness) in different regions to selectively suppress higher-order modes while allowing fundamental mode to pass through, thus maintaining mode stability even with larger aperture diameters that enable higher power output.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the refractive index and thickness parameters of the insulation films in the higher-order transverse mode suppressing layer. By optimizing these parameters, the structure creates different reflectivity conditions for fundamental and higher-order transverse modes, enabling selective suppression of unwanted modes while maintaining high power output capability.
2Device complexity
If a single insulation film is used to suppress higher-order transverse modes, then the structure is simple, but the reflectivity difference between fundamental and higher-order modes is insufficient
Solution Approach 1:
The patent applies composite materials by constructing a multilayer insulation film structure where each layer has different refractive index and thickness parameters. This composite structure creates a cumulative effect that generates sufficient reflectivity difference between fundamental and higher-order transverse modes, achieving reliable mode suppression that cannot be obtained with a single insulation film layer.
Solution Approach 2:
The patent transitions from a single-layer to a multilayer structure, adding the dimension of layer stacking. This dimensional change allows for independent optimization of each layer's parameters (refractive index and thickness), creating a more effective reflectivity modulation profile across different transverse modes while maintaining manageable structural complexity.
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 effectively increases the output of fundamental transverse mode while stabilizing the suppression of higher-order transverse modes, even with larger oxidation aperture diameters, by creating a significant reflectivity difference between the two modes, enhancing the laser's performance and stability.
Implementation Method 1
the first insulation film having a first refractive index and capable of transmitting an oscillation wavelength, the second insulation film having a second refractive index and capable of transmitting the oscillation wavelength, and the third insulation film having a third refractive index and capable of transmitting the oscillation wavelength
Implementation Method 2
creating a distinct reflectivity difference between fundamental and higher-order transverse modes
Data Source
AI summary
A surface emitting semiconductor laser includes a first semiconductor multilayer reflector of a first conductivity type, an active area, a second semiconductor multilayer reflector of a second conductivity type, a current confinement layer having a conductive area and a surrounding high-resistance area, each provided on a substrate, and a higher-order transverse mode suppressing layer formed on an emission surface from which laser light is emitted and in an area in which higher-order transverse mode is induced. The higher-order transverse mode suppressing layer includes first to third insulation films having first to third refractive indices, respectively, formed on each other, and capable of transmitting an oscillation wavelength. The second refractive index is lower than the first refractive index. The third refractive index is higher than the second refractive index. The optical film thickness of the first to third insulation films is an odd number times one-fourth of the oscillation wavelength.