VCSEL DBR Reflectivity Layout for Polarization and Mode Control
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Solution Overview
Problem
Existing methods for controlling modes and polarization in VCSELs, such as reducing the oxide aperture or modifying the light emitting hole, suffer from poor reliability, reduced light output power, increased resistance, and complex processing requirements.
Innovation Solution
A semiconductor light-emitting element is designed with a substrate, multiple DBR pairs, an active layer, and metal layers, where the second DBR has a higher reflectivity than the first DBR and includes a metal diffusion layer to create different optical paths with varying reflectivities, stabilizing polarization and reducing modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the oxide aperture is decreased to control modes and stabilize polarization, then the modes are suppressed and polarization is stabilized, but the light output power is reduced and resistance of the active layer is increased
Solution Approach 1:
The patent applies local quality by creating an asymmetric DBR structure where the second DBR has higher reflectivity than the first DBR. This localized difference in reflectivity properties at specific positions (the second DBR side) enables mode control and polarization stabilization without requiring reduction of the overall light emitting aperture, thus maintaining light output power.
2Stability of the object's composition
If the oxide aperture is decreased to control modes and stabilize polarization, then the modes are suppressed and polarization is stabilized, but the resistance of the active layer is increased
Solution Approach 1:
The asymmetric DBR design with different reflectivities creates localized optical field distribution that suppresses side modes and stabilizes polarization without reducing the oxide aperture. This maintains low resistance in the active layer and preserves device reliability while achieving the desired polarization control.
3Stability of the object's composition
If the size of the light emitting hole is changed or surface grating/etch is provided to control modes and stabilize polarization, then the modes are suppressed and polarization is stabilized, but the processing becomes complex and production yield is reduced
Solution Approach 1:
The patent changes the reflectivity parameter of the DBR layers, specifically making the second DBR have higher reflectivity than the first DBR. This parameter change in the optical cavity structure achieves mode control and polarization stabilization without requiring complex processing steps such as surface grating or etch, thereby maintaining simple manufacturing processes and high production yield.
4Stability of the object's composition
If the size of the light emitting hole is changed or surface grating/etch is provided to control modes and stabilize polarization, then the modes are suppressed and polarization is stabilized, but the optical output efficiency is reduced
Solution Approach 1:
The asymmetric DBR structure creates localized differences in reflectivity that guide and confine the optical field effectively. The second DBR with higher reflectivity provides strong feedback for the lasing mode while the overall structure maintains high optical output efficiency by avoiding the energy losses associated with reduced light emitting hole sizes or surface modifications.
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 proposed solution effectively stabilizes the polarization and reduces modes in the semiconductor light-emitting element, improving reliability and optical output efficiency while simplifying the manufacturing process.
Implementation Method 1
the photons are trapped and reflected back and forth several times between the two DBRs
Implementation Method 2
two distributed Bragg reflectors (DBRs) located at two opposite sides of the active layer
Implementation Method 3
the metal diffusion layer extends and diffuses in a direction remote from the second metal layer
Data Source
AI summary
A semiconductor light-emitting element is provided, including: a substrate, a first distributed Bragg reflector (DBR), an active layer, a second DBR, a first contact layer, a second contact layer, a first metal layer and a second metal layer. The first contact layer, the first DBR, the active layer, the second DBR and the second contact layer are stacked layer by layer in a thickness direction to form a columnar structure. The semiconductor light-emitting element further includes an insulating layer at least partially covered on an outer surface of the columnar structure, and the insulating layer defines an embedding groove open in the thickness direction. A connecting portion of the second metal layer is embedded within the embedding groove and connected with the second contact layer.