VCSEL Current Confinement Layers for Mode Selectivity
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Solution Overview
Problem
Existing VCSELs face challenges in selectively suppressing high-order transverse mode oscillation while maintaining efficient light output, as thick current confinement layers lead to light loss and reduced basic transverse mode output.
Innovation Solution
A VCSEL design featuring a first current confinement layer at an antinode with a larger diameter and a second current confinement layer at a node, both with specific thicknesses and diameters, to confine current uniformly and minimize light loss, allowing selective suppression of high-order transverse mode oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the current confinement layer is made thick to confine current uniformly and decrease resistance, then electrical power consumption is lowered, but light loss increases and basic transverse mode output is reduced
Solution Approach 1:
The current confinement structure is divided into multiple separate current confinement layers positioned at different locations within the resonator. Each layer has optimized thickness to perform specific functions: confining current while minimizing light absorption, thereby resolving the contradiction between uniform current confinement and light loss reduction.
Solution Approach 2:
Different regions of the current confinement layers are designed with different properties: the layers are positioned to have high current confinement capability in the central region while being transparent to light in the light emission path. This local differentiation allows simultaneous achievement of uniform current distribution and low light loss.
2Power
If the light emitting aperture is widened to obtain high output, then light output increases, but high-order transverse mode oscillation is also generated at high output
Solution Approach 1:
The current confinement layers are strategically positioned and sized to create non-uniform current density distribution: high current density in the central region to support basic transverse mode oscillation, and reduced current density at the edges to suppress high-order transverse mode oscillation. This allows the light emitting aperture to be widened for high output while maintaining mode stability.
3Use of energy by moving object
If a single current confinement layer with large diameter is used to decrease resistance, then electrical power consumption is lowered, but high-order transverse mode oscillation cannot be selectively suppressed
Solution Approach 1:
Instead of using a single current confinement layer, the invention employs multiple current confinement layers with different diameters and positions. The combination of these layers achieves both low resistance (through sufficient current confinement area) and selective suppression of high-order transverse modes (through appropriate spatial distribution of current density).
Solution Approach 2:
The problem is solved by adding the dimensional aspect of vertical layering within the resonator. Multiple current confinement layers are positioned at different heights, creating a three-dimensional current confinement structure that provides both low resistance and mode selectivity, which cannot be achieved with a single planar layer.
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 design enables intense current injection into the central light emitting region, suppressing high-order transverse mode oscillation while maintaining low light loss and improving basic transverse mode output, thereby reducing electrical power consumption and increasing light output.
Implementation Method 1
a resonator including an active layer having a light emitting region and a pair of a first multilayer reflector and a second multilayer reflector provided with the active layer in between, the resonator resonating in a given wavelength
Implementation Method 2
a first current confinement layer having a first current injection region in a region corresponding to the light emitting region, and being formed at a region between the active layer and the first multilayer reflector
Data Source
AI summary
A VCSEL which can be easily manufactured and can selectively suppress only high-order transverse mode oscillation is provided. The VCSEL includes a resonator, a first current confinement layer, and a second current confinement layer. The resonator includes an active layer having a light emitting region, and a pair of first multilayer reflector and a second multilayer reflector provided with the active layer in between, and resonate is generated in a given wavelength. The first current confinement layer has a current injection region is a region corresponding to the light emitting region, and is formed at a region including an antinode of a standing wave. The second current confinement layer has a current injection region with a diameter smaller than a diameter of the first current injection region and is formed at a region including a node standing wave.