VCSEL Transverse Mode Control via Segmented Reflectance
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Solution Overview
Problem
Existing Vertical Cavity Surface Emitting Lasers (VCSELs) face challenges in achieving high output of the fundamental transverse mode while preventing oscillation of the high-order transverse mode, as previous methods often inadvertently suppress the fundamental mode's output in the process.
Innovation Solution
A VCSEL design featuring a transverse mode adjustment section with high and low reflectance areas, where the high reflectance area is positioned in a region opposing the center of the current injection region and the low reflectance area is positioned elsewhere, effectively reducing the gain of high-order transverse modes while minimizing the impact on the fundamental mode's gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflectance adjustment layer is provided in the central part of the light emitting aperture to prevent high-order transverse mode oscillation, then high-order mode oscillation is suppressed, but the fundamental transverse mode output is reduced
Solution Approach 1:
The light emitting aperture is divided into multiple regions with different reflectance characteristics: a first region (central part) with high reflectance to suppress high-order modes, and a second region (peripheral part) with low reflectance to maintain fundamental mode output. This spatial segmentation allows simultaneous optimization of mode control and output power.
Solution Approach 2:
Different regions of the light emitting aperture are assigned different optical properties (reflectance values) according to their functional requirements. The central region has high reflectance for mode control, while the peripheral region has low reflectance for power output, creating local quality variations that resolve the contradiction.
2Power
If the light emitting aperture is enlarged to increase fundamental mode output, then output power increases, but high-order transverse mode oscillation becomes more likely
Solution Approach 1:
The enlarged light emitting aperture is segmented into regions with different reflectance characteristics. The peripheral region with low reflectance allows the aperture to be enlarged for higher power output, while the central region with high reflectance maintains mode stability by suppressing high-order modes.
Solution Approach 2:
The problem is solved by transitioning from a uniform reflectance design to a spatially varying reflectance distribution across the aperture plane. This dimensional approach allows independent optimization of power output (aperture size) and mode stability (reflectance distribution).
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 allows for high output of the fundamental transverse mode while significantly reducing the oscillation of high-order transverse modes, maintaining a high light output and maintaining the fundamental mode's characteristics.
Implementation Method 1
The transverse mode adjustment section has a high reflectance area and a low reflectance area. The high reflectance area is formed in a region including a first opposed region opposing to a center point of the current injection region
Data Source
AI summary
A Vertical Cavity Surface Emitting Laser (VCSEL) capable of providing high output of fundamental transverse mode while preventing oscillation of high-order transverse mode is provided. The VCSEL includes a semiconductor layer including an active layer and a current confinement layer, and a transverse mode adjustment section formed on the semiconductor layer. The current confinement layer has a current injection region and a current confinement region. The transverse mode adjustment section has a high reflectance area and a low reflectance area. The high reflectance area is formed in a region including a first opposed region opposing to a center point of the current injection region. A center point of the high reflectance area is arranged in a region different from the first opposed region. The low reflectance area is formed in a region where the high reflectance area is not formed, in an opposed region opposing to the current injection region.