PCSEL Multi-Ring Structure for Stable Single-Mode Oscillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Photonic-crystal surface emitting lasers (PCSELs) face challenges in operating in a single mode due to higher order modes being excited, which is attributed to uneven carrier density distribution, with higher density near the periphery leading to difficulty in achieving stable single-mode oscillation.
Innovation Solution
The PCSEL design incorporates a multi-ring structure in the second semiconductor layer with varying ring widths, particularly narrower rings towards the periphery, and a second electrode covering these rings, creating a higher carrier density at the center and lower density towards the periphery, thereby suppressing higher order modes and promoting fundamental mode oscillation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional PCSEL structure is used, then the device is simple to manufacture, but higher order modes are excited making single-mode operation difficult
Solution Approach 1:
The second semiconductor layer is designed with spatially varying properties: a first region with higher carrier density near the center and second regions with lower carrier density towards the periphery. This local quality variation suppresses higher order modes while maintaining fundamental mode oscillation, resolving the contradiction between single-mode stability and structural simplicity.
Solution Approach 2:
The second semiconductor layer is segmented into multiple regions with different carrier density characteristics. The layer is divided into a central first region and peripheral second regions, allowing independent optimization of carrier distribution to achieve single-mode operation without excessive structural complexity.
2Reliability
If carrier density is uniformly distributed, then the structure is simple, but higher order modes are excited due to peripheral carrier accumulation
Solution Approach 1:
The carrier density distribution is made non-uniform with specific local characteristics: higher density in the central first region and lower density in the peripheral second regions. This local quality control prevents peripheral carrier accumulation that excites higher order modes, achieving reliable mode control.
Solution Approach 2:
The carrier density parameter is varied spatially across the second semiconductor layer. By changing the carrier density from the center towards the periphery, the patent achieves better mode control while avoiding the complexity of completely uniform 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 effectively suppresses higher order modes and enhances the likelihood of single-mode oscillation by optimizing carrier density distribution, allowing for stable operation in the fundamental mode with increased light output.
Implementation Method 1
a photonic crystal layer stacked under the active layer, wherein the photonic crystal layer has a first region and a plurality of second regions each having a refractive index different from a refractive index of the first region
Implementation Method 2
The second semiconductor layer has a plurality of ring portions. The plurality of ring portions form a multi-ring structure. A carrier density becomes higher near a center of the multi-ring structure and becomes lower near an outer periphery
Data Source
AI summary
A photonic-crystal surface emitting laser includes a first semiconductor layer, an active layer stacked on the first semiconductor layer, a photonic crystal layer stacked on or under the active layer, a second semiconductor layer provided opposite to the first semiconductor layer with respect to the active layer, a first electrode electrically connected to the first semiconductor layer, and a second electrode electrically connected to the second semiconductor layer. The photonic crystal layer has a first region and a plurality of second regions each having a refractive index different from a refractive index of the first region. The second semiconductor layer has a plurality of ring portions. The plurality of ring portions form a multi-ring structure.