Photonic Crystal Surface-Emitting Laser With Current Blocking Region
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Solution Overview
Problem
Current photonic crystal surface-emitting lasers (PCSELs) face issues with current leakage outside the light extraction portion, which deteriorates their characteristics, such as increased threshold current and reduced optical power output.
Innovation Solution
The design incorporates a current blocking region with a photonic crystal layer having a different refractive index, strategically arranged to suppress current leakage by forming a thyristor structure and using insulated layers, thereby concentrating current flow within the light emitting region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photonic crystal surface-emitting laser is designed with a light emitting region, then light emission is achieved, but current leakage occurs outside the light extraction portion which deteriorates device characteristics
Solution Approach 1:
The device is divided into distinct functional regions: a light emitting region for light extraction and a current blocking region for confining current. This segmentation prevents current leakage by spatially separating current conduction and light emission functions, thereby improving device characteristics while maintaining efficient light output.
Solution Approach 2:
Different regions of the photonic crystal layer are assigned different properties: the light emitting region has optimized photonic crystal structures for light extraction, while the current blocking region has modified structures (such as filled holes or different material composition) that create potential barriers to current flow. This local differentiation allows simultaneous optimization of light emission and current confinement.
2Reliability
If current blocking structures are added to suppress current leakage, then current confinement is improved, but device structure becomes more complex
Solution Approach 1:
The photonic crystal layer serves multiple functions: it provides the photonic bandgap structure for light emission in the light emitting region, and simultaneously acts as a current blocking structure in the current blocking region through modified hole patterns or material filling. This multi-functionality reduces the need for separate current blocking layers, thereby limiting the increase in device complexity.
Solution Approach 2:
The current blocking function is merged with the photonic crystal structure by modifying the hole pattern or filling specific regions of the photonic crystal layer. This integration eliminates the need for separate current blocking layers in some implementations, reducing overall device complexity while maintaining effective current confinement.
3Loss of energy
If the photonic crystal layer structure is modified to block current, then current leakage is reduced, but light emission efficiency may be affected
Solution Approach 1:
The photonic crystal layer exhibits spatially varying properties: in the light emitting region, the hole pattern is optimized for light extraction efficiency, while in the current blocking region, the holes are filled or modified to create current barriers. This local differentiation ensures that current blocking modifications do not negatively impact light emission efficiency in the light emitting region.
Solution Approach 2:
The photonic crystal layer is segmented into functionally distinct zones that can be independently optimized. The light emitting region maintains the original photonic crystal structure for efficient light extraction, while the current blocking region uses modified structures. This segmentation allows simultaneous optimization of both current confinement and light emission efficiency without mutual interference.
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 approach enhances the characteristics of PCSELs by reducing threshold current, increasing optical power, and enabling high-speed modulation with reduced parasitic capacitance.
Implementation Method 1
The photonic crystal functions as a diffraction grating to reflect and diffract light
Implementation Method 2
a photonic crystal and an active layer having an optical gain are stacked
Implementation Method 3
an active layer having an optical gain
Data Source
AI summary
A photonic crystal surface-emitting laser includes a light emitting region from which light is emitted in a direction crossing an in-plane direction, and a current blocking region that is adjacent to the light emitting region in the in-plane direction and in which current is less likely to flow than in the light emitting region. The light emitting region and the current blocking region each include a photonic crystal layer. The photonic crystal layer has a first region and second regions periodically arranged in the first region. A refractive index of each of the second regions is different from that of the first region. The light emitting region includes a first semiconductor layer, an active layer, and a second semiconductor layer. The first semiconductor layer, the active layer, and the second semiconductor layer are sequentially stacked on top of one another in an emission direction of the light.