Photonic Crystal Laser Layout to Cut Scattering Loss
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Solution Overview
Problem
In photonic crystal surface emitting lasers (PCSELs), the overlap of holes forming the surface emission control photonic crystal with those of the distributed feedback control photonic crystal leads to light scattering, resulting in increased threshold values and decreased slope efficiency due to disrupted periodicity and scattering loss.
Innovation Solution
A light emitting device configuration featuring a photonic crystal layer with a first region causing in-plane resonance and a second region allowing emission in a direction different from the in-plane direction, reducing scattering loss and enabling efficient laser oscillation by separating the photonic crystal functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If holes forming the surface emission control photonic crystal are disposed between adjacent holes forming the distributed feedback control photonic crystal, then both in-plane resonance and out-of-plane emission functions are achieved, but light scattering occurs resulting in increased threshold values and decreased slope efficiency
Solution Approach 1:
The photonic crystal layer is segmented into multiple regions with different hole patterns. A first region contains holes for distributed feedback control, while a second region contains holes for surface emission control. This spatial segmentation prevents the two photonic crystal functions from interfering with each other, eliminating light scattering loss while maintaining both in-plane resonance and out-of-plane emission capabilities
Solution Approach 2:
Different regions of the photonic crystal layer are assigned different local structures and functions. The first region is optimized for distributed feedback with specific hole arrangements, while the second region is optimized for surface emission with different hole arrangements. Each region maintains its local quality without being disrupted by the other region's structure, preventing scattering loss
2Adaptability or versatility
If the two photonic crystal structures are superimposed with overlapping holes, then both distributed feedback and surface emission are controlled, but the periodicity is disrupted causing increased threshold values
Solution Approach 1:
The photonic crystal layer is divided into distinct first and second regions that do not overlap when viewed in the laminating direction. This segmentation ensures that the periodic structure of each photonic crystal region is maintained independently, preventing disruption of periodicity and avoiding increases in laser oscillation threshold values
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 configuration reduces scattering loss, inhibits threshold value increases, and enhances slope efficiency, allowing for efficient light emission and resonance with reduced speckle influence, enabling more controlled and intense light output.
Implementation Method 1
a first photonic crystal that causes light emitted by the light emitting layer to resonate in a direction orthogonal to a laminating direction of the first semiconductor layer and the light emitting layer
Implementation Method 2
a second photonic crystal that does not overlap the first region when viewed in the laminating direction and causes the light emitted by the light emitting layer to be emitted in a direction different from the orthogonal direction
Data Source
AI summary
A light emitting device including a first semiconductor layer, a second semiconductor layer, a light emitting layer disposed between the first semiconductor layer and the second semiconductor layer, and a photonic crystal layer disposed on a side of the second semiconductor layer opposite to the light emitting layer is provided. The photonic crystal layer includes a first region provided with a first photonic crystal that causes light emitted by the light emitting layer to resonate in a direction orthogonal to a laminating direction of the first semiconductor layer and the light emitting layer and does not cause the light to be emitted in a direction different from the orthogonal direction, and a second region provided with a second photonic crystal that does not overlap the first region when viewed in the laminating direction and causes the light to be emitted in a direction different from the orthogonal direction.