Photonic-crystal surface emitting laser and method of manufacturing the same
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Solution Overview
Problem
Existing photonic-crystal surface emitting lasers face reduced optical output due to light scattering and reflection losses at the electrode surfaces, which limits their efficiency.
Innovation Solution
A photonic-crystal surface emitting laser design that includes a photonic crystal layer with varying refractive indices and an insulating film with openings, where the second electrode is connected to the semiconductor layer through these openings, reducing contact area and minimizing surface roughening, thereby enhancing reflectivity and adjusting light phase for increased optical output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second electrode is directly contacted with the second semiconductor layer, then electrical connection is achieved, but the contact area causes surface roughening and reduces reflectivity
Solution Approach 1:
An insulating film with openings is introduced as an intermediary between the second electrode and the second semiconductor layer. This mediator allows electrical connection through the openings while the insulating portions maintain a smooth reflective surface, preventing direct contact that would cause roughening and reflectivity loss.
2Reliability
If the electrode surface area is increased, then electrical connection is improved, but light scattering increases and optical output decreases
Solution Approach 1:
The electrode contact area is segmented into discrete openings in the insulating film rather than a continuous large-area contact. This segmentation allows sufficient electrical connection through multiple openings while minimizing the total surface area that could scatter light, thus reducing light scattering harmful effects.
3Loss of energy
If the contact area between electrode and semiconductor layer is reduced, then reflectivity is improved, but electrical connection may be compromised
Solution Approach 1:
The insulating film structure creates local quality variations: openings provide localized electrical connection points with sufficient area for reliable contact, while the surrounding insulating portions maintain smooth reflective surfaces. This local differentiation simultaneously achieves both reduced overall contact area for higher reflectivity and adequate local contact areas for reliable electrical connection.
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
The design increases optical output by improving reflectivity and reducing scattering, achieving higher slope efficiency and optical power output compared to conventional designs.
Implementation Method 1
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 electrode is electrically connected to the second semiconductor layer at the plurality of openings
Data Source
AI summary
A photonic-crystal surface emitting laser includes a first semiconductor layer, an active layer stacked over the first semiconductor layer, a second semiconductor layer provided opposite to the first semiconductor layer with respect to the active layer, a photonic crystal layer provided between the first semiconductor layer and the second semiconductor layer, a first electrode electrically connected to the first semiconductor layer, an insulating film provided on a surface of the second semiconductor layer opposite to the active layer, and a second electrode provided at a surface of the insulating film opposite 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 insulating film has a plurality of openings. The second electrode is electrically connected to the second semiconductor layer at the plurality of openings.