Nitride Surface Emitter Resonance Layer for Higher Optical Confinement
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Solution Overview
Problem
Surface emitting light-emitting devices using nitride semiconductors face challenges in achieving a high optical confinement coefficient for resonant modes, leading to increased threshold current values and reduced stability of oscillation, particularly in the ultraviolet to blue region.
Innovation Solution
Incorporating a high refractive index layer with a superlattice structure between the cladding layers and the resonance mode formation layer, which includes a photonic crystal layer with modified refractive index regions, to enhance the optical confinement coefficient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a resonance mode formation layer is provided in a surface emitting light-emitting device to achieve laser output, then the device can emit laser light in a direction intersecting with the substrate main surface, but the optical confinement coefficient in the resonance mode formation layer is insufficient (20% or less), resulting in increased threshold current values
Solution Approach 1:
A high refractive index layer is introduced as an intermediary between the resonance mode formation layer and the cladding layers. This intermediate layer has a refractive index higher than both the resonance mode formation layer and cladding layers, creating enhanced optical confinement for the resonance mode without requiring the resonance mode formation layer itself to have high confinement properties, thereby reducing threshold current
Solution Approach 2:
The patent employs a composite layered structure combining multiple materials with different refractive indices: the resonance mode formation layer (with periodic refractive index modulation), the high refractive index layer (with refractive index higher than surrounding layers), and cladding layers. This composite structure achieves superior optical confinement by leveraging the refractive index contrast among different material layers
2Reliability
If a resonance mode formation layer with periodic refractive index structure is used to form resonant modes, then laser oscillation can be achieved, but the oscillation stability is insufficient
Solution Approach 1:
The high refractive index layer acts as a mediator that provides additional optical confinement and stabilizes the resonance mode. By positioning this layer adjacent to the resonance mode formation layer, it enhances the modal stability and reduces oscillation instability without altering the fundamental periodic structure of the resonance mode formation layer
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 significantly improves the optical confinement coefficient, reducing the threshold current and enhancing the stability of the oscillation mode in nitride semiconductor-based surface emitting devices.
Implementation Method 1
the high refractive index layer has a refractive index higher than that of any of the first cladding layer, the second cladding layer, and the resonance mode formation layer
Implementation Method 2
The resonance mode formation layer includes a base layer and a plurality of modified refractive index regions having a refractive index different from a refractive index of the base layer and distributed two-dimensionally
Data Source
AI summary
A light-emitting device according to an embodiment includes a structure for increasing an optical confinement coefficient of a layer forming a resonance mode. The light-emitting device includes a first cladding layer, an active layer, a second cladding layer, a resonance mode formation layer, and a high refractive index layer. The first cladding layer, the active layer, the second cladding layer, the resonance mode formation layer, and the high refractive index layer mainly contain nitride semiconductors. The high refractive index layer has a refractive index higher than that of any of the first cladding layer, the active layer, the second cladding layer, and the resonance mode formation layer, and has a superlattice structure in which two or more layers having refractive indices different from each other are repeatedly laminated.