Vertical Light Emitting Device Surface Flatness and Mode Stability
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Solution Overview
Problem
Conventional vertical resonance surface emitting laser devices experience unintended high-order transverse modes due to level differences in the surface on which the upper multilayer reflective mirror is layered, leading to inefficiencies in laser light output.
Innovation Solution
A vertical light emitting device is designed with an upper and lower multilayer reflective film, an intermediate layer of different composition, and an electrode portion that sandwiches the intermediate layer, creating a level difference to restrict the high-order transverse mode without distorting the basic mode field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dielectric layer is formed directly below an upper multilayer reflective mirror, then a level difference occurs in the surface, but this causes each layer in the upper multilayer reflective mirror to have an incline, leading to unintended high-order transverse modes
Solution Approach 1:
An intermediate layer is introduced between the dielectric layer and the upper multilayer reflective mirror. This intermediate layer acts as a mediator that compensates for the level difference caused by the dielectric layer, providing a flat surface for the upper multilayer reflective mirror while maintaining the beneficial effects of the dielectric layer below.
Solution Approach 2:
The structure is divided into multiple functional layers: a dielectric layer for electrical isolation, an intermediate layer for surface flattening, and an upper multilayer reflective mirror for optical reflection. This segmentation allows each layer to perform its specific function without interfering with the others, resolving the contradiction between surface flatness and mode stability.
2Shape
If the central portion of each layer in the upper multilayer reflective mirror protrudes due to inclination, then the position of the inclination expands outward in higher layers, but this expansion causes unintended high-order transverse modes in the output laser light
Solution Approach 1:
The intermediate layer serves as a mediator that prevents the inclination from expanding outward in higher layers. By providing a flat surface for the upper multilayer reflective mirror, it stops the propagation of the inclination effect, thereby preventing the generation of high-order transverse modes while allowing the desired layer geometry to be maintained.
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 solution effectively restricts high-order transverse modes, reducing random jitter and relative intensity noise, while maintaining high operating speed and low threshold current, as demonstrated by experimental results.
Implementation Method 1
an upper multilayer reflective film and a lower multilayer reflective film that are formed facing each other and oscillate light
Data Source
AI summary
Provided is a vertical light emitting device comprising an upper multilayer reflective film and a lower multilayer reflective film that are formed facing each other and oscillate light; an intermediate layer that is formed below the upper multilayer reflective film and includes a layer having a different composition than the upper multilayer reflective film; and an electrode portion that is formed to sandwich the intermediate layer in a cross-sectional plane parallel to an oscillation direction of the light and to have a top end that is higher than a top surface of the intermediate layer. After the electrode portion is formed to sandwich the intermediate layer, the upper multilayer reflective film is layered on the intermediate layer.