Surface-Emitting Laser Reflector Stack With Film Thickness Modulation
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Solution Overview
Problem
In light emitting elements with surface emitting laser elements, maintaining the interface state between the first light reflecting layer and the laminated structure is challenging, leading to optical loss, increased threshold, reduced light emission efficiency, and lower light quality.
Innovation Solution
Incorporating a film thickness modulating layer between the laminated structure and the first light reflecting layer, where the first light reflecting layer is structured with alternately laminated thin films of different optical thicknesses, and the film thickness modulating layer is designed to minimize optical loss by controlling the refractive indices and thickness ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the first light reflecting layer or the laminated structure is formed using conventional methods, then the light emitting element can be manufactured, but the interface state between the first light reflecting layer and the laminated structure deteriorates, causing optical loss
Solution Approach 1:
The patent introduces a film thickness modulating layer as an intermediary between the first light reflecting layer and the laminated structure. This intermediate layer modulates the film thickness to control the optical field distribution, preventing strong optical fields from forming at the problematic interface and thereby reducing optical loss without compromising manufacturing feasibility
Solution Approach 2:
The patent changes the physical parameter of film thickness in the modulating layer to alter the optical field distribution. By carefully controlling the thickness of the modulating layer, the optical field is redistributed away from the interface region, reducing light absorption and scattering losses while maintaining acceptable manufacturing precision
2Ease of manufacture
If the interface state is not favorably maintained, then manufacturing is simpler, but optical loss increases due to light absorption and scattering
Solution Approach 1:
The film thickness modulating layer serves as a mediator that allows the interface to be formed using conventional simpler methods while still achieving low optical loss. The modulating layer compensates for interface imperfections by controlling the optical field distribution, decoupling the ease of manufacture from the optical performance
3Loss of energy
If optical loss is reduced by improving interface state, then light emission efficiency increases, but device complexity increases due to additional layer structure
Solution Approach 1:
The patent segments the device structure by adding a dedicated film thickness modulating layer that performs the specific function of optical field control. This segmentation allows the optical loss reduction function to be isolated in a specific layer, making the complexity localized and manageable while achieving the desired performance improvement
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 effectively reduces optical loss at the interface, preventing increases in threshold and maintaining high light emission efficiency and quality by ensuring strong optical field regions do not form at critical interfaces.
Implementation Method 1
laser oscillation generally occurs when laser light is caused to produce resonance between two light reflecting layers (Distributed Bragg Reflector layers, i.e., DBR layers)
Implementation Method 2
a first light reflecting layer including a plurality of thin films laminated to each other is formed on the exposed surface of a substrate
Data Source
AI summary
A light emitting element according to the present disclosure includes a first light reflecting layer 41, a laminated structure 20, and a second light reflecting layer 42 laminated to each other. The laminated structure 20 includes a first compound semiconductor layer 21, a light emitting layer 23, and a second compound semiconductor layer 22 laminated to each other from a side of the first light reflecting layer. Light from the laminated structure 20 is emitted to an outside via the first light reflecting layer 41 or the second light reflecting layer 42. The first light reflecting layer 41 has a structure in which at least two types of thin films 41A and 41B are alternately laminated to each other in plural numbers. A film thickness modulating layer 80 is provided between the laminated structure 20 and the first light reflecting layer 41.