Surface Emitting Laser Diode with Tilted Mirror Recess
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional surface emitting laser structures suffer from poor light extraction efficiency, large divergence angles, and increased response time due to non-conductive passivation layers and inadequate resonant cavity design, leading to signal attenuation and failure to meet user requirements for high-speed operation and vertical light emission.
Innovation Solution
A surface emitting laser diode structure featuring a thermal conductivity insulating substrate, a recessed bonding layer with a trapezoidal cylinder, an electrically conductive protective layer, a reflecting mirror with tilted sides, a current isolating layer, and a band-pass layer that forms a resonant cavity with reduced divergence and enhanced reflectance, allowing for efficient light emission and increased response speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-conductive passivation layer is used to prevent short circuit, then electrical insulation is improved, but light extraction efficiency deteriorates because electroluminescence leaks from the passivation layer
Solution Approach 1:
The device is segmented into distinct functional regions: the bonding layer with recess is dedicated to light extraction, while the passivation layer is dedicated to electrical insulation. This segmentation allows each component to optimize its specific function without compromising the other.
Solution Approach 2:
The bonding layer is positioned locally at the light-emitting region where light extraction is critical, while the passivation layer covers other areas where electrical insulation is paramount. This local quality differentiation resolves the contradiction by assigning different material properties to different spatial locations.
2Illumination intensity
If the luminescent diode area is increased to improve light extraction efficiency, then light output is improved, but response time increases
Solution Approach 1:
The bonding layer extracts light laterally from the luminescent diode region, allowing the luminescent diode to maintain a small area for fast response while still achieving high light extraction efficiency through the dedicated bonding layer structure.
Solution Approach 2:
Light extraction is moved from the vertical dimension (through the passivation layer) to the lateral dimension (through the bonding layer with recess), enabling efficient light extraction without increasing the luminescent diode area.
3Ease of operation
If the impressed current distribution layer area is increased to control current flow direction, then current control is improved, but the effective area of the lower reflecting layer decreases
Solution Approach 1:
The bonding layer is designed with an asymmetric structure featuring a recess, allowing it to perform both current distribution and light extraction functions efficiently without requiring a large symmetric area that would encroach on the reflecting layer.
Solution Approach 2:
The bonding layer serves multiple functions: it acts as a current distribution layer to control current flow direction and simultaneously functions as a light extraction layer through its recess structure, eliminating the need for separate large-area current control structures.
4Ease of manufacture
If traditional surface emitting laser structure is used, then manufacturing simplicity is maintained, but light divergence angle is large and signal attenuation occurs
Solution Approach 1:
The bonding layer incorporates a recess with curved surfaces that focus and collimate the emitted light, reducing the divergence angle while maintaining a relatively simple manufacturing process compatible with existing semiconductor fabrication techniques.
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 structure achieves a small divergence angle, reduces lateral light leakage, and enhances response speed by forming a leak-proof resonant cavity and optimizing current flow direction, thereby improving light extraction efficiency and meeting user demands for high-speed operation.
Implementation Method 1
most of the electroluminescence is reflected repeatedly between the lower reflecting layer 6 and the upper reflecting layer 9 and keeps emitting on the luminescent diode 8. Then, the electroluminescence resonates with the luminescent diode 8 to generate new electroluminescence.
Implementation Method 2
The band-pass layer 10 is capable of reflecting incident light with a wavelength in a particular range, allows the incident light with the wavelength in the particular range to pass therethrough
Implementation Method 3
the electroluminescence generated by the luminescent diode 8
Data Source
AI summary
The present invention is a surface emitting laser luminescent diode structure which is characterized in that a recess comprises two tilted slopes on two sides and a protruding trapezoidal cylinder located at the bottom center of the recess is disposed at the bottom of a laser resonant cavity. Thus, a reflecting mirror disposed along the surface of the recess includes two tilted side surfaces as leak-proof sides, which reduces the divergence angle and avoid the lateral light leakage. Additionally, a current isolating layer is disposed on the reflecting mirror and is designed to satisfy the condition (¼*wavelength*1/refractive index) of an optical film, thereby allowing the reflecting mirror to receive an excellent reflectance. Besides, the current isolating layer limits the flow direction of the current, thus increasing operating speed.