VCSEL Lenticular Medium Downward Convex Refraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional vertical cavity surface emitting laser diodes (VCSELs) face challenges in reproducibility and production stability, with difficulties in achieving small divergence angles, excellent small signal characteristics, and low mode partition noise, particularly due to issues with the production of interlayer dielectric films and upper electrode metallic films with uniform thickness and adhesion strength, and the output of all oscillation modes leading to increased divergence angles and reduced coupling efficiency with optical fibers.
Innovation Solution
A VCSEL design incorporating a lenticular medium with a downward convex surface between the upper semiconductor reflector and the metallic upper electrode, which refracts higher mode light towards the optical axis, reducing divergence angles and improving coupling efficiency, while allowing uniform and reproducible formation of interlayer dielectric films and upper electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a VCSEL has upward convex lens surface structure, then the divergence angle can be reduced, but it is difficult to produce interlayer dielectric film and upper electrode metallic film with uniform thickness and sufficient adhesion strength
Solution Approach 1:
The patent inverts the conventional upward convex lens surface structure to a downward convex structure. This inversion allows the interlayer dielectric film and upper electrode metallic film to be deposited on a more accessible surface geometry, achieving uniform thickness and sufficient adhesion strength while still providing the necessary optical focusing function through the downward convex curvature.
2Reliability
If all oscillation modes are output, then mode partition noise increases, but coupling efficiency with optical fiber decreases due to increased divergence angle
Solution Approach 1:
The downward convex lens surface structure provides localized optical control, refracting higher mode light rays toward the optical axis in a controlled manner. This local quality enhancement at the lens surface allows selective manipulation of different mode components, reducing the overall divergence angle while maintaining stable mode output characteristics.
3Shape
If the aperture diameter ratio between upper electrode and current confinement structure is optimized, then higher mode laser light is blocked, but the structure complexity increases
Solution Approach 1:
The patent employs a downward convex curved surface structure for the lens, which provides smooth optical mode control without requiring complex aperture geometries. The continuous curvature of the lens surface naturally filters higher modes through geometric optics principles, achieving mode control with simpler structural implementation compared to multi-aperture designs.
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 VCSEL achieves improved coupling efficiency with optical fibers, reduced mode partition noise, and enhanced production stability by refracting higher mode light and ensuring uniform film thickness and adhesion strength, resulting in better small and large signal characteristics.
Implementation Method 1
A VCSEL design incorporating a lenticular medium with a downward convex surface between the upper semiconductor reflector and the metallic upper electrode, which refracts higher mode light towards the optical axis, reducing divergence angles
Data Source
AI summary
A vertical cavity surface emitting laser diode includes a lower semiconductor reflector, an active region, an upper semiconductor reflector constituting a resonator with the lower semiconductor reflector, a metallic part being formed on the upper semiconductor reflector, which has a first aperture defining an output region of laser light generated in the active region, and a light confining region being provided between the metallic part and the lower semiconductor reflector, and having a second aperture defining an emission region of the laser light. The upper semiconductor reflector includes a lenticular medium having a convex surface toward the lower semiconductor reflector.