VCSEL Grating Layer Transparent Electrode Design
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Solution Overview
Problem
Conventional semiconductor laser diodes with optical cavities parallel to the surface are not suitable for low-cost mass manufacturing and fabrication of two-dimensional arrays, limiting their application in displays, light sources, and optical fiber data links.
Innovation Solution
The development of vertical cavity surface emitting laser diodes (VCSELs) with a grating layer and transparent electrodes replaces the traditional DBR mirror structure and non-transparent electrodes, allowing for a more compact design that requires less current and facilitates the construction of arrays in a smaller space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional semiconductor laser diodes with optical cavities parallel to the surface are used, then light emission is achieved, but mass manufacturing and fabrication of two-dimensional arrays become costly and complex
Solution Approach 1:
The patent inverts the conventional laser diode structure by changing the optical cavity orientation from parallel to perpendicular relative to the semiconductor wafer surface. This inversion enables vertical cavity surface emitting laser diodes (VCSELs) that can be fabricated using standard planar semiconductor manufacturing processes, allowing for low-cost mass production and two-dimensional arrays.
2Volume of moving object
If VCSELs with grating layer and transparent electrodes are used, then device size is reduced and current requirement is lowered, but structural complexity increases
Solution Approach 1:
The patent introduces a grating layer with specific refractive index parameters and periodic structures to achieve wavelength-selective feedback and directional emission. By carefully controlling the grating period, depth, and refractive index contrast, the device achieves compact size and low current operation while the grating structure provides the necessary optical functionality.
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 approach results in a more compact, energy-efficient laser diode capable of emitting light in a specific direction, suitable for various optical and electrical applications, with adjustable emission direction depending on the grating layer design.
Implementation Method 1
A grating layer having a predetermined index of refraction is disposed adjacent a top surface of the current concentrating layer. The grating layer processes photons emitted from the multiple quantum well structure
Implementation Method 2
A grating layer having a predetermined index of refraction is disposed adjacent a top surface of the current concentrating layer
Implementation Method 3
Electrical power is applied between electrodes creating a current flow across the active layer resulting in an electron population inversion which generates energy in the form of photons
Implementation Method 4
surrounding reflective surfaces constructed from alternating layers of materials which direct light to an extraction point on the diode
Implementation Method 5
The reflective regions are constructed from alternating layers of mirrors with different indices of refraction. The stacks form a structure known as a distributed Bragg reflector mirror structure
Data Source
AI summary
A laser diode is provided comprising a multiple quantum well structure, a current concentrating layer having an oxide-confined aperture, a grating layer having an index of refraction, and a transparent electrode, wherein the transparent electrode has an index of refraction less than the index of refraction of the grating layer.