Push-Pull Modulated VCSELs for High-Speed Data Links
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Solution Overview
Problem
Current vertical cavity surface emitting lasers (VCSELs) face challenges in achieving high modulation bandwidths greater than 10 Gbps due to reduced device reliability at high current densities, which limits their practical application in high-speed data communications.
Innovation Solution
A multiple resonant cavity vertical cavity surface emitting laser (VCSEL) design with two outer distributed Bragg reflector mirrors and two multi-quantum well active regions separated by an intermediate mirror, allowing independent biasing and modulation of each cavity to increase photon density and achieve high modulation rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high current density is used to achieve high modulation bandwidth, then modulation bandwidth increases, but device reliability deteriorates
Solution Approach 1:
The laser device is divided into multiple independent resonant cavities (first cavity and second cavity), each with its own active region and capable of independent operation. This segmentation allows the total modulation bandwidth requirement to be distributed across multiple cavities, reducing the current density burden on each individual cavity while maintaining high overall modulation bandwidth through coupled operation.
2Speed
If single cavity design is used, then device complexity is low, but modulation bandwidth is limited
Solution Approach 1:
The patent implements a nested cavity structure where the first and second resonant cavities are coupled through shared distributed Bragg reflector mirrors. The cavities are nested within a common structural framework, allowing them to share optical components (mirrors) while maintaining independent active regions. This nesting approach increases modulation bandwidth compared to a single cavity while avoiding the full complexity of completely independent laser structures.
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 design enables modulation bandwidths exceeding 80 GHz with reduced relaxation oscillation effects, improving both the intrinsic laser bandwidth and reliability, making it suitable for future high-speed data communication requirements.
Implementation Method 1
two outer distributed Bragg reflector mirrors
Implementation Method 2
two multi-quantum well active regions separated by an intermediate mirror, allowing independent biasing and modulation of each cavity to increase photon density
Data Source
AI summary
A laser system having separately electrically operable cavities for emitting modulated narrow linewidth light with first, second and third mirror structures separated by a first active region between the first and the second and by a second active region between the second and the third. The second mirror structure has twenty of more periods of mirror pairs.