Active-Passive VCSEL Coupling for Higher-Order Mode Suppression
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Solution Overview
Problem
Current VCSEL devices suffer from low modal discrimination, leading to multi-mode lasing and associated instabilities such as strong mode competition and reduced laser modulation bandwidth.
Innovation Solution
The implementation of an emitter device with both active and passive emitters, where the passive emitters are positioned to couple with higher-order modes of the active emitter, thereby filtering out these modes and enhancing modal discrimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a VCSEL device operates without mode discrimination, then multi-mode lasing occurs, but this leads to strong mode competition and reduced laser modulation bandwidth
Solution Approach 1:
A passive VCSEL is introduced as an intermediary device that couples with higher-order modes of the active VCSEL through evanescent field interaction. The passive VCSEL acts as a mediator that selectively interacts with unwanted higher-order modes without being electrically pumped, thereby suppressing these modes and reducing mode competition in the active VCSEL.
Solution Approach 2:
The harmful higher-order modes are extracted from the active VCSEL by coupling them to the passive VCSEL. The passive VCSEL selectively interacts with and removes these unwanted modes through evanescent field coupling, allowing the active VCSEL to operate with improved modal discrimination and reduced mode competition.
2Manufacturing precision
If passive VCSELs are positioned to couple with higher-order modes, then modal discrimination is enhanced, but device complexity increases
Solution Approach 1:
The emitter device is segmented into functionally distinct components: an active VCSEL that provides optical gain and is electrically pumped, and one or more passive VCSELs that are not electrically pumped but couple with higher-order modes. This segmentation allows each component to perform its specific function, achieving improved modal discrimination while maintaining a relatively simple overall structure that can be fabricated using standard VCSEL fabrication processes.
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 effectively suppresses undesired higher-order modes, allowing for lasing with lower-order modes and improving beam quality, intensity noise, phase noise, and side mode suppression ratio.
Implementation Method 1
The at least one passive VCSEL may be positioned relative to the active VCSEL to cause coupling of one or more modes of the active VCSEL with one or more modes of the at least one passive VCSEL
Data Source
AI summary
In some implementations, a vertical cavity surface emitting laser (VCSEL) device includes a substrate layer and a set of epitaxial layers disposed on the substrate layer. The VCSEL device may include an active VCSEL formed in the set of epitaxial layers, where the active VCSEL is configured such that electrical pumping that provides optical gain for lasing is to be present in the active VCSEL. The VCSEL device may include at least one passive VCSEL formed in the set of epitaxial layers, where the passive VCSEL is configured such that electrical pumping that provides optical gain for lasing is to be absent in the at least one passive VCSEL. The at least one passive VCSEL may be positioned relative to the active VCSEL to cause coupling of one or more modes of the active VCSEL with one or more modes of the at least one passive VCSEL.