Hybrid Membrane External-Cavity Laser With DBR-Free Thermal Path
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Solution Overview
Problem
The output power of conventional vertical-external-cavity surface-emitting lasers (VECSELs) is limited by thermal management issues due to the high thermal resistance and heat generation in the distributed Bragg reflector (DBR), which restricts power scalability.
Innovation Solution
A hybrid membrane external-cavity surface-emitting laser (H-MECSEL) design that incorporates a semiconductor active gain structure with mirrored heat spreaders and a reflecting structure, allowing for vertical heat transfer and efficient multipass pumping, eliminating the need for a DBR and improving thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a distributed Bragg reflector (DBR) is used in the VECSEL active mirror, then the laser can achieve lasing threshold and sustained oscillation, but the thermal resistance increases significantly due to the thickness and material interfaces, limiting output power
Solution Approach 1:
The patent removes the DBR from the active mirror structure, extracting the problematic thermal barrier while preserving the essential lasing function through an alternative configuration where the DBR is placed separately in the external cavity. This allows the active region to be in direct thermal contact with the heat spreader without the intervening DBR layers.
Solution Approach 2:
The patent introduces a separate external cavity with a second reflector that acts as an intermediary to provide the necessary optical feedback for lasing, replacing the need for the DBR to be integrated in the active mirror. This mediator approach separates the thermal management function from the optical feedback function.
2Reliability
If the DBR thickness is increased to achieve higher reflectivity values, then the required reflectivity is met, but the thermal resistance increases and the active region overheats
Solution Approach 1:
The patent extracts the DBR from the active mirror structure, allowing high reflectivity to be achieved by the separate external cavity reflector while the active mirror focuses on thermal management through direct contact with the heat spreader.
Solution Approach 2:
The patent moves the DBR function to a different spatial location (external cavity) rather than integrating it in the active mirror plane, separating the optical feedback function from the thermal conduction path.
3Power
If pump laser power is increased to achieve higher output power, then the output power increases, but thermal management becomes insufficient and the system reaches its power limit
Solution Approach 1:
The patent extracts the thermal management bottleneck (DBR) from the system, allowing the heat spreader to directly cool the active region without thermal interference, thereby enabling higher pump powers to be converted into output power rather than heat.
Solution Approach 2:
The patent changes the thermal conduction parameter by removing the high-resistance DBR layer, fundamentally altering the heat flow path to enable higher power operation through improved thermal dissipation capability.
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 H-MECSEL design achieves higher power output and improved thermal management, enabling more efficient thermal dissipation and scalability compared to conventional VECSELs.
Implementation Method 1
a first heat spreading structure comprising a top first heat spreading structure surface and a bottom first heat spreading structure surface, wherein the top first heat spreading structure surface is in thermal contact with the bottom active gain surface
Implementation Method 2
a reflecting structure comprising a top reflecting structure surface and a bottom reflecting structure surface, wherein the top reflecting structure surface is in contact with the bottom first heat spreading structure
Data Source
AI summary
A hybrid membrane external-cavity surface-emitting laser is disclosed. The hybrid membrane external-cavity surface-emitting laser includes a semiconductor active gain structure comprising a top active gain surface and a bottom active gain surface; a first heat spreading structure comprising a top first heat spreading structure surface and a bottom first heat spreading structure surface, wherein the top first heat spreading structure surface is in thermal contact with the bottom active gain surface; and a reflecting structure comprising a top reflecting structure surface and a bottom reflecting structure surface, wherein the top reflecting structure surface is in contact with the bottom first heat spreading structure.