Wavelength Variable Light Source Thermal Management
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Solution Overview
Problem
Vertical external cavity surface emitting lasers (VECSELs) face instability in laser oscillation due to heat generated by the excitation light source, leading to insufficient heat dissipation and thermal influence on the integrated unit, which affects the operation of the second mirror and resonator length control.
Innovation Solution
A wavelength variable light source configuration with both the excitation light source and gain medium positioned on a heat sink, utilizing a micro-electro-mechanical system (MEMS) mechanism to control the resonator length and a reflector with wavelength selectivity, ensuring direct cooling and minimizing thermal impact on the MEMS mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the excitation light source and gain medium are stacked in the housing, then the device structure is compact, but thermal influence on the MEMS mechanism increases and stable operation deteriorates
Solution Approach 1:
The heat sink is divided into a first heat sink portion for the excitation light source and a second heat sink portion for the gain medium, physically separating the thermal management zones to prevent heat transfer between components while maintaining compact housing integration
Solution Approach 2:
A temperature stabilization unit is introduced as an intermediary between the second heat sink portion and the gain medium to actively control and stabilize the temperature of the gain medium, preventing thermal drift that would affect MEMS mechanism performance
2Temperature
If the gain medium is disposed on the heat sink, then direct cooling is achieved, but heat from the excitation light source still affects the gain medium through the shared heat sink
Solution Approach 1:
The heat sink is segmented into distinct first and second portions, each dedicated to a specific component, eliminating thermal coupling between the excitation light source and gain medium while maintaining direct cooling for both components
Solution Approach 2:
The temperature stabilization unit acts as a thermal intermediary, decoupling the gain medium from ambient temperature fluctuations and heat transfer from the excitation light source portion of the heat sink
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 configuration suppresses thermal influence, enabling stable operation and wavelength control, allowing for independent temperature stabilization of the gain medium and reducing the need for additional mirrors or lenses, thus achieving stable laser oscillation and wavelength sweeping.
Implementation Method 1
both the excitation light source and the gain medium are disposed on the heat sink. Consequently, not only the excitation light source but also the gain medium are directly cooled by the heat sink
Implementation Method 2
The reflector is configured to reflect the excitation light output from the excitation light source toward the gain medium in the housing
Implementation Method 3
The window is formed in the housing and configured to transmit light output from the gain medium
Implementation Method 4
The light is amplified by the resonator configured from the upper DBR and the lower DBR
Data Source
AI summary
A wavelength variable light source includes a housing, a heat sink disposed in the housing, an excitation light source disposed on the heat sink and configured to output excitation light, a gain medium disposed on the heat sink and including an active layer and a lower DBR, a MEMS mechanism including a movable film facing the gain medium via a gap, disposed on the gain medium, and configured to control the gap, an upper DBR provided in the movable film and configuring a resonator together with the lower DBR, a reflector configured to reflect the excitation light output from the excitation light source toward the gain medium in the housing, and a window formed in the housing and configured to transmit light output from the gain medium.