Thermal considerations of multi-emitter quantum cascade laser platform for application in mid-infrared photonic integrated circuits

In this paper, research concerning the thermal management for multi-emitter Quantum Cascade Lasers (QCLs) is presented. Multiple QCL chips are integrated on one platform. Our study encompasses a comprehensive examination of thermal crosstalk effects and packaging-related issues through a combination of numerical simulations and experimental investigations. The subject of our investigation comprises mid-infrared QCLs, which were mounted on an aluminum nitride submount. Our results indicate a substantial elevation in the temperature gradient observed within the middle emitter, situated on the aforementioned substrate, irrespective of whether a single laser or a trio of lasers is operating. This outcome suggests that the presence of three lasers exerts an influence on the elevated temperature experienced by the central QCL, while the thermal conductivity of the submount (platform) plays a pivotal role in determining the magnitude of the temperature offset and the overall temperature increase across the entire laser chip. These conclusions are very important in improving the thermal performance of multi-emitter QCLs integrated on any kind of platform in case of integration.