Thermal design and experimental validation for optical transmitters

摘要

This paper describes a thermal design methodology for a 2.5 Gbps optical transmitter that mainly comprises a laser array of 12 VCSELs and a laser driver module. An integrated heat sink design was performed and optimized through modeling and simulation. Temperature regulation of the laser array has been performed through design and optimization of the thermal path (cavity and heat spreader) and separations (wire bonding lengths). Detailed module simulation was performed after the heat sink design and the temperature regulations. To validate the simulation results, a test vehicle of 2.5 Gbps transmitter was built up and tested under various thermal conditions. The airflow rate and ambient temperature were controlled by a wind tunnel. It has shown that the experimental and detailed module simulation results are comparable. A cooling solution with natural convection has been achieved so that the case temperature can be kept under 70 ℃ without using a fan. The modeling and simulation were done by using a computational fluid dynamics (CFD) program.