EXPERIMENTAL ANALYSIS OF THE EFFECTS OF SINGLE-PHASE IMMERSION COOLING OF OPTICAL INTERCONNECTS ON MECHANICAL PROPERTIES OF ACTIVE OPTICAL CABLES

Abstract

Active optical cables (AOC) are being increasingly adopted for data communication and storage, networking, and high-performance computing (HPC) applications. However, their ability to meet higher data-rate requirements necessitates increased heat dissipation demands in fiberoptic datacom systems. Many dielectric coolants having heat capacities much higher than that of air are available in the market. However, there is a lack of literature and data on the reliability of using single-phase dielectric fluids for immersion-cooling of inter and intra-rack optical interconnections in data centers. Industry standards and prevalent aging test methods for optical cables prove insufficient as they do not address immersion in these coolants. In this work, the mechanical behavior of an active optical cable (AOC) aged in a single-phase dielectric coolant has been studied. Accelerated aging conditions were achieved by immersing the cable in zero-stress condition in jars containing mineral oil and commercial synthetic engineered fluid placed in a climatic chamber at an elevated temperature for a total duration of 288 hours. Samples were removed every 72 hours for subsequent mechanical testing and microscopy. Scanning Electron Microscopy was used to assess surface morphology, and the thermomechanical properties were characterized using a Dynamic Mechanical Analyzer (DMA). Necessary comparisons were made with the as-received cable samples. The potential for application of Arrhenius extrapolation method to model temperature-dependent properties of the samples was explored, and mathematical modeling of evolution of the Young’s modulus with time was done to understand the degradation attributable to possible chemical interactions between the cable jacket and the engineered fluid.