Thermal challenges for packaging integrated photonic devices

In this work, we present thermal imaging and analysis of a silicon photonic optical network unit (ONU) for next generation passive optical networks (NG-PONs). A high-speed thermal camera is used to capture both the dynamic and steady-state temperatures of the photonic integrated circuit (PIC) and electric integrated circuit (EIC) at the core of the ONU. The dynamic temperature measurements of the PIC and EIC on powering-up the ONU show several distinct “steps” before the steady-state temperature is reached, and we show that these features can be predicted and fitted using a simple lumped-element rate-equation model. Steady-state temperature measurements made by mounting the ONU module on a thermally-stabilized stage allow the coefficient of performance (COP) of the thermoelectric cooler (TEC) in the module to be evaluated for simulated ambient temperatures ranging from 15-45 °C. This provides valuable information on the operational cost of the ONU in the field, where temperature-stabilization of the PIC represents a significant fraction of the overall power-budget.