A Simple Numerical Model to Estimate the Temperature Distributions Over Photodetectors in Steady-State

This research introduces an approximation method for computing the temperature distribution in photodetectors operating in a steady state under optical excitation. The derived temperature profile is utilized to assess the impact of temperature variations on crucial performance metrics of photodetectors, encompassing quantum efficiency, bandwidth, and phase noise. Our methodology, grounded in simplified heat transport equations, yields significant insights into the intricate relationship between temperature and photodetector performance. Our findings reveal that assuming constant room temperature operation leads to an overestimate of the output current and quantum efficiency and an underestimate of bandwidth, by contrast, a model in which the temperature varies produces estimates that closely align with experimentally-measured values for quantum efficiency and bandwidth. The low thermal conductivity of InGaAs hampers heat dissipation, resulting in temperature accumulation. Varying the reverse bias voltage while keeping the output current constant by changing the input optical power leads to nonlinear variations in the bandwidth, phase noise, and quantum efficiency. These insights contribute to the understanding and optimization of thermal management in photodetectors under strong optical excitations.