Embodiments herein describe photonic systems that include a germanium photodetector thermally coupled to a resistive element. Current flowing through the resistive element increases the temperature of the resistive element. Heat from the resistive element increases the temperature of the thermally coupled photodetector. Increasing the temperature of the photodetector increases the responsivity of the photodetector. The bias voltage of the photodetector can be increased to increase the bandwidth of the photodetector. In various embodiments, the photodetector includes at least one waveguide to receive light into the photodetector. Other embodiments include multiple resistive elements thermally coupled to the photodetector.