A theoretical framework and the computational infrastructure for optical characterization of a waveguide (WG) photodetector (PD) are presented based on multiples quantum well (MQW) with a rib structure that is able to resolve a light pulse with a temporal width of 10fs. Such pulses are limited to the C-band of optical telecommunications. This pulse width is shorter than the temporal resolution limit of a commercial PD, due to the nonlinear phenomenon known as nondegenerate two-photon absorption (ND2PA). The results show the importance of the operating characteristics that affect carrier generation rate (CGR). © 2019 World Scientific Publishing Company.