All-optical nonlinear activation function based on Germanium Silicon composite waveguide

Nonlinear activation functions, a part of artificial neuron network, is responsible for nonlinearly mapping the input of the neuron to the output. The optical realization of nonlinear activation functions has become a research hotspot, which is optical activation function. Here, we propose and experimentally demonstrate an all-optical implementation of optical activation function based on germanium silicon composite waveguide, which takes advantage of the intrinsic absorption and the plasma dispersion effect of germanium in the communication band. It realizes two different nonlinear activation functions. This proves that our scheme has a great potential for optical activation functions.