All optical on-chip nonlinear activation functions for multi-wavelength computation

This work proposes an all-optical on-chip nonlinear activation function unit for multi-wavelength computing applications. Our proposed unit utilizes the unique properties of silicon, specifically the two-photon absorption and thermo-optic effects, to achieve nonlinearity essential for optical neural networks. We designed the parameters of the corresponding unit structure through simulation, fabricated and tested the actual structure experimentally, and obtained a CELU-like response curve. In practical classification tasks, we evaluated its performance in various classification tasks through numerical simulation and achieved a recognition accuracy of 98.84% on the MNIST dataset. This work addresses a critical gap in multi-wavelength systems and contributes to the development of more powerful and efficient optical computing platforms.