Ti3C2Tx MXene Enabled All-Optical Nonlinear Activation Function for On-Chip Photonic Deep Neural Networks

Abstract

Neural networks are one of the first major milestones in developing artificial intelligence systems. The utilisation of integrated photonics in neural networks offers a promising alternative approach to microelectronic and hybrid optical-electronic implementations due to improvements in computational speed and low energy consumption in machine-learning tasks. However, at present, most of the neural network hardware systems are still electronic-based due to a lack of optical realisation of the nonlinear activation function. Here, we experimentally demonstrate two novel approaches for implementing an all-optical neural nonlinear activation function based on utilising unique light-matter interactions in 2D Ti3C2Tx (MXene) in the infrared (IR) range in two configurations: 1) a saturable absorber made of MXene thin film, and 2) a silicon waveguide with MXene flakes overlayer. These configurations may serve as nonlinear units in photonic neural networks, while their nonlinear transfer function can be flexibly designed to optimise the performance of different neuromorphic tasks, depending on the operating wavelength. The proposed configurations are reconfigurable and can therefore be adjusted for various applications without the need to modify the physical structure. We confirm the capability and feasibility of the obtained results in machine-learning applications via an Modified National Institute of Standards and Technology (MNIST) handwritten digit classifications task, with near 99% accuracy. Our developed concept for an all-optical neuron is expected to constitute a major step towards the realization of all-optically implemented deep neural networks.

MXene‐Based Broadband Ultrafast Nonlinear Activator for Optical Computing

“…In addition, it was known from the spectral information in the TAS that the MXene nonlinear response also had a significant wavelength dependence, which is consistent with the previous study. [ 19 ] Therefore, based on the wavelength and intensity dependences of MXene optical transmission, our nonlinear activator showed promising configuration reconfigurability properties, implying that it can be used for different types of ONNs.…”

“…Recently, researchers have deposited Ti 3 C 2 T x nanosheets directly onto a rib waveguide to provide nonlinear activation using the nonlinearity of the Ti 3 C 2 T x . [ 19 ] This has the advantage of fast response and ease of integration, but that work did not examine in detail what factors affect the performance of the nonlinear activator. There is an urgent need to conduct in‐depth research on the factors affecting the performance of nonlinear activators and to establish a criterion for them, which will benefit the development of nonlinear activators and accelerate the integration of ONNs with AI.…”