**2. Optimisation of nanophotonics design by deep learning**

Recently, deep learning using an artificial neural network has emerged as a revolutionary and powerful methodology in nanophotonics field. Applying the deep learning algorithms to the nanophotonic inverse design can introduce remarkable design flexibility which is very challenging and even impossible to achieve based on conventional optimisation approaches [1]. In this section, we will provide a brief review of the implementation of deep learning to solve nanophotonic inverse design problems.
