Mode Visualization and Control of Complex Lasers Using Neural Networks.

Visualizing the behavior of complex laser systems is an outstanding challenge, especially in the presence of nonlinear mode interactions. Hidden features, such as the gain distributions and spatial localization of lasing modes, often cannot be revealed experimentally, yet they are crucial to determining the laser action. Here, we introduce an experimental lasing spectroscopy method that visualizes the gain profiles of the modes in a complex, disorderly coupled microring array laser using an artificial neural network. The spatial gain distributions of the lasing modes are reconstructed without prior knowledge of the laser device. We further extend the neural network to a tandem neural network that can control the laser emission by matching the modal gain/loss profile to selectively enhance the targeted modes. This mode visualization method offers a new approach to extracting hidden spatial mode features from photonic structures, which could improve our understanding and control of complex photonic systems.