Spatial diversity control law for demultiplexer and active photonic integrated circuits for atmospheric effect mitigation

• Main Authors: Lucas, Yann, Michau, Vincent, Meimon, Serge
• Format: Conference Proceeding
• Language: English
• Published: SPIE 12.03.2024
• ISBN: 9781510670143; 1510670149
• ISSN: 0277-786X
• DOI: 10.1117/12.3001602

Free-space optical links theoretically allow very high-speed data rates. As the beams propagate through the atmosphere, the effects of turbulence introduce fading. To mitigate these effects, adaptive optics is commonly implemented. Recently, a spatial demultiplexer coupled to an active integrated photonic circuit has been proposed as a more compact solution to replace the adaptive optics device. This solution has been the subject of several demonstrations. In these demonstrations, the control of the photonic circuit is carried out by modulation or by criterion minimization. These techniques are demanding in terms of modulation bandwidth, particularly when the number of spatial modes to be corrected increases. We propose a control method allowing the increase of the number of corrected modes without increasing the modulation bandwidth. This control method is based on a spatial coding of the modulation, also called spatial diversity. Unlike state-of-the-art techniques in which modes are controlled sequentially, with spatial diversity, all the modes are controlled at the same time. Spatial diversity closed loop stability is demonstrated in a numerical simulation.