Mode analysis of atmospheric turbulence mitigation with Multi-Plane Light Conversion

Abstract

Developing standard and accessible atmospheric turbulence mitigation is of paramount importance to enable laser communication network deployment. Multi-Plane Light Conversion (MPLC) [1]–[3] is proving to be an effective technique to improve coupling efficiency of a perturbated wave-front profile towards a single-mode fiber [4]–[6]. However, to date, experimental studies are restricted to a fixed number of modes. In this work, we numerically and experimentally study performance improvement of the MPLC technique and mode collection compared to direct single mode fiber coupling for several D/r0 ratio, D being the receiver aperture diameter and r0 the Fried parameter. We calculate the coupling efficiency, represented in Fig 1. Collection for SMF only is shown in Fig 1-a while the summation of the 15 first Hermite-Gaussian modes is represented in Fig 1-b. Collection for each mode for D/r0=4 is displayed in Fig 1-c. We demonstrate that 15 modes MPLC appears to be a good compromise between number of modes and complexity of the device. This configuration typically improves the collection efficiency by >7 dB in the case of strong turbulence when D/r0 >4. More important, the minimum collection efficiency that would correspond to a link failure is dramatically increased compared to SMF fiber alone. MPLC thus shows high robustness to turbulence fluctuation.