Evaluation of a photonic lantern spatial demultiplexer based receiver for optical communication

In this paper, we present a method based on a modal decomposition to quantify the efficiency of photonic lanterns (PLs) based free space optical (FSO) communication receivers. We fabricate a seven-port PL, and we evaluate numerically the free space to fiber coupling efficiency based on a reconstruction of the fields at the PL FSO multimode port. We validate the numerical approach with an experimental characterization of the PL. Then we compare the PL to a commercial multiplane light converter spatial demultiplexer. The PL shows better coupling efficiency for low-order spatial modes with orders of magnitude of demultiplexer size reduction. Finally, we evaluate the PL receiver with a simulation of received optical wavefront in a FSO communication.