We propose a method for finding 2D spatial modes of thermal field through a direct measurement of the field intensity and an offline analysis of its spatial fluctuations. Using this method, in a simple and efficient way we reconstruct the modes of a multimode fiber and the spatial Schmidt modes of squeezed vacuum generated via high-gain parametric down conversion. The reconstructed shapes agree with the theoretical results.
@article{arxiv.2009.01778,
title = {Reconstructing 2D spatial modes for classical and quantum light},
author = {Valentin A. Averchenko and Gaetano Frascella and Mahmoud Kalash and Andrea Cavanna and Maria V. Chekhova},
journal= {arXiv preprint arXiv:2009.01778},
year = {2020}
}