Four wave mixing in multimode hollow core waveguides with a two-color pump for the thorium nuclear clockI. Babushkin, Ph. Mosel, K. S. Karda, A. Demircan, A. Trabattoni, M. Kovacev and U. MorgnerEPJ Web Conf., 267 (2022) 02039DOI: https://doi.org/10.1051/epjconf/202226702039