The non-linear third order susceptibility of Cu2 (M = Zn, Ni, Co)SnS4 coated on perovskite thin films

The third-order nonlinearity of Cu2(M = Zn, Ni, Co)SnS4 (CMTS) and perovskite/CMTS films were investigated by a single-beam Z-scan technique. The non-linear absorption (NLA) analysis in an open aperture Z-scan setup reveals a saturable absorption phenomenon. The self-focusing of the transmission curve of the close aperture indicates a positive sign for the non-linear refraction (NLR) index in all samples. Interestingly, NLR index, NLA coefficient, and absolute third-order susceptibility of perovskite/CMTS films are improved compared to the pristine CMTS layer and pristine perovskite, and the record NLR index is attributed to perovskite/Cu2ZnSnS4 one. The results open a broad range in photonic and optical limiting applications.