Inorganic polycations induce widening of infrared transparency spectrum

As core components for generating coherent tunable radiation sources in all-solid-state lasers, second-order nonlinear optical (NLO) crystals have demonstrated significant technical advantages in many fields. Metal chalcogenides with tetrahedral cluster (Tn) as the structural unit are regarded as candidate systems for NLO materials of the mid- and far-infrared bands due to their potential strong second-harmonic-generation (SHG) response and wide infrared transmission range.