An overview of Mg-based IR nonlinear optical materials

Abstract

Infrared nonlinear optical (IR-NLO) materials play a vital role in generating IR laser output and have significant applications in the fields of communication, medicine, and security. At present, commercial IR-NLO crystals suffer from various performance drawbacks that constrain their range of applications. Therefore, the pursuit of designing and exploring new IR-NLO materials has emerged as an important avenue for the advancement of the IR laser industry. Benefiting from the various structural compositions, wide energy gaps, sufficient second-harmonic-generation intensities, strong laser-induced damage thresholds and favorable phase matching features, Mg-based IR-NLO materials have attracted wide attention in recent years. However, there has not been a specific review of this attractive family. In this overview, the recent advancements of Mg-based IR-NLO materials are summarized. These non-centrosymmetric compounds (including 36 chalcogenides and 4 pnictides) can be categorized into three types based on their chemical compositions: (i) ternary MgGa2Se4, MgSiP2, MgSiAs2, and Mg3Si6As8; (ii) quaternary Li4MgGe2S7, Li2Mg2MIII2S6 (MIII = Si, Ge), AEMg6Ga6S16 (AE = Ca, Sr, Ba), RE6MgSi2S14 (RE = Y, La-Nd, Sm, and Gd-Er), Li2MgMIVSe4 (MIV = Ge, Sn), Na4MgMIII2Se6 (MIII = Si, Ge), Cu2MgMIVQ4 (MIV = Si, Ge; Q = S, Se), MIMg3MIII3Q8 (MI = Na, Cu, Ag; MIII = Al, Ga; Q = S, Se), and Mg2In3Si2P7; and (iii) quinary Ba6Cu1.9Mg1.1Ge4S16 and Ba6Cu1.94Mg1.06Sn4S16. Their solid-state synthesis, crystal structures, optical properties and structure-activity relationships are systematically discussed. Finally, some useful conclusions and outlooks on this topic have been put forward.