Recent advances in IR nonlinear optical chalcogenides with well-balanced comprehensive performance

Infrared nonlinear optical (IR-NLO) crystals have attracted many attentions due to the frequency-conversion capability to generate coherent tunable IR laser output for military and civil applications. Chalcogenides as a most popular branch of IR-NLO materials are the competitive candidates owing to their large second-harmonic generation (SHG) coefficient (deff) and broad transmission regions. Currently, how to obtain the non-centrosymmetric (NCS) structure and realize the coexistence of wide energy gap (Eg & GE; 3.0 eV), sufficient deff (& GE; 1.0 x AgGaS2), and beneficial phase-matching (PM) feature are the two major challenges faced in this field. The former can be effectively solved through the combination of local asymmetric units and chemical substi-tution strategy, while for the latter, there is no systematic survey and lack of universally applicable methodology. In this review, 40 IR-NLO chalcogendides are selected based on the aforementioned two challenges and divided into 7 types according to the different chemical components. The composition-structure-performance relation-ships and the theoretical origin of their IR-NLO properties are summarized systematically. At length, some useful information and development prospects were briefly discussed, which may offer new ideas and promote the discovery of IR-NLO materials with the ideal comprehensive performance.

Automated summary

Infrared nonlinear optical (IR-NLO) crystals are attracting attention for their ability to generate coherent tunable IR laser output. Chalcogenides, as a popular branch of IR-NLO materials, show promising second-harmonic generation (SHG) coefficient and broad transmission regions. The challenges in this field include obtaining non-centrosymmetric (NCS) structure and achieving wide energy gap, sufficient deff, and beneficial phase-matching (PM) feature. This review systematically summarizes the composition-structure-performance relationships and theoretical origins of 40 selected IR-NLO chalcogenides, and provides development prospects to discover IR-NLO materials with ideal performance.