The Rise of Infrared Nonlinear Optical Pnictides: Advances and Outlooks.

Infrared (IR) nonlinear optical (NLO) materials are the core devices to realize IR laser output, which are of vital importance in civilian and military fields. Non-centrosymmetric chalcogenide and pnictide compounds have already been widely accepted as favorable systems for IR-NLO materials. Compared to the extensively investigated IR-NLO chalcogenides during the past few decades, the research of non-centrosymmetric phosphides as IR-NLO materials is relatively scarce. In this frontier article, the recent progress of pnictides as emerging IR-NLO candidates has been highlighted based on the perspective of new crystal exploration. These IR-NLO pnictides recently reported were divided into three groups from binary to quaternary according to their chemical compositions. The synthetic methods, structural chemistry, and structure-activity relationships are analyzed and summarized in detail. Finally, current problems and the future development of this field are also proposed.
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