Chalcophosphates: A Treasure House of Infrared Nonlinear Optical Materials

Design and exploratory synthesis of a novel infrared (IR) nonlinear optical (NLO) crystal with excellent overall performance are crucial for the development of the laser industry. Chalcophosphates with wide IR transparent ranges and rich structural diversity provide a broad stage for material designers' unconstrained imagination. Moreover, plenty of chalcophosphates can intrinsically satisfy many crucial criteria for a promising IR NLO crystal, such as a large NLO effect, wide band gap, and low melting point, which makes them a treasure house of IR NLO materials to be explored. The investigation of NLO chalcophosphates began in the last century, and quite a few NLO chalcophosphates with superior performance have been reported. However, the systematic review of this attractive family is still absent. In this Review, we classify the existing NLO chalcophosphates according to their crystal structure characteristics. The structure-performance relationships, application prospects, and future development directions of NLO chalcophosphates are discussed.