Coherent light radiation down to the deep-ultraviolet spectral range (λ < 200 nm) produced by common laser sources is extensively used in diverse fields ranging from ultrahighresolution photolithography to photochemical synthesis to high precision micro-processing. Actually, it is hard to immediately obtain certain wavelengths, deep-ultraviolet coherent light in particular, from commercial laser sources. However, the direct second harmonic generation process governed in part by nonlinear optical crystals is a feasible and effective approach to generate deep-ultraviolet coherent light, which motivates chemists and materials scientists to find potential deep-ultraviolet nonlinear optical materials that can practically meet the scientific requirements. The research progress required to go from a new single crystal structure to final device applications involves many pivotal steps and is highly time-consuming and challenging, and therefore, it is necessary to commence systematic studies aimed at shortening the research cycle and accelerating the rational design of deep-ultraviolet nonlinear optical materials.

Recently, a research group led by Prof. Shilie Pan at Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Science, has raise three specific rational design strategies to shorten the investigational cycle of discovering the new expected compounds with high physicochemical performances required for practical applications. The review was published in Accounts of Chemical Researchwith title of “targeting the next generation of deep-ultraviolet nonlinear optical materials: expanding from borates to borate fluorides to fluorooxoborates”.

In this review, the progress of searching for candidates for the next generation of deep-ultraviolet nonlinear optical materials was accelerated from borates to borate fluorides to fluorooxoborates with three effective strategies: (1) expansion of the frontier from borates to borate fluorides with the introduction of fluorine to achieve enhanced optical performance; (2) computer-assisted design of new deep-ultraviolet nonlinear optical materials with a newly introduced systematic global structure optimization method; and (3) expansion of the frontier from borate fluorides to fluorooxoborates by proposed functionalized oxyfluoride [BO_xF_4-x]^(x+1)- (x = 1, 2, 3) chromophores to balance multiple criteria. The preliminary development of fluorooxoborates exhibiting high performance as a new fertile field to search for deepultraviolet nonlinear optical materials is highly encouraging and inspiring and can guide chemists and materials scientists with new directions and thoughts aimed at finding the next generation of practical deep-ultraviolet nonlinear optical materials.