Progress of Research on New Nonlinear Optical Crystals Ca_4RO(BO_3)_3

The isostructural calcium rare-earth oxyborates Ca_4RO(BO_3)_3 (R-La~3+ I Nd3~+, Sin3~+ ,Gd3~+, Y3~+, Er~3+, Tb~3+, Lu~_3+) as nonlinear optical materials have attracted great attentions recently. They belong to the monoclinic crystallographic system with space group Cm. The progresson the research of their structures and crystal growth was reviewed, and their linear/nonlinearoptical properties and self-frequency doubling properties were also summarized in detail. It wassuggested that these crystals possess potential applications in frequency conversion.