Compared with powdered phosphors used for LEDs, transparent glasses exhibit many advantages, such as lower production cost, better thermal stability,epoxy-resin-free assembly process, and wide range for microstructure design.Investigation into photoluminescence properties of amorphous glass phosphors for LEDs has been carried out extensively, but it was mainly limited to rare-earth (RE) ions activated glasses.However, RE ions with parity forbidden f-f transitions cannot be efficiently pumped by UV-light due to their small absorption cross sections.It is notable that glasses containing ns2-type (n ≥ 4) emission centers, such as Sn2+, Bi3+,Sb3+, Tl+, Pb2+ and Hg0, have attracted considerable attention recently due to strong photoluminescence (PL) properties for the parity allowed transitions.Moreover, the emission enhancements of activators, such as RE ions, are expected to introduce the ns2-type cations as efficient sensitizers.However, the emission mechanisms of the high-light output are not totally identified in Sn2+-doped oxide glasses.In this work,the emission properties of ns2-type Sn2+ emission centers were demonstrated in CaO-B2O3-SiO2 glasses.The broad excitation bands, which are assumed to be composed of S1 and S2 sub-bands, correlate strongly with Sn2+ doping content.The blue Sn2+ emission bands can be tailored by tuning Sn2+ coordinate field.Significant enhancement of Sn2+ emission was observed in B2O3-rich glasses.