Two-photon absorption induced dangling bonds in amorphous silica revealed by molecular dynamics simulations

•The dangling bonds were created by TPA induced (Si-O)3 ring openning process, where the TPA coefficient was calculated by Keldysh formula.•TPA aids in the early formation of dangling bonds, while the densification of a-silica depresses the formation of Frekel-type defcts.•TPA induced (Si-O) bond cleavage is the primary source of ODC defects, and the previous TPA induced Frenkel-type defects in turn contribute to further formation of ODC(I).