Time-dependent damage to fused silica induced by high frequency ultraviolet laser is investigated.Photothermal spectroscopy(PTS) and optical microscopy(OM) are utilized to characterize the evolution of damage pits wit...Time-dependent damage to fused silica induced by high frequency ultraviolet laser is investigated.Photothermal spectroscopy(PTS) and optical microscopy(OM) are utilized to characterize the evolution of damage pits with irradiation time.Experimental results describe that in the pre-damage stage of fused silica sample irradiated by 355-nm laser,the photothermal spectrum signal undergoes a process from scratch to metamorphism due to the absorption of laser energy by defects.During the visible damage stage of fused siliea sample,the photothermal spectrum signal decreases gradually from the maximum value because of the aggravation of the damage and the splashing of the material.This method can be used to estimate the operation lifetime of optical elements in engineering.展开更多
The electronic structure of perfect ammonium dihydrogen phosphate(ADP) and defective ADP with an oxygen(O) vacancy are calculated by screened-exchange hybrid density functional HSE06. The optimized structural paramete...The electronic structure of perfect ammonium dihydrogen phosphate(ADP) and defective ADP with an oxygen(O) vacancy are calculated by screened-exchange hybrid density functional HSE06. The optimized structural parameters of the defective ADP crystal are analyzed. The PO_4 tetrahedron with an O vacancy is distorted and its symmetry is broken. The band gap of the defective ADP with an O vacancy is about 1.5 eV lower than the perfect ADP, which is due to the new O vacancy defect states near the valence band maximum. Moreover, more peaks appear in the low-energy region(lower than 6 eV) in the curves of the linear optical properties for the defective ADP. The results indicate that the O vacancy will significantly influence the laser damage performance of ADP crystals.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51402173)the Fundamental Research Funds for the Central Universities,China(Grant No.FRF-TP-15-099A1).
文摘Time-dependent damage to fused silica induced by high frequency ultraviolet laser is investigated.Photothermal spectroscopy(PTS) and optical microscopy(OM) are utilized to characterize the evolution of damage pits with irradiation time.Experimental results describe that in the pre-damage stage of fused silica sample irradiated by 355-nm laser,the photothermal spectrum signal undergoes a process from scratch to metamorphism due to the absorption of laser energy by defects.During the visible damage stage of fused siliea sample,the photothermal spectrum signal decreases gradually from the maximum value because of the aggravation of the damage and the splashing of the material.This method can be used to estimate the operation lifetime of optical elements in engineering.
基金Supported by the National Natural Science Foundation of China under Grant No 51402173the Fundamental Research Funds for the Central Universities under Grant No FRF-TP-15-099A1the Funding Project of China Scholarship Council under Grant No 201806465071
文摘The electronic structure of perfect ammonium dihydrogen phosphate(ADP) and defective ADP with an oxygen(O) vacancy are calculated by screened-exchange hybrid density functional HSE06. The optimized structural parameters of the defective ADP crystal are analyzed. The PO_4 tetrahedron with an O vacancy is distorted and its symmetry is broken. The band gap of the defective ADP with an O vacancy is about 1.5 eV lower than the perfect ADP, which is due to the new O vacancy defect states near the valence band maximum. Moreover, more peaks appear in the low-energy region(lower than 6 eV) in the curves of the linear optical properties for the defective ADP. The results indicate that the O vacancy will significantly influence the laser damage performance of ADP crystals.
