There are extensive studies to date on optical nonlinearities in microcavities at the near and mid-IR wavelengths.Pushing this research into the visible region is equally valuable.Here,we demonstrate a directly pumped...There are extensive studies to date on optical nonlinearities in microcavities at the near and mid-IR wavelengths.Pushing this research into the visible region is equally valuable.Here,we demonstrate a directly pumped,blue band Kerr frequency comb and stimulated Raman scattering(SRS)at 462 nm in a silica nanofiber-coupled whispering gallery microcavity system.Notably,due to the high optical intensities achieved,photodarkening is unavoidable and can quickly degrade the optical quality of both the coupling optical nanofiber and the microcavity,even at very low pump powers.Nonetheless,stable hyperparametric oscillation and SRS are demonstrated in the presence of photodarkening by taking advantage of in-situ thermal bleaching.This work highlights the challenges of silica-based,short wavelength nonlinear optics in high-quality,small mode volume devices and gives an effective method to overcome this apparent limitation,thus providing a baseline for optics research in the blue region for any optical devices fabricated from silica.展开更多
The re moval efficiency of pollutants in Fe(O) electrocoagulation(EC) has been associated closely with the speciation of generated Fe(Ⅱ)/Fe(Ⅲ) oxides during this process,which is very complicated and can be affected...The re moval efficiency of pollutants in Fe(O) electrocoagulation(EC) has been associated closely with the speciation of generated Fe(Ⅱ)/Fe(Ⅲ) oxides during this process,which is very complicated and can be affected by various factors.In this work,in-situ Raman,X-ray diffraction and some other techniques have been used to study the speciation of Fe under different conditions and to establish a relationship between Fe speciation and Sb(V) removal efficiency.Results indicated that concentration of dissolved oxygen(DO)is a key factor influencing Fe(O) EC.It was found that green rusts(GRs) were formed and were then transformed into magnetite at lower DO concentration,and Sb(V) removal efficiency reached 99.9% after30 min of EC.In contrast,γ-FeOOH was formed at high DO concentration,and the removal efficiency of Sb(V) after 30 min of EC was only 72.8%.In the presence of sulfite and phosphate with low concentrations,GRs can be stabilized and benefit the removal of Sb(V).We believe this work will provide some new insights on the mechanism of Fe(O) EC and the effective removal of other pollutants during Fe(O)EC process.展开更多
基金Okinawa Institute of Science and Technology Graduate UniversityChina Scholarship Council(201906680)+1 种基金Harbin Engineering University Scholarship FundJSPS Grant-in-Aid for Early-Career Scientists(Kakenhi)(22K14621)。
文摘There are extensive studies to date on optical nonlinearities in microcavities at the near and mid-IR wavelengths.Pushing this research into the visible region is equally valuable.Here,we demonstrate a directly pumped,blue band Kerr frequency comb and stimulated Raman scattering(SRS)at 462 nm in a silica nanofiber-coupled whispering gallery microcavity system.Notably,due to the high optical intensities achieved,photodarkening is unavoidable and can quickly degrade the optical quality of both the coupling optical nanofiber and the microcavity,even at very low pump powers.Nonetheless,stable hyperparametric oscillation and SRS are demonstrated in the presence of photodarkening by taking advantage of in-situ thermal bleaching.This work highlights the challenges of silica-based,short wavelength nonlinear optics in high-quality,small mode volume devices and gives an effective method to overcome this apparent limitation,thus providing a baseline for optics research in the blue region for any optical devices fabricated from silica.
基金the National Key R&D Program of China(No.2016YFC0401405)National Natural Science Foundation of China(No.51808512)。
文摘The re moval efficiency of pollutants in Fe(O) electrocoagulation(EC) has been associated closely with the speciation of generated Fe(Ⅱ)/Fe(Ⅲ) oxides during this process,which is very complicated and can be affected by various factors.In this work,in-situ Raman,X-ray diffraction and some other techniques have been used to study the speciation of Fe under different conditions and to establish a relationship between Fe speciation and Sb(V) removal efficiency.Results indicated that concentration of dissolved oxygen(DO)is a key factor influencing Fe(O) EC.It was found that green rusts(GRs) were formed and were then transformed into magnetite at lower DO concentration,and Sb(V) removal efficiency reached 99.9% after30 min of EC.In contrast,γ-FeOOH was formed at high DO concentration,and the removal efficiency of Sb(V) after 30 min of EC was only 72.8%.In the presence of sulfite and phosphate with low concentrations,GRs can be stabilized and benefit the removal of Sb(V).We believe this work will provide some new insights on the mechanism of Fe(O) EC and the effective removal of other pollutants during Fe(O)EC process.
