The size distribution of Si-nanocrystals(Si-ncs)in evenly annealed SiO is investigated with transmission electron microscopy(TEM),x-ray diffraction(XRD),and Raman scattering.Two groups of Si-ncs with very different mo...The size distribution of Si-nanocrystals(Si-ncs)in evenly annealed SiO is investigated with transmission electron microscopy(TEM),x-ray diffraction(XRD),and Raman scattering.Two groups of Si-ncs with very different most probable diameters are identified,where one is>6nm and the other one is<2nm.Both of them increase gradually with increasing annealing temperature.Such a phenomenon is observed directly by TEM for samples with larger Si-ncs(>10nm)and it can be revealed clearly for all samples by Raman spectra with two components(~500cm^(-1)and~520cm^(-1)).The results of XRD show the average effect.The experimental results indicate that the common assumption of Si-nc size distribution with single most probable diameter is not always proper and the possible mechanisms are briefly discussed.展开更多
A low-threshold Raman effect in a kilowatt ytterbium-doped narrowband fiber amplifier system is reported. The Raman Stokes light at 1120 nm is achieved with the total output power of only N400 W, indicating that the R...A low-threshold Raman effect in a kilowatt ytterbium-doped narrowband fiber amplifier system is reported. The Raman Stokes light at 1120 nm is achieved with the total output power of only N400 W, indicating that the Raman threshold of this kilowatt codireetional pumped continuous wave fiber amplifier is much lower than the predicted value estimated by the classic formula. To figure out the mechanism of this phenomenon, simulations based on the general stimulated Raman scattering （SRS） model are analyzed indicating that the key factor is the coupling between four-wave mixing （FWM） and SRS. The simulation results are in good agreement with our experiments.展开更多
基金Supported in part by the National Basic Research Program of China under Grant Nos 2011CBA00608 and 2007CB307004the National Natural Science Foundation of China under Grant Nos 60877023 and 61036010.
文摘The size distribution of Si-nanocrystals(Si-ncs)in evenly annealed SiO is investigated with transmission electron microscopy(TEM),x-ray diffraction(XRD),and Raman scattering.Two groups of Si-ncs with very different most probable diameters are identified,where one is>6nm and the other one is<2nm.Both of them increase gradually with increasing annealing temperature.Such a phenomenon is observed directly by TEM for samples with larger Si-ncs(>10nm)and it can be revealed clearly for all samples by Raman spectra with two components(~500cm^(-1)and~520cm^(-1)).The results of XRD show the average effect.The experimental results indicate that the common assumption of Si-nc size distribution with single most probable diameter is not always proper and the possible mechanisms are briefly discussed.
基金supported in part by the Shanghai Rising-Star Program (No. 12QH1401100)the Shanghai Natural Science Foundation (No. 11ZR1441400)+1 种基金the NSAF Foundation of National Natural Science Foundation of China (No. U1330134)the Natural Science Foundation of China (No. 61308024)
文摘A low-threshold Raman effect in a kilowatt ytterbium-doped narrowband fiber amplifier system is reported. The Raman Stokes light at 1120 nm is achieved with the total output power of only N400 W, indicating that the Raman threshold of this kilowatt codireetional pumped continuous wave fiber amplifier is much lower than the predicted value estimated by the classic formula. To figure out the mechanism of this phenomenon, simulations based on the general stimulated Raman scattering （SRS） model are analyzed indicating that the key factor is the coupling between four-wave mixing （FWM） and SRS. The simulation results are in good agreement with our experiments.
