Employing 0.3 nm diameter single-walled carbon nanotubes（SWCNTs）as saturable absorbers,we demonstrate a passively mode-locked fiber laser operating at 1950 nm.The 0.3 nm diameter SWCNTs are prepared by pyrolyzing di...Employing 0.3 nm diameter single-walled carbon nanotubes（SWCNTs）as saturable absorbers,we demonstrate a passively mode-locked fiber laser operating at 1950 nm.The 0.3 nm diameter SWCNTs are prepared by pyrolyzing dipropylamine in the channels of zeolite crystals Mg APO-11（AEL）.The laser pumped by a 1550 nm laser source produces 972 fs pulses with a spectral width at half-maximum of 4.2 nm and a repetition rate of 21.05 MHz,an average output power of 2.3 mW corresponding to the maximum pump power of 420 mW with a 10%output coupler.展开更多
Controllable formation of microstructures in the assembled graphene film could tune the physical properties and broaden its applications in flexible electronics.Many efforts have been made to control the formation of ...Controllable formation of microstructures in the assembled graphene film could tune the physical properties and broaden its applications in flexible electronics.Many efforts have been made to control the formation of wrinkles and ripples in graphene films.However,the formation of orderly wrinkles in graphene film remains a challenge.Here,we reported a simple strategy for the fabrication of graphene film with periodic and parallel wrinkles with a pre-stretched polydimethylsiloxane substrate.The width of the wrinkles in graphene can be controlled by changing the pre-stretched strain of the substrate.The average width of wrinkles in graphene film on the substrate with pre-stretched strain of 10%,20%,and 50%was about 3.68,2.99 and 2.01µm,respectively.The morphological evolution of wrinkled double-layered graphene under mechanical deformation was observed and studied.Furthermore,a strain sensor was constructed based on the wrinkled graphene,showing high sensitivity,large working range and excellent cyclic stability.These strain sensors show great potential in real-time motion detection,health surveillance and electronic skins.展开更多
用分子束外延设备在c面蓝宝石衬底上生长得到高质量Mg x Zn1-x O薄膜。X射线衍射显示,当Mg摩尔分数在0~32.7%范围内时,薄膜保持六方结构,(002)衍射峰半高宽为0.08°~0.12°,薄膜结晶质量与现有报道的最高水平相当。随着薄膜中M...用分子束外延设备在c面蓝宝石衬底上生长得到高质量Mg x Zn1-x O薄膜。X射线衍射显示,当Mg摩尔分数在0~32.7%范围内时,薄膜保持六方结构,(002)衍射峰半高宽为0.08°~0.12°,薄膜结晶质量与现有报道的最高水平相当。随着薄膜中Mg含量的增加,紫外发光峰由378 nm蓝移至303 nm。对Mg0.108Zn0.892O薄膜变温光致发光光谱的研究发现,束缚激子发光随温度变化存在两个不同的猝灭过程。对不同Mg含量薄膜共振拉曼光谱的研究发现,A1(LO)声子模频移与Mg含量在一定范围内呈线性关系,这为确定Mg x Zn1-x O薄膜中的Mg含量提供了一种简单高效的方法。通过拉曼光谱与X射线衍射对比研究发现,拉曼光谱在确定MgZnO材料相变时具有更高的灵敏度。最后,研究了Mg0.057Zn0.943O薄膜的变温共振拉曼光谱,对A1(LO)和A1(2LO)声子模随温度而变化的现象给出了一定的理论解释。展开更多
Organic-inorganic hybrid two-dimensional(2D)ruddlesden-popper(RP)perovskites with fantastic optoelectronic properties and good stability have attracted tremendous attention for the potential applications in photovolta...Organic-inorganic hybrid two-dimensional(2D)ruddlesden-popper(RP)perovskites with fantastic optoelectronic properties and good stability have attracted tremendous attention for the potential applications in photovoltaics and electroluminescence.Recently,a new allinorganic Cs2PbI2Cl22D perovskite has been proposed with excellent excitonic absorption and improved ambient and thermal stability.Herein,an interesting light-induced phase transition and photochromism in the Cs2PbI2Cl2were reported.Under low fluence light pumping,the room temperature photoluminescence(PL)of Cs2PbI2Cl2is dominated by a weak violet excitonic emission peaked at 412 nm.Surprisingly,the emission color gradually changes from violet to bright red while increasing the laser pumping fluence.This photochromic effect is determined to be caused by forming CsPbI3phase within the Cs2PbI2Cl2crystals,which is efficiently driven by thermal energy.Due to protection by the Cs2PbI2Cl2matrix,the embedded CsPbI3nanocrystals show improved stability than standard pure CsPbI3.Therefore,the Cs2PbI2Cl2perovskite with photochromic feature may find applications in optical encryption,as preliminarily shown in this work.展开更多
Stable nitrogen doping is an important issue in p-type ZnO research for device applications.In this paper,beryllium and magnesium are systematically compared as a dopant in ZnO to reveal their nitrogen-stabilizing abi...Stable nitrogen doping is an important issue in p-type ZnO research for device applications.In this paper,beryllium and magnesium are systematically compared as a dopant in ZnO to reveal their nitrogen-stabilizing ability.Secondary ion mass spectrum shows that Be and Mg can both enhance the stability of nitrogen in ZnO while Be has a better performance.Zn 2p and O 1s electron binding energies change in both MgZnO and Be ZnO thin films.Donor-acceptor luminescence is observed in the BeZnO samples.We conclude that Be is a better co-doping element than Mg for p-type ZnO：N.展开更多
基金supported by the National Natural Science Foundation of China(No.61275144)the Shenzhen Science and Technology Project(Nos.JCYJ20150525092941038 and JCYJ20140418091413577)
文摘Employing 0.3 nm diameter single-walled carbon nanotubes（SWCNTs）as saturable absorbers,we demonstrate a passively mode-locked fiber laser operating at 1950 nm.The 0.3 nm diameter SWCNTs are prepared by pyrolyzing dipropylamine in the channels of zeolite crystals Mg APO-11（AEL）.The laser pumped by a 1550 nm laser source produces 972 fs pulses with a spectral width at half-maximum of 4.2 nm and a repetition rate of 21.05 MHz,an average output power of 2.3 mW corresponding to the maximum pump power of 420 mW with a 10%output coupler.
基金This work was financially supported by the National Natural Science Foundation of China(51772335)the Science and Technology Program of Guangzhou(201904010450).
文摘Controllable formation of microstructures in the assembled graphene film could tune the physical properties and broaden its applications in flexible electronics.Many efforts have been made to control the formation of wrinkles and ripples in graphene films.However,the formation of orderly wrinkles in graphene film remains a challenge.Here,we reported a simple strategy for the fabrication of graphene film with periodic and parallel wrinkles with a pre-stretched polydimethylsiloxane substrate.The width of the wrinkles in graphene can be controlled by changing the pre-stretched strain of the substrate.The average width of wrinkles in graphene film on the substrate with pre-stretched strain of 10%,20%,and 50%was about 3.68,2.99 and 2.01µm,respectively.The morphological evolution of wrinkled double-layered graphene under mechanical deformation was observed and studied.Furthermore,a strain sensor was constructed based on the wrinkled graphene,showing high sensitivity,large working range and excellent cyclic stability.These strain sensors show great potential in real-time motion detection,health surveillance and electronic skins.
文摘用分子束外延设备在c面蓝宝石衬底上生长得到高质量Mg x Zn1-x O薄膜。X射线衍射显示,当Mg摩尔分数在0~32.7%范围内时,薄膜保持六方结构,(002)衍射峰半高宽为0.08°~0.12°,薄膜结晶质量与现有报道的最高水平相当。随着薄膜中Mg含量的增加,紫外发光峰由378 nm蓝移至303 nm。对Mg0.108Zn0.892O薄膜变温光致发光光谱的研究发现,束缚激子发光随温度变化存在两个不同的猝灭过程。对不同Mg含量薄膜共振拉曼光谱的研究发现,A1(LO)声子模频移与Mg含量在一定范围内呈线性关系,这为确定Mg x Zn1-x O薄膜中的Mg含量提供了一种简单高效的方法。通过拉曼光谱与X射线衍射对比研究发现,拉曼光谱在确定MgZnO材料相变时具有更高的灵敏度。最后,研究了Mg0.057Zn0.943O薄膜的变温共振拉曼光谱,对A1(LO)和A1(2LO)声子模随温度而变化的现象给出了一定的理论解释。
基金supported by the Macao Science and Technology Development Fund(FDCT-116/2016/A3,FDCT-091/2017/A2,FDCT-014/2017/AMJ and FDCT-199/2017/A3)Start-up Research Grant Fund from University of Macao(SRG2016-00002-FST)+3 种基金Research and Development Grant for Chair Professor Fund from University of Macao(CPG2018-00026-FST)Research Grant(SRG201600087-FST,MYRG2018-00148-IAPME and MYRG2018-00142-IAPME)from University of Macaothe National Natural Science Foundation of China(91733302,61935017 and 61605073)the Natural Science Foundation of Guangdong Province of China(2019A1515012186)。
文摘Organic-inorganic hybrid two-dimensional(2D)ruddlesden-popper(RP)perovskites with fantastic optoelectronic properties and good stability have attracted tremendous attention for the potential applications in photovoltaics and electroluminescence.Recently,a new allinorganic Cs2PbI2Cl22D perovskite has been proposed with excellent excitonic absorption and improved ambient and thermal stability.Herein,an interesting light-induced phase transition and photochromism in the Cs2PbI2Cl2were reported.Under low fluence light pumping,the room temperature photoluminescence(PL)of Cs2PbI2Cl2is dominated by a weak violet excitonic emission peaked at 412 nm.Surprisingly,the emission color gradually changes from violet to bright red while increasing the laser pumping fluence.This photochromic effect is determined to be caused by forming CsPbI3phase within the Cs2PbI2Cl2crystals,which is efficiently driven by thermal energy.Due to protection by the Cs2PbI2Cl2matrix,the embedded CsPbI3nanocrystals show improved stability than standard pure CsPbI3.Therefore,the Cs2PbI2Cl2perovskite with photochromic feature may find applications in optical encryption,as preliminarily shown in this work.
基金Project supported by the National Key Basic Research Program of China(Grant No.2011CB302000)the National Natural Science Foundation of China(Grant Nos.51232009 and 51202299)+2 种基金the Fundamental Research Funds for the Central Universities,China(Grant No.11lgpy16)the Natural Science Foundation for Jiangsu Provincial Higher Education,Institutions of China(Grant No.15KJB510005)the Talent Fund of Jiangsu University,China(Grant No.15JDG042)
文摘Stable nitrogen doping is an important issue in p-type ZnO research for device applications.In this paper,beryllium and magnesium are systematically compared as a dopant in ZnO to reveal their nitrogen-stabilizing ability.Secondary ion mass spectrum shows that Be and Mg can both enhance the stability of nitrogen in ZnO while Be has a better performance.Zn 2p and O 1s electron binding energies change in both MgZnO and Be ZnO thin films.Donor-acceptor luminescence is observed in the BeZnO samples.We conclude that Be is a better co-doping element than Mg for p-type ZnO：N.
