摘要
Vacuum ultraviolet(VUV)lasers have demonstrated great potential as the light source for various spectroscopies,which,if they can be focused into a small beam spot,will not only allow investigation of mesoscopic materials and structures but also find application in the manufacture of nano-objects with excellent precision.In this work,we report the construction of a 177 nm VUV laser that can achieve a record-small(〜0.76 μm)focal spot at a long focal length(~45 mm)by using a flat lens without spherical aberration.The size of the beam spot of this VUV laser was tested using a metal grating and exfoliated graphene flakes,and we demonstrated its application in a fluorescence spectroscopy study on pure and Tm3+-doped NaYF4 microcrystals,revealing a new emission band that cannot be observed in the traditional up-conversion process.In addition,this laser system would be an ideal light source for spatially and angleresolved photoemission spectroscopy.
基金
C.Z.,L.Y.,and K.H.acknowledge support from the National Natural Science Foundation of China(grants 11774427,61875181,61705085,11774190,and 11427903)
Y.C.acknowledges support from the Engineering and Physical Sciences Research Council Platform(grant EP/M020517/1)
K.H.thanks USTC Research Funds of the Double Rrst-Class Initiative(grant YD2030002003)
"the Fundamental Research Funds for the Central Universities"in China,the CAS Pioneer Hundred Talents Program,and the support from the University of Science and Technology of China’s Centre for Micro and Nanoscale Research and Fabrication.
