摘要
Achieving strong coupling between plasmonic oscillators can significantly modulate their intrinsic optical properties.Here,we report the direct observation of ultrafast plasmonic hot electron transfer from an Au grating array to an MoS_(2) monolayer in the strong coupling regime between localized surface plasmons(LSPs)and surface plasmon polaritons(SPPs).By means of femtosecond pump-probe spectroscopy,the measured hot electron transfer time is approximately 40 fs with a maximum external quantum yield of 1.65%.Our results suggest that strong coupling between LSPs and SPPs has synergetic effects on the generation of plasmonic hot carriers,where SPPs with a unique nonradiative feature can act as an‘energy recycle bin’to reuse the radiative energy of LSPs and contribute to hot carrier generation.Coherent energy exchange between plasmonic modes in the strong coupling regime can further enhance the vertical electric field and promote the transfer of hot electrons between the Au grating and the MoS_(2) monolayer.Our proposed plasmonic strong coupling configuration overcomes the challenge associated with utilizing hot carriers and is instructive in terms of improving the performance of plasmonic opto-electronic devices.
基金
supported by the National Key Research and Development Program of China(Grant No.2017YFA0205700)
National Basic Research Program of China(Grant Nos.2015CB932403,2017YFA0206000)
National Science Foundation of China(Grant Nos.11674012,61422501,11374023,61521004 and 21790364)
Beijing Natural Science Foundation(Grant No.L140007)
Foundation for the Author of National Excellent Doctoral Dissertation of PR China(Grant No.201420)
National Program for Support of Top-notch Young Professionals(Grant No.W02070003)
Ministry of Education Singapore under Grant No.MOE2015-T2-2-043.