Mechanical exfoliation(ME) and chemical vapor deposition(CVD) MoS2 monolayers have been extensively studied, but the large differences of nonlinear optical performance between them have never been clarified. Here,we p...Mechanical exfoliation(ME) and chemical vapor deposition(CVD) MoS2 monolayers have been extensively studied, but the large differences of nonlinear optical performance between them have never been clarified. Here,we prepared MoS2 monolayers using ME and CVD methods and investigated the two-photon absorption(TPA)response and its saturation. We found that the TPA coefficient of the ME monolayer was about(1.88 ± 0.21)× 10^3 cm/GW, nearly two times that of the CVD one at(1.04 ± 0.15)× 10^3 cm/GW. Furthermore,we simulated and compared the TPA-induced optical pulse modulation in multilayer cascaded structures, which is instructive and meaningful for the design of optical devices such as a beam shaper and optical limiter.展开更多
Questions hovering over the modulation of bandgap size and excitonic effect on nonlinear absorption in twodimensional transition metal dichalcogenides (TMDCs) have restricted their application in micro/nano optical mo...Questions hovering over the modulation of bandgap size and excitonic effect on nonlinear absorption in twodimensional transition metal dichalcogenides (TMDCs) have restricted their application in micro/nano optical modulator, optical switching, and beam shaping devices. Here, degenerate two-photon absorption (TPA) in the near-infrared region was studied experimentally in mechanically exfoliated MoS2 from single layer to multilayer. The layer-dependent TPA coefficients were significantly modulated by the detuning of the excitonic dark state (2p). The shift of the quasiparticle bandgap and the decreasing of exciton binding energy with layers were deduced, combined with the non-hydrogen model of excitons in TMDCs and the scaling rule of semiconductors. Our work clearly demonstrates the layer modulation of nonlinear absorption in TMDCs and provides support for layer-dependent nonlinear optical devices, such as optical limiters and optical switches.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.61675217 and 11874370)the Strategic Priority Research Program of CAS(No.XDB16030700)+4 种基金the Key Research Program of Frontier Science of CAS(No.QYZDB-SSW-JSC041)the Program of Shanghai Academic Research Leader(No.17XD1403900)the Natural Science Foundation of Shanghai(No.18ZR1444700)the Shanghai Rising-Star Program(A Type 19QA1410000)the Youth Innovation Promotion Association,CAS
文摘Mechanical exfoliation(ME) and chemical vapor deposition(CVD) MoS2 monolayers have been extensively studied, but the large differences of nonlinear optical performance between them have never been clarified. Here,we prepared MoS2 monolayers using ME and CVD methods and investigated the two-photon absorption(TPA)response and its saturation. We found that the TPA coefficient of the ME monolayer was about(1.88 ± 0.21)× 10^3 cm/GW, nearly two times that of the CVD one at(1.04 ± 0.15)× 10^3 cm/GW. Furthermore,we simulated and compared the TPA-induced optical pulse modulation in multilayer cascaded structures, which is instructive and meaningful for the design of optical devices such as a beam shaper and optical limiter.
基金Strategic Priority Research Program of CAS(XDB16030700)Program of Shanghai Academic Research Leader(17XD1403900)+7 种基金Natural Science Foundation of Shanghai(18ZR1444700)Youth Innovation Promotion Association of the Chinese Academy of SciencesNational Natural Science Foundation of China(NSFC)(11874370,61675217,61875213)Shanghai Rising-Star Program(19QA1410000)CAS Interdisciplinary Innovation Team and National Natural Science Foundation of China(11535010)CAS Center for Excellence in Ultra-Intense Laser ScienceKey Research Program of Frontier Science of CAS(QYZDB-SSW-JSC041)President’s International Fellowship Initiative(PIFI)of CAS(2017VTA0010,2017VTB0006,2018VTB0007)
文摘Questions hovering over the modulation of bandgap size and excitonic effect on nonlinear absorption in twodimensional transition metal dichalcogenides (TMDCs) have restricted their application in micro/nano optical modulator, optical switching, and beam shaping devices. Here, degenerate two-photon absorption (TPA) in the near-infrared region was studied experimentally in mechanically exfoliated MoS2 from single layer to multilayer. The layer-dependent TPA coefficients were significantly modulated by the detuning of the excitonic dark state (2p). The shift of the quasiparticle bandgap and the decreasing of exciton binding energy with layers were deduced, combined with the non-hydrogen model of excitons in TMDCs and the scaling rule of semiconductors. Our work clearly demonstrates the layer modulation of nonlinear absorption in TMDCs and provides support for layer-dependent nonlinear optical devices, such as optical limiters and optical switches.
