Photon upconversion through high harmonic generation,multiphoton absorption,Auger recombination and phonon scattering performs a vital role in energy conversion and renormalization.Considering the reduced dielectric s...Photon upconversion through high harmonic generation,multiphoton absorption,Auger recombination and phonon scattering performs a vital role in energy conversion and renormalization.Considering the reduced dielectric screening and enhanced Coulomb interactions,semiconductor monolayers provide a promising platform to explore photon upconversion at room temperature.Additionally,two-photon upconversion was recently demonstrated as an emerging technique to probe the excitonic dark states due to the extraordinary selection rule compared with conventional excitation.However,highly efficient two-photon upconversion still remains challenging due to the limited multiphoton absorption efficiency and long radiative lifetimes.Here,a 2440-fold enhancement of two-photon luminescence(TPL)is achieved in doubly resonant plasmonic nanocavities due to the amplified light collection,enhanced excitation rate,and increased quantum efficiency.To gain more insight into the attractive doubly resonant enhancement in such a plasmon−exciton coupling system,the intriguing thermally tuned excitonic upconversion and optimized amplification factor>3000 are realized at 350 K.Meanwhile,the single resonance enhanced photoluminescence(PL)(~890-fold)and second-harmonic generation(SHG)(~134-fold)are elaborately demonstrated.These results establish a foundation for developing cost-effective,high-performance nonlinear photonic devices and probing fine excitonic states via configuring plasmonic nanocavities.展开更多
基金supported by the National Science Foundation of China(Grant Nos.12027807,12574418,12104241,62225501)Fundamental Research Funds for the Central Universities(Grant No.075-63253216).
文摘Photon upconversion through high harmonic generation,multiphoton absorption,Auger recombination and phonon scattering performs a vital role in energy conversion and renormalization.Considering the reduced dielectric screening and enhanced Coulomb interactions,semiconductor monolayers provide a promising platform to explore photon upconversion at room temperature.Additionally,two-photon upconversion was recently demonstrated as an emerging technique to probe the excitonic dark states due to the extraordinary selection rule compared with conventional excitation.However,highly efficient two-photon upconversion still remains challenging due to the limited multiphoton absorption efficiency and long radiative lifetimes.Here,a 2440-fold enhancement of two-photon luminescence(TPL)is achieved in doubly resonant plasmonic nanocavities due to the amplified light collection,enhanced excitation rate,and increased quantum efficiency.To gain more insight into the attractive doubly resonant enhancement in such a plasmon−exciton coupling system,the intriguing thermally tuned excitonic upconversion and optimized amplification factor>3000 are realized at 350 K.Meanwhile,the single resonance enhanced photoluminescence(PL)(~890-fold)and second-harmonic generation(SHG)(~134-fold)are elaborately demonstrated.These results establish a foundation for developing cost-effective,high-performance nonlinear photonic devices and probing fine excitonic states via configuring plasmonic nanocavities.
