Tuning surface plasmon-exciton coupling via thickness controlling of excitonic layer

We present the Rabi energy tuning effects in strong coupling effects between surface plasmon (SP) and exciton in the Kretschmann-Raether configuration by varying excitonic layer thickness. Both experimental results and theoretical calculations indicate that the anticross-like dispersion relation comes from the rapid change of permittivity near the exciton state and can be attributed to the strong coupling between SP and exciton. Our findings reveal that the excitonic layer plays a key role in the SP-exciton coupling. The increase of the excitonic layer will not only enlarge the Rabi splitting energy, but also cause the redshift of SP dispersion relation. Thus to fulfill the coupling condition, there is a critical thickness of the excitonic layer at specific incident angle (theta(inc) < 90 degrees). With the increase of excitonic layer thickness, the Rabi energy increases monotonously and tends to saturate. Our findings will be beneficial for the better understanding of SP-exciton strong coupling in KR configuration and can be useful in tuning the Rabi energy and resonant conditions according to practical applications. Copyright (C) 2021 EPLA