Molecular Radiative Energy Shifts under Strong Oscillating Fields

Abstract Coherent manipulation of light‐matter interactions is pivotal to the advancement of nanophotonics. Conventionally, the non‐resonant optical Stark effect is harnessed for band engineering by intense laser pumping. However, this method is hindered by the transient Stark shifts and the high‐energy laser pumping which, by itself, is precluded as a nanoscale optical source due to light diffraction. As an analog of photons in a laser, surface plasmons are uniquely positioned to coherently interact with matter through near‐field coupling, thereby, providing a potential source of electric fields. Herein, the first demonstration of plasmonic Stark effect is reported and attributed to a newly uncovered energy‐bending mechanism. As a complementary approach to the optical Stark effect, it is envisioned that the plasmonic Stark effect will advance fundamental understanding of coherent light‐matter interactions and will also provide new opportunities for advanced optoelectronic tools, such as ultrafast all‐optical switches and biological nanoprobes at lower light power levels.