One-dimensional surface-plasmon gratings for the excitation of intersubband polaritons in suspended membranes

We present the observation of the strong light–matter coupling regime between intersubband transitions of semiconductor quantum wells and the plasmonic-like resonances of a one dimensional metallic grating. Polariton spectra have been recorded in transmission employing a suspended membrane sample and are consistent with theoretical calculations. This arrangement, avoiding the complexity of dispersive substrate, is particularly attractive for the development of time-resolved pump–probe experiments.