Surface enhanced infrared absorption in dielectric thin films with ultra-strong confinement effects

By formulating a microscopic description of the non-local dielectric constant, we have investigated the mechanisms of infrared absorption in dielectrics thin films by molecular dynamics simulations. We found that light absorption in dielectric slabs does not occur predominantly at the polaritons resonances but through anomalous surface modes extremely confined in space. This demonstrates that any macroscopic description of electrodynamics in dielectrics breaks down at the nanoscale.