Controllable coherent absorption of counterpropagating laser beams in organic microcavities

Abstract

We investigate coherent perfect absorption in a microcavity with C₆₀ as an organic absorbing material. The experiment consists of a two-beam setup of counterpropagating laser beams incident on a single sample from opposite sides, resulting in two counterpropagating outputs consisting of the reflected and transmitted parts of the incident beams. The systematic behavior of the output intensities as a function of the relative phase of incident beams and the thickness of the absorbing cavity layer is investigated. We experimentally verify that the absorption resonance of the cavity is accompanied by a transition of the phase difference of the individual outputs, which is characterized by a passage from out-of-phase to in-phase behavior of the outputs for varying relative phases of incident beams. The analysis shows that the amplitudes and offsets of the outputs qualitatively follow the theoretical model.