Nonlinear Self-Confined Plasmonic Beams: Experimental Proof

Controlling low power light beam self-confinement with ultrafast response time opens up opportunities for the development of signal processing in microdevices. The combination of a highly nonlinear medium with the tight confinement of plasmonic waves offers a viable but challenging configuration to reach this goal. In the present work, a beam propagating in a plasmonic structure that undergoes a strongly enhanced self-focusing effect is reported for the first time. The structure consists of a chalcogenide-based four-layer planar geometry engineered to limit plasmon propagation losses while exhibiting efficient Kerr self-focusing at moderate power. As expected from theory, only TM-polarized waves exhibit such a behavior. Different experimental arrangements are tested at telecom wavelengths and compared with simulations obtained from a dedicated model. The observed efficient beam reshaping takes place over a distance as low as 100 μm, which unlocks new perspectives for the development of integrated photonic devices.