Fast modulation of surface plasmons based on the photothermal effect of nonvolatile solid thin films.

Nonvolatile phase change materials owing to their robust stability and reversibility have shown significant potential in nanophotonic switches and memory devices. However, their performances deteriorate as the thickness decreases below 10 nm due to the local deformation induced by the phase change, which makes them less compatible with plasmonic nanogaps. Here, we address this issue by photothermally modulating the refractive index of germanium antimony telluride (GST) placed in plasmonic nanogaps, which tunes plasmon resonances in the visible region below the melting point of GST, making such optical switching highly reversible at a rate of up to hundreds of ∼kHz. They are also demonstrated to modulate the waveguiding efficiency of propagating surface plasmons, which is based on the photothermal modulation of plasmons with the assistance of GST. Such hybrid nanoplasmonic system with cost-effective fabrication and efficient operation method provides a promising route towards integrated nanophotonic chips.