Nanoscale All-Solid-State Plasmochromic Waveguide Nonresonant Modulator.

Plasmochromics, the interaction of plasmons with an electrochromic material, have spawned a new class of active plasmonic devices. By introducing electrochromic materials into the plasmon's dielectric environment, plasmons can be actively manipulated. We introduce inorganic WO3 and ion conducting LiNbO3 layers as the core materials in a solid-state plasmochromic waveguide (PCWG) to demonstrate light modulation in a nanoplasmonic waveguide. The PCWG takes advantage of the high plasmonic loss at the high field located at the WO3/Au interface, where the Li+ ions are intercalated into a thin WO3 plasmon modulating layer. Through careful PCWG design, the direction for ion diffusion and plasmon propagation are decoupled, leading to enhanced modulation depth and fast EC switching times. We show that at a bias voltage of 2.5 V, the fabricated PCWG modulator achieves modulation depths as high as 20 and 38 dB for 10 and 20 μm long devices, respectively.