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 WO 3 and ion conducting LiNbO 3 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 WO 3 /Au interface, where the Li + ions are intercalated into a thin WO 3 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.

The generation of terahertz (THz) radiation in a compact geometry is crucial for the implementation of on-chip, coherent THz radiation sources. Here, via numerical time-domain simulations, we show that LiNbO (LN) waveguides having sub-wavelength core widths can provide highly efficient optical-to-THz radiation frequency conversion over short lengths. By exploiting the nonlinear susceptibility, χ33(2), enhancement of LN near its phonon reststrahlen band and utilizing THz leaky-mode guidance to minimize reststrahlen band absorption and improve phase matching, we show that broadband (0.2-11.6 THz) electric field pulses of 3.4 kV/cm can be generated at an optical-to-THz conversion efficiency of 2.5×10. These sub-wavelength leaky-mode waveguides provide a compact platform for wideband, coherent THz radiation sources.

The backward difference frequency generation process is used to produce narrowband terahertz radiation via modal phase-matching in a S i O 2 - L i N b O 3 -air planar waveguide. The T M 0 pump mode, T E 0 signal mode, and T E 0 or T E 2 idler modes are selected to satisfy the backward difference frequency generation phase-matching condition, thus allowing narrowband (i.e.,  <2017