Unidirectional Scattering of Surface Plasmon Polaritons at the Interface of Indium-Tin-oxide Coated Fe-doped LiNbO3

We demonstrated, both experimentally and theoretically, surface plasmon polaritons (SPPs) can be unidirectionally scattered at the interface of indium-tin-oxide (ITO) coated iron doped Y-cut lithium niobate (Fe:LiNbO3, Fe:LN) slab. The multipole analysis referring to the spontaneous polarization was utilized to introduce an asymmetry to the Fe:LN/ITO system. Furthermore, with strong bulk photovoltaic effect of Fe:LN, the diffusion mechanism of space charge transport brought local and nonlocal responses to the scattering process, leading to the unidirectional scattering of SPPs. This work opens an opportunity in designing ultracompact integrated plasmonic circuits without needs to resort to lossy metals.