Super-Mossian Dielectrics for Nanophotonics

摘要

High refractive index dielectrics enable nanoscale integration of optical componentswith practically no absorption loss. Hence, high index dielectrics arepromising for many emerging applications in nanophotonics. However, thelack of a complete library of high index dielectric materials poses a significantchallenge to understanding the full potential for dielectric nanophotonics.Currently, it is assumed that the absorption edge and the sub-bandgap refractiveindex of a semiconductor exhibit a rigid trade-off, popularly known as theMoss rule. Thus, the Moss rule appears to set an upper limit on the refractiveindex of a dielectric for a given operating wavelength. However, thereare many dielectric materials that surpass the Moss rule, referred to here assuper-Mossian dielectrics. Here, the general features of super-Mossian dielectricsand their physical origin are discussed to facilitate the search for highindex dielectrics. As an example, iron pyrite, an outstanding super-Mossianmaterial with index nearly 40% higher than the Moss rule prediction, isdeveloped. The local dielectric resonances in iron pyrite nanoresonators areexperimentally observed, and the impact of super-Mossian materials onnanophotonics is demonstrated.