Nonlinear epsilon-near-zero material: Explanation with time-varying thermal energy

Abstract

<p indent="0mm">In recent years, transparent conducting oxides with epsilon-near-zero (ENZ) response and their associated applications in nonlinear optics have drawn wide attention of the research community. It is commonly thought that the physical origin of the giant optical nonlinearity in ENZ materials is the large change of effective mass of free electrons within the conduction band of the transparent conducting oxide material. In a recent study, by introducing the concept of time-varying thermal energy, the transient nonlinear optical response of ENZ material is more thoroughly explained. The theory is further corroborated by experimental studies.