PNNL

Abstract

A simple and robust approach to visualization of terahertz (THz) light would open up opportunities to couple physical phenomena that occur at fundamentally different energy scales. Here we demonstrate how nanoscale cages of Ca12Al14O33 crystal enable a novel method for conversion THz radiation to visible light. These crystallographic cages contain weakly bonded oxygen ions and give rise to a low-energy conduction band that can populated with localized yet mobile electrons. THz light excites a nearly stand-alone rattling motion of the encaged species, which promotes electron transfer from them to the neighboring cages. When the power of THz light reaches tens of watts, the coupling between forced rattling in the confined space, electronic excitation and ionization of oxygen species and corresponding recombination processes result in emission of bright visible light.