Passive optical switches based on endohedral fullerenes

• Low optical limiting thresholds (<0.3 mJ/cm2) achieved in endohedral fullerenes.
• The nature of trimetallic nitride is critical to tuning the HOMO–LUMO gap.
• Endohedral fullerenes exhibit optical limiting similar to realistic optical switch.

Reverse saturable absorption in fullerenes has been widely used to realize excellent passive optical limiters for the visible region up to 650 nm. However, there is still a need for passive optical switches and limiters with a low limiting threshold (<0.5 J/cm2) and higher damage limits. The electronic structure of fullerenes can be modified either through doping or by the encapsulation of endohedral clusters to achieve exotic quantum states of matter such as superconductivity. Building on this ability, we show that the encapsulation of Sc3N, Lu3N or Y3N in C80 alters the HOMO–LUMO gap and leads to passive optical switches with a significantly low limiting threshold (0.3 J/cm2) and a wider operation window (average pulse energy >0.3 mJ in the ns regime).