Bloch Surface Wave-Assisted Ultrafast All-Optical Switching in Graphene

Graphene has ultrafast charge carrier dynamic and shows strong light-matter interaction allowing the use in photovoltaic devices, fast photodetectors, saturable absorbers, and electro-optical modulators. However, despite the high nonlinear optical susceptibilities, the small amount of material significantly limits the use of graphene for nonlinear optical applications. In this work, Bloch surface waves (BSWs) are employed, enhancing the graphene-light interaction, for all-optical switching realization. By placing a graphene monolayer on top of a 1D photonic crystal, it is shown that for the wavelength corresponding to the BSW resonance, the reflection coefficient is modulated on the sub-picosecond time scale by an order of magnitude larger than that for bare graphene. The magnitude of the reflection change reaches 0.3% at the fluence of 40 mu J cm(-2). The reported results are proof of priciple possibility of BSW-assisted enhancing the reflection modulation of any 2D materials and transparent thin films while maintaining their inherent ultrafast dynamics, which is useful for the further development of all-optical switches.