Near Field Optical-Pump-Terahertz-Probe Experiments on Graphene/InAs Heterostructure

We show that graphene is a perfect terahertz reflector in the high q regime with terahertz s-SNOM. We also demonstrate optical pump terahertz near-field probe (n-OPTP) and optical pump terahertz near field emission (n-OPTE) experiments on graphene/InAs heterostructure. Femtosecond pulse laser is used to both pump samples and to generate terahertz pulses. We show that in the near-field regime a single layer graphene is transparent to near-IR (800 nm) optical excitated terahertz emission from InAs but completely “screens” the photo-induced carrier dynamics in InAs probed by a seperate THz pulse.