  Interface interactions in 2D vertically stacked heterostructures play an
important role in optoe-lectronic applications, photodetectors based on
graphene/InSe heterostructures had shown promising performance nowadays.
However, nonlinear optical properties studies based on the graphene/InSe
heterostructure was insufficient. Here, we fabricated graphene/InSe
heterostruc-ture by mechanical exfoliation, and investigated the optically
induced charge transfer between graphene/InSe heterostructures by taking
photoluminescence and pump-probe measurements. The large built-in electric
field at the interface is confirmed by Kelvin probe force microscopy.
Furthermore, due to the efficient interfacial carrier transfer driven by
built-in electric potential (~ 286 meV) and broadband nonlinear absorption, the
application of graphene/InSe heterostruc-ture in mode-locked laser is realized.
Our work not only provides a deeper understanding for the dipole orientation
related interface interactions on the photoexcited charge transfer of
gra-phene/InSe heterostructure, but also enrich the saturable absorber family
for ultrafast photon-ics application.
