title: Observing the interplay between surface and bulk optical nonlinearities in thin van der Waals crystals.
abstract: Van der Waals materials, existing in a range of thicknesses from monolayer to bulk, allow for interplay between surface and bulk nonlinearities, which otherwise dominate only at atomically-thin or bulk extremes, respectively. Here, we observe an unexpected peak in intensity of the generated second harmonic signal versus the thickness of Indium Selenide crystals, in contrast to the quadratic increase expected from thin crystals. We explain this by interference effects between surface and bulk nonlinearities, which offer a new handle on engineering the nonlinear optical response of 2D materials and their heterostructures.
authors.affiliation: Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Japan.
authors.forename: Skylar
authors.initials: S
authors.lastname: Deckoff-Jones
authors.affiliation: Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Japan.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Japan.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Petoukhoff
authors.affiliation: Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Japan.
authors.forename: Michael K L
authors.initials: MK
authors.lastname: Man
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas, 77005, USA.
authors.forename: Sidong
authors.initials: S
authors.lastname: Lei
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas, 77005, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Vajtai
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas, 77005, USA.
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan
authors.affiliation: Department of Physics and Engineering Physics, Tulane University, 6400 Freret Street, New Orleans, Louisiana 70118, US.
authors.forename: Diyar
authors.initials: D
authors.lastname: Talbayev
authors.affiliation: Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Japan.
authors.forename: Julien
authors.initials: J
authors.lastname: Madéo
authors.affiliation: Femtosecond Spectroscopy Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Japan.
authors.forename: Keshav M
authors.initials: KM
authors.lastname: Dani