title: Nonlinear absorption tuning by composition control in bimetallic plasmonic nanoprism arrays.
abstract: The nonlinear absorption properties of bidimensional arrays of Au-Ag bilayered nanoprisms have been investigated by z-scan measurements as a function of the bimetallic nanoprism composition. A tunable ps laser system was used to excite the ultrafast, electronic nonlinear response matching the laser wavelength with the quadrupolar surface plasmon resonances, in the visible range, of each nanoprism array. Due to the strong electromagnetic field confinement effects at the nanoprism tips, demonstrated by finite element method simulations, these nanosystems proved to have enhanced nonlinear optical properties. Moreover, a tunable changeover from reverse saturable absorption (RSA) to saturable absorption (SA) can be obtained by properly controlling the bimetallic composition of the nanoprisms, without modifying the overall morphology of the nanosystems. This capability makes these nanosystems extremely interesting for the realization of solid-state nanophotonic devices with enhanced ultrafast nonlinear optical properties.
authors.affiliation: Physics and Astronomy Department and CNISM, University of Padova, via Marzolo 8, I-35131 Padova, Italy. tiziana.cesca@unipd.it.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Cesca
authors.forename: Niccolò
authors.initials: N
authors.lastname: Michieli
authors.forename: Boris
authors.initials: B
authors.lastname: Kalinic
authors.forename: Ana
authors.initials: A
authors.lastname: Sánchez-Espinoza
authors.forename: Marco
authors.initials: M
authors.lastname: Rattin
authors.forename: Valentina
authors.initials: V
authors.lastname: Russo
authors.forename: Valentina
authors.initials: V
authors.lastname: Mattarello
authors.forename: Carlo
authors.initials: C
authors.lastname: Scian
authors.forename: Paolo
authors.initials: P
authors.lastname: Mazzoldi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mattei