title: Nanowire antenna absorption probed with time-reversed fourier microscopy.
abstract: Understanding light absorption in individual nanostructures is crucial for optimizing the light-matter interaction at the nanoscale. Here, we introduce a technique named time-reversed Fourier microscopy that enables the measurement of the angle-dependent light absorption in dilute arrays of uncoupled semiconductor nanowires. Because of their large separation, the nanowires have a response that can be described in terms of individual nanostructures. The geometry of individual nanowires makes them behave as nanoantennas that show a strong interaction with the incident light. The angle-dependent absorption measurements, which are compared to numerical simulations and Mie scattering calculations, show the transition from guided-mode to Mie-resonance absorption in individual nanowires and the relative efficiency of these two absorption mechanisms in the same nanostructures. Mie theory fails to describe the absorption in finite-length vertical nanowires illuminated at small angles with respect to their axis. At these angles, the incident light is efficiently absorbed after being coupled to guided modes. Our findings are relevant for the design of nanowire-based photodetectors and solar cells with an optimum efficiency.
authors.affiliation: FOM Institute for Atomic and Molecular Physics (AMOLF) , c/o Philips Research, High-Tech Campus 4, 5656 AE Eindhoven, The Netherlands.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Grzela
authors.forename: Ramón
authors.initials: R
authors.lastname: Paniagua-Domínguez
authors.forename: Tommy
authors.initials: T
authors.lastname: Barten
authors.forename: Dick
authors.initials: D
authors.lastname: van Dam
authors.forename: José A
authors.initials: JA
authors.lastname: Sánchez-Gil
authors.forename: Jaime Gómez
authors.initials: JG
authors.lastname: Rivas