title: Coherent selection of invisible high-order electromagnetic excitations.
abstract: Far-field spectroscopy and mapping of electromagnetic near-field distribution are the two dominant tools for analysis and characterization of the electromagnetic response in nanophotonics. Despite the widespread use, these methods can fail at identifying weak electromagnetic excitations masked by stronger neighboring excitations. This is particularly problematic in ultrafast nanophotonics, including optical sensing, nonlinear optics and nanolasers, where the broad resonant modes can overlap to a significant degree. Here, using plasmonic metamaterials, we demonstrate that coherent spectroscopy can conveniently isolate and detect such hidden high-order photonic excitations. Our results establish that the coherent spectroscopy is a powerful new tool. It complements the conventional methods for analysis of the electromagnetic response, and provides a new route to designing and characterizing novel photonic devices and materials.
authors.affiliation: Department of Physics, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Ming Lun
authors.initials: ML
authors.lastname: Tseng
authors.affiliation: Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: Xu
authors.initials: X
authors.lastname: Fang
authors.affiliation: Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: Vassili
authors.initials: V
authors.lastname: Savinov
authors.affiliation: Department of Physics, National Taiwan University, Taipei 10617, Taiwan.|Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Pin Chieh
authors.initials: PC
authors.lastname: Wu
authors.affiliation: Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Southampton SO17 1BJ, UK.
authors.forename: Jun-Yu
authors.initials: JY
authors.lastname: Ou
authors.affiliation: Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Southampton SO17 1BJ, UK.|Centre for Disruptive Photonic Technologies, TPI, SPMS, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Nikolay I
authors.initials: NI
authors.lastname: Zheludev
authors.affiliation: Department of Physics, National Taiwan University, Taipei 10617, Taiwan.|Research Center for Applied Sciences, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Din Ping
authors.initials: DP
authors.lastname: Tsai