Hurricanes, tsunami, rogue waves and tornadoes are rare natural phenomena that embed an exceptionally large amount of energy, which appears and quickly disappears in a probabilistic fashion. This makes them difficult to predict and hard to generate on demand. Here we demonstrate that we can trigger the onset of rare events akin to rogue waves controllably, while we can systematically use their generation to break the diffraction limit of light propagation. We illustrate this phenomenon in the interesting case of a random field, where energy oscillates among incoherent degrees of freedom. Despite the low energy carried by each wave, we illustrate how to control a mechanism of spontaneous synchronization, which constructively builds up the spectral energy available in the whole bandwidth of the field into giant coherent structures, whose statistics is perfectly predictable. The larger the frequency bandwidth of the random field, the larger the amplitude of rare events that are built up by this mechanism. Our system is composed of an integrated optical resonator, realized on a photonic crystal chip. Trough near field imaging experiments, we record the most confined rogue waves ever reported, characterized by a spatial localization of 206 µm and with ultrashort duration of 163 fs at the wavelength λ = 1.55 µm. Quite remarkably, such localized energy patterns are formed in a deterministic dielectric structure that does not require nonlinear properties. * andrea.fratalocchi@kaust.edu.sa; www.primalight.org
Near-field imaging is a powerful tool to investigate the complex structure of light at the nanoscale. Recent advances in near-field imaging have indicated the possibility for the complete reconstruction of both electric and magnetic components of the evanescent field. Here we study the electro-magnetic field structure of surface plasmon polariton waves propagating along subwavelength gold nanowires by performing phase- and polarization-resolved near-field microscopy in collection mode. By applying the optical reciprocity theorem, we describe the signal collected by the probe as an overlap integral of the nanowire’s evanescent field and the probe’s response function. As a result, we find that the probe’s sensitivity to the magnetic field is approximately equal to its sensitivity to the electric field. Through rigorous modeling of the nanowire mode as well as the aperture probe response function, we obtain a good agreement between experimentally measured signals and a numerical model. Our findings provide a better understanding of aperture-based near-field imaging of the nanoscopic plasmonic and photonic structures and are helpful for the interpretation of future near-field experiments.
Optimum design of efficient nanowire solar cells requires better
understanding of light diffusion in a nanowire array. Here we demonstrate that
our recently developed ultrafast all-optical shutter can be used to directly
measure the dwell time of light in a nanowire array. Our measurements on
disordered ZnO nanowire arrays, "nanowire forests," indicate that the photon
mean free path and the dwell time of light can be well predicted from SEM
images
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