Media 2: Control of Fano asymmetry in plasmon induced transparency and its application to plasmonic waveguide modulator

Originally published in Optics Express on 13 August 2012 (oe-20-17-18994

Media 1: Control of Fano asymmetry in plasmon induced transparency and its application to plasmonic waveguide modulator

Originally published in Optics Express on 13 August 2012 (oe-20-17-18994

Disordered Potential Landscapes for Anomalous Delocalization and Superdiffusion of Light

The prominent distinction between order and disorder in optics has been understood in terms of the spatial spreading of waves. In the Anderson picture of optical disorder, light localization has been elucidated by the interference of multiple scatterings from disorders, thus implying a natural correspondence between the localization and disordered potentials. Here, we focus on the disorder of a wave itself to achieve a new class of disordered optical potentials with continuous landscapes, distinguished from conventional Anderson disorder or abnormal disorders in discrete systems. Starting from the disordered but extended ground state for the Schrödinger-like wave equation, we inversely develop the landscape of an optical potential, the disorder pattern of which is similar to Brownian random-walk motion. We then demonstrate that the modes in such a structure can extend over an anomalously large region of space, and also exhibit superdiffusive wave transport. Such behaviors are in contrast to the wavelength-scale localization commonly referred to as Anderson localization in conventional disordered potentials. Our results enable wave delocalization and signal transport in generalized disordered potentials with anomalous modal properties, without the aid of interactions between on-site and hopping energies

Visualization 1: Low-dimensional optical chirality in complex potentials

Spin black hole behavior at the EP. Originally published in Optica on 20 September 2016 (optica-3-9-1025

Supplement 1: Low-dimensional optical chirality in complex potentials

Supplementary material for “Low-dimensional optical chirality in complex potentials” Originally published in Optica on 20 September 2016 (optica-3-9-1025

Visualization 2: Low-dimensional optical chirality in complex potentials

Linear polarization (LP) incidence. Originally published in Optica on 20 September 2016 (optica-3-9-1025

Suppression of Radiative Damping and Enhancement of Second Harmonic Generation in Bull’s Eye Nanoresonators

We report a drastic increase of the damping time of plasmonic eigenmodes in resonant bull’s eye (BE) nanoresonators to more than 35 fs. This is achieved by tailoring the groove depth of the resonator and by coupling the confined plasmonic field in the aperture to an extended resonator mode such that spatial coherence is preserved over distances of more than 10 μm. Experimentally, this is demonstrated by probing the plasmon dynamics at the field level using broadband spectral interferometry. The nanoresonator allows us to efficiently concentrate the incident field inside the central aperture of the BE and to tailor its local optical nonlinearity by varying the aperture geometry. By replacing the central circular hole with an annular ring structure, we obtain 50-times higher second harmonic generation efficiency, allowing us to demonstrate the efficient concentration of long-lived plasmonic modes inside nanoapertures by interferometric frequency-resolved autocorrelation. Such a light concentration in a nanoresonator with high quality factor has high potential for sensing and coherent control of light-matter interactions on the nanoscale

Toward Plasmonics with Nanometer Precision: Nonlinear Optics of Helium-Ion Milled Gold Nanoantennas

Plasmonic nanoantennas are versatile tools for coherently controlling and directing light on the nanoscale. For these antennas, current fabrication techniques such as electron beam lithography (EBL) or focused ion beam (FIB) milling with Ga⁺-ions routinely achieve feature sizes in the 10 nm range. However, they suffer increasingly from inherent limitations when a precision of single nanometers down to atomic length scales is required, where exciting quantum mechanical effects are expected to affect the nanoantenna optics. Here, we demonstrate that a combined approach of Ga⁺-FIB and milling-based He⁺-ion lithography (HIL) for the fabrication of nanoantennas offers to readily overcome some of these limitations. Gold bowtie antennas with 6 nm gap size were fabricated with single-nanometer accuracy and high reproducibility. Using third harmonic (TH) spectroscopy, we find a substantial enhancement of the nonlinear emission intensity of single HIL-antennas compared to those produced by state-of-the-art gallium-based milling. Moreover, HIL-antennas show a vastly improved polarization contrast. This superior nonlinear performance of HIL-derived plasmonic structures is an excellent testimonial to the application of He⁺-ion beam milling for ultrahigh precision nanofabrication, which in turn can be viewed as a stepping stone to mastering quantum optical investigations in the near-field