Dynamic control and manipulation of near-fields using direct feedback.

Shaping and controlling electromagnetic fields at the nanoscale is vital for advancing efficient and compact devices used in optical communications, sensing and metrology, as well as for the exploration of fundamental properties of light-matter interaction and optical nonlinearity. Real-time feedback for active control over light can provide a significant advantage in these endeavors, compensating for ever-changing experimental conditions and inherent or accumulated device flaws. Scanning nearfield microscopy, being slow in essence, cannot provide such a real-time feedback that was thus far possible only by scattering-based microscopy.

Spin-Orbit Interaction of Light in Plasmonic Lattices.

In the past decade, the spin-orbit interaction (SOI) of light has been a driving force in the design of metamaterials, metasurfaces, and schemes for light-matter interaction. A hallmark of the spin-orbit interaction of light is the spin-based plasmonic effect, converting spin angular momentum of propagating light to near-field orbital angular momentum. Although this effect has been thoroughly investigated in circular symmetry, it has yet to be characterized in a noncircular geometry, where whirling, periodic plasmonic fields are expected.

Double moiré structured illumination microscopy with high-index materials.

Structured illumination microscopy utilizes illumination of periodic light patterns to allow reconstruction of high spatial frequencies, conventionally doubling the microscope's resolving power. This Letter presents a structured illumination microscopy scheme with the ability to achieve 60 nm resolution by using total internal reflection of a double moiré pattern in high-index materials. We propose a realization that provides dynamic control over relative amplitudes and phases of four coherently interfering beams in gallium phosphide and numerically demonstrate its capability.

Linearly dichroic plasmonic lens and hetero-chiral structures.

We present an experimental study of Hetero-Chiral (HC) plasmonic lenses, comprised of constituents with opposite chirality, demonstrating linearly dichroic focusing. The lenses focus only light with a specific linear polarization and result in a dark focal spot for the orthogonal polarization state. We introduce the design concepts and quantitatively compare several members of the HC family, deriving necessary conditions for linear dichroism and several comparative engineering parameters.

Metafocusing by a Metaspiral Plasmonic Lens.

We designed and realized a metasurface (manipulating the local geometry) spiral (manipulating the global geometry) plasmonic lens, which fundamentally overcomes the multiple efficiency and functionality challenges of conventional in-plane plasmonic lenses. The combination of spirality and metasurface achieves much more efficient and uniform linear-polarization-independent plasmonic focusing. As for functionality, under matched circularly polarized illumination the lens directs all of the power coupled to surface plasmon polaritons (SPPs) into the focal spot, while the orthogonal polarization excites only diverging SPPs that do not penetrate the interior of the lens, achieving 2 orders of magnitude intensity contrast throughout the entire area of the lens.

Spatiotemporal focusing in opaque scattering media by wave front shaping with nonlinear feedback.

We experimentally demonstrate spatiotemporal focusing of light on single nanocrystals embedded inside a strongly scattering medium. Our approach is based on spatial wave front shaping of short pulses, using second harmonic generation inside the target nanocrystals as the feedback signal. We successfully develop a model both for the achieved pulse duration as well as the observed enhancement of the feedback signal.

Index mismatch aberration correction over long working distances using spatial light modulation.

For many microscopy applications, millimeters-long free working distances (LWD) are required. However, the high resolution and contrast of LWD objectives operated in air are lost when introducing glass and/or liquid with the sample. We propose to use spatial light modulation to correct for such beam aberrations caused by refractive index mismatches.

Control of light transmission through opaque scattering media in space and time.

We report the first experimental demonstration of combined spatial and temporal control of light transmission through opaque media. This control is achieved by solely manipulating spatial degrees of freedom of the incident wave front. As an application, we demonstrate that the present approach is capable of forming bandwidth-limited ultrashort pulses from the otherwise randomly transmitted light with a controllable interaction time of the pulses with the medium.