Photonic metasurfaces for spatiotemporal and ultrafast light control
Abstract
The emergence of photonic metasurfaces - planar arrays of nano-antennas - has enabled a new paradigm of light control through wave-front engineering. Space-gradient metasurfaces induce spatially varying phase and/or polarization to propagating light. As a consequence, photons propagating through space-gradient metasurfaces can be engineered to undergo a change to their momentum, angular momentum and/or spin states. In our study, we implement metasurface-based devices that break the spin symmetry of light to obtain Photonic Spin Hall Effect (PSHE). We utilized PSHE to design a real-time circular dichroism spectrometer, a device vital in bio-sensing, and an optical rotator used in secure quantum communications. In addition, we developed metasurface based Fabry–Pérot nano-cavities, which go beyond the diffraction limit of light, a requirement to enhance photonic spontaneous emission using the Purcell effect. In addition, we demonstrate that the field of flat photonics is further empowered by utilizing time-gradient metasurfaces with dynamic responses to propagating light. A new genus of optical devices and physical effects can be realized. Photons experience inelastic interactions with time-varying metasurfaces resulting in a Doppler-like wavelength-shift. Furthermore, Snell’s relations are modified to a more universal form not limited by Lorentz reciprocity, hence meeting all the requirements to build magnetic-free optical isolators. Finally, we construct the concept of ultrafast metasurfaces. We integrate spatial interference methodology delivered by metasurfaces and temporal interference of phase-locked frequency-comb provided by ultrafast technology. This leads to generation of coherent 4D space-time optical patterns, which is implemented to achieve ultrafast laser beam steering over hundred-picosecond scale.
Degree
Ph.D.
Advisors
Shalaev, Purdue University.
Subject Area
Optics|Materials science
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