Master of Science, Ain Shams University (2009)
Doctor of Philosophy, Purdue University (2015)
Mark Brongersma, Postdoctoral Faculty Sponsor
- Adiabatic frequency shifting in epsilon-near-zero materials: the role of group velocity OPTICA 2020; 7 (3): 226–31
Spatiotemporal light control with frequency-gradient metasurfaces.
Science (New York, N.Y.)
2019; 365 (6451): 374–77
The capability of on-chip wavefront modulation has the potential to revolutionize many optical device technologies. However, the realization of power-efficient phase-gradient metasurfaces that offer full-phase modulation (0 to 2π) and high operation speeds remains elusive. We present an approach to continuously steer light that is based on creating a virtual frequency-gradient metasurface by combining a passive metasurface with an advanced frequency-comb source. Spatiotemporal redirection of light naturally occurs as optical phase-fronts reorient at a speed controlled by the frequency gradient across the virtual metasurface. An experimental realization of laser beam steering with a continuously changing steering angle is demonstrated with a single metasurface over an angle of 25° in just 8 picoseconds. This work can support integrated-on-chip solutions for spatiotemporal optical control, directly affecting emerging applications such as solid-state light detection and ranging (LIDAR), three-dimensional imaging, and augmented or virtual systems.
View details for DOI 10.1126/science.aax2357
View details for PubMedID 31346064
Spatiotemporal light control with active metasurfaces.
Science (New York, N.Y.)
2019; 364 (6441)
Optical metasurfaces have provided us with extraordinary ways to control light by spatially structuring materials. The space-time duality in Maxwell's equations suggests that additional structuring of metasurfaces in the time domain can even further expand their impact on the field of optics. Advances toward this goal critically rely on the development of new materials and nanostructures that exhibit very large and fast changes in their optical properties in response to external stimuli. New physics is also emerging as ultrafast tuning of metasurfaces is becoming possible, including wavelength shifts that emulate the Doppler effect, Lorentz nonreciprocity, time-reversed optical behavior, and negative refraction. The large-scale manufacturing of dynamic flat optics has the potential to revolutionize many emerging technologies that require active wavefront shaping with lightweight, compact, and power-efficient components.
View details for DOI 10.1126/science.aat3100
View details for PubMedID 31097638
- Photonic Spin Hall Effect in Robust Phase Gradient Metasurfaces Utilizing Transition Metal Nitrides ACS PHOTONICS 2019; 6 (1): 99–106
Ultrathin and multicolour optical cavities with embedded metasurfaces
2018; 9: 2673
Over the past years, photonic metasurfaces have demonstrated their remarkable and diverse capabilities in advanced control over light propagation. Here, we demonstrate that these artificial films of deeply subwavelength thickness also offer new unparalleled capabilities in decreasing the overall dimensions of integrated optical systems. We propose an original approach of embedding a metasurface inside an optical cavity-one of the most fundamental optical elements-to drastically scale-down its thickness. By modifying the Fabry-Pérot interferometric principle, this methodology is shown to reduce the metasurface-based nanocavity thickness below the conventional λ/(2n) minimum. In addition, the nanocavities with embedded metasurfaces can support independently tunable resonances at multiple bands. As a proof-of-concept, using nanostructured metasurfaces within 100-nm nanocavities, we experimentally demonstrate high spatial resolution colour filtering and spectral imaging. The proposed approach can be extrapolated to compact integrated optical systems on-a-chip such as VCSEL's, high-resolution spatial light modulators, imaging spectroscopy systems, and bio-sensors.
View details for PubMedID 29991722