Doctor of Philosophy, University Of Birmingham (2015)
Master of Science, University Of Birmingham (2011)
Jennifer Dionne, Postdoctoral Faculty Sponsor
- Active polarization control with a parity-time-symmetric plasmonic resonator PHYSICAL REVIEW B 2018; 98 (16)
- Roadmap on plasmonics JOURNAL OF OPTICS 2018; 20 (4)
Nonreciprocal Flat Optics with Silicon Metasurfaces
2018; 18 (2): 1104–9
Metasurfaces enable almost complete control of light through ultrathin, subwavelength surfaces by locally and abruptly altering the scattered phase. To date, however, all metasurfaces obey time-reversal symmetry, meaning that forward and backward traveling waves will trace identical paths when being reflected, refracted, or diffracted. Here, we use full-field calculations to design a passive metasurface for nonreciprocal transmission of both direct and anomalously refracted near-infrared light over nanoscale optical path lengths. The metasurface consists of a 100 nm-thick, periodically patterned Si slab. Owing to the high-quality-factor resonances of the metasurface and the inherent Kerr nonlinearities of Si, this structure acts as an optical diode for free-space optical signals. This structure also exhibits nonreciprocal anomalous refraction with appropriate patterning to form a phase gradient metasurface. Compared to existing schemes for breaking time-reversal symmetry, our platform enables subwavelength nonreciprocity for arbitrary free-space optical inputs and provides a straightforward path to experimental realization. The concept is also generalizable to other metasurface functions, providing a foundation for one-way lensing and holography.
View details for PubMedID 29369641
Chemically Responsive Elastomers Exhibiting Unity-Order Refractive Index Modulation.
Advanced materials (Deerfield Beach, Fla.)
2018; 30 (7)
Chameleons are masters of light, expertly changing their color, pattern, and reflectivity in response to their environment. Engineered materials that share this tunability can be transformative, enabling active camouflage, tunable holograms, and novel colorimetric medical sensors. While progress has been made in creating artificial chameleon skin, existing schemes often require external power, are not continuously tunable, and may prove too stiff or bulky for applications. Here, a chemically tunable, large-area metamaterial is demonstrated that accesses a wide range of colors and refractive indices. An ordered monolayer of nanoresonators is fabricated, then its optical response is dynamically tuned by infiltrating its polymer substrate with solvents. The material shows a strong magnetic response with a dependence on resonator spacing that leads to a highly tunable effective permittivity, permeability, and refractive index spanning negative and positive values. The unity-order index tuning exceeds that of traditional electro-optic and photochromic materials and is robust to cycling, providing a path toward programmable optical elements and responsive light routing.
View details for PubMedID 29315902
- Broadband and wide-angle nonreciprocity with a non-Hermitian metamaterial PHYSICAL REVIEW B 2018; 97 (4)