Doctor of Philosophy, University Of Birmingham (2015)
Master of Science, University Of Birmingham (2011)
Jennifer Dionne, Postdoctoral Faculty Sponsor
- High Quality Factor Dielectric Metasurfaces for Ultraviolet Circular Dichroism Spectroscopy ACS PHOTONICS 2020; 7 (1): 36–42
Dynamic Focusing with High-Quality-Factor Metalenses.
Metasurface lenses provide an ultrathin platform in which to focus light, but weak light-matter interactions limit their dynamic tunability. Here we design submicron-thick, ultrahigh quality factor (high-Q) metalenses that enable dynamic modulation of the focal length and intensity. Using full-field simulations, we show that quality factors exceeding 5000 can be generated by including subtle, periodic perturbations within the constituent Si nanoantennas. Such high-Q resonances enable lens modulation based on the nonlinear Kerr effect, with focal lengths varying from 4 to 6.5 μm and focal intensities decreasing by half as input intensity increases from 0.1 to 1 mW/μm2. We also show how multiple high-Q resonances can be embedded in the lens response through judicious placement of the perturbations. Our high-Q lens design, with quality factors 2 orders of magnitude higher than existing lens designs, provides a foundation for reconfigurable, multiplexed, and hyperspectral metasurface imaging platforms.
View details for DOI 10.1021/acs.nanolett.0c01359
View details for PubMedID 32497434
Towards all-optical chiral resolution and few-molecule circular dichroism spectroscopy with dielectric metasurfaces
AMER CHEMICAL SOC. 2019
View details for Web of Science ID 000525061503599
All-dielectric, mid-infrared metasurfaces for vibrational circular dichroism enhancement
AMER CHEMICAL SOC. 2019
View details for Web of Science ID 000525055501500
Nanoscale nonreciprocity via photon-spin-polarized stimulated Raman scattering.
2019; 10 (1): 3297
Time reversal symmetry stands as a fundamental restriction on the vast majority of optical systems and devices. The reciprocal nature of Maxwell's equations in linear, time-invariant media adds complexity and scale to photonic diodes, isolators, circulators and also sets fundamental efficiency limits on optical energy conversion. Though many theoretical proposals and low frequency demonstrations of nonreciprocity exist, Faraday rotation remains the only known nonreciprocal mechanism that persists down to the atomic scale. Here, we present photon-spin-polarized stimulated Raman scattering as a new nonreciprocal optical phenomenon which has, in principle, no lower size limit. Exploiting this process, we numerically demonstrate nanoscale nonreciprocal transmission of free-space beams at near-infrared frequencies with a 250nm thick silicon metasurface as well as a fully-subwavelength plasmonic gap nanoantenna. In revealing all-optical spin-splitting, our results provide a foundation for compact nonreciprocal communication and computing technologies, from nanoscale optical isolators and full-duplex nanoantennas to topologically-protected networks.
View details for DOI 10.1038/s41467-019-11175-z
View details for PubMedID 31341164
- Enantiospecific Optical Enhancement of Chiral Sensing and Separation with Dielectric Metasurfaces ACS PHOTONICS 2019; 6 (1): 43–49
- 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)
Photonic Weyl degeneracies in magnetized plasma.
2016; 7: 12435
Weyl particles are elusive relativistic fermionic particles with vanishing mass. While not having been found as an elementary particle, they are found to emerge in solid-state materials where three-dimensional bands develop a topologically protected point-like crossing, a so-called Weyl point. Photonic Weyl points have been recently realised in three-dimensional photonic crystals with complex structures. Here we report the presence of a novel type of plasmonic Weyl points in a naturally existing medium-magnetized plasma, in which Weyl points arise as crossings between purely longitudinal plasma modes and transverse helical propagating modes. These photonic Weyl points are right at the critical transition between a Weyl point with the traditional closed finite equifrequency surfaces and the newly proposed 'type II' Weyl points with open equifrequency surfaces. Striking observable features of plasmon Weyl points include a half k-plane chirality manifested in electromagnetic reflection. Our study introduces Weyl physics into homogeneous photonic media, which could pave way for realizing new topological photonic devices.
View details for PubMedID 27506514
View details for PubMedCentralID PMC4987518