Orad Reshef

Orad Reshef
University of Ottawa · Department of Physics

PhD Applied Physics

About

115
Publications
17,815
Reads
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1,523
Citations
Introduction
Dr. Orad Reshef is a Banting postdoctoral fellow at the University of Ottawa. He does research in nanophotonics, metamaterials and nonlinear optics. His current projects involve nonlinear epsilon-near-zero materials and integrated zero-index metamaterials.
Additional affiliations
August 2010 - July 2016
Harvard University
Position
  • PhD Student

Publications

Publications (115)
Article
The utility of all parametric nonlinear optical processes is hampered by phase-matching requirements. Quasi-phase-matching, birefringent phase matching, and higher-order-mode phase matching have all been developed to address this constraint, but the methods demonstrated to date suffer from the inconvenience of only being phase matched for a single,...
Article
Multiresonant metasurfaces could enable many applications in filtering, sensing, and nonlinear optics. However, developing a metasurface with more than one high-quality-factor or high-Q resonance at designated resonant wavelengths is challenging. Here, we experimentally demonstrate a plasmonic metasurface exhibiting different, narrow surface lattic...
Article
Full-text available
Conferences disseminate research, grow professional networks and train employees. Unfortunately, they also contribute to climate change and present barriers to achieving a socially sustainable work environment. Here, we analyse the recent impact of transforming in-person conferences into virtual conferences on improving diversity, equity and inclus...
Article
Asymmetric transmission - direction-selective electromagnetic transmission between two ports - is a phenomenon exhibited by two-dimensional chiral systems. The possibility of exploiting this phenomenon in chiral metasurfaces opens exciting possibilities for applications such as optical isolation and routing without external magnetic fields. This wo...
Article
The development of metasurfaces has enabled unprecedented portability and functionality in flat optical devices. Spaceplates have recently been introduced as a complementary element to reduce the space between individual metalenses, which will further miniaturize entire imaging devices. However, spaceplates necessitate an optical response which dep...
Preprint
Resonances in optical systems are useful for many applications, such as frequency comb generation, optical filtering, and biosensing. However, many of these applications are difficult to implement in optical metasurfaces because traditional approaches for designing multi-resonant nanostructures require significant computational and fabrication effo...
Preprint
Multiresonant metasurfaces could enable many applications in filtering, sensing and nonlinear optics. However, developing a metasurface with more than one high-quality-factor or high-Q resonance at designated resonant wavelengths is challenging. Here, we experimentally demonstrate a plasmonic metasurface exhibiting different, narrow surface lattice...
Article
There isn’t one single ‘early career experience’ in physics, and different subfields involve very different opportunities and challenges. Seven early career physicists who work on a range of research topics in different subfields discuss their views on the lessons we can learn from their professional lives.
Preprint
Full-text available
Asymmetric transmission - direction-selective control of electromagnetic transmission between two ports - is an important phenomenon typically exhibited by two-dimensional chiral systems. Here, we study this phenomenon in chiral plasmonic metasurfaces supporting lattice plasmons modes. We show, both numerically and experimentally, that asymmetric t...
Preprint
The development of metasurfaces has enabled unprecedented portability and functionality in flat optical devices. Spaceplates have recently been introduced as a complementary element to reduce the space between individual metalenses. This will further miniaturize entire imaging devices. However, a spaceplate necessitates a non-local optical response...
Article
Full-text available
We experimentally investigate the tunable Doppler shift in an 80 nm thick indium-tin-oxide (ITO) film at its epsilon-near-zero (ENZ) region. Under strong and pulsed excitation, ITO exhibits a time-varying change in the refractive index. A maximum frequency redshift of 1.8 THz is observed in the reflected light when the pump light has a peak intensi...
Article
Full-text available
Centuries of effort to improve imaging has focused on perfecting and combining lenses to obtain better optical performance and new functionalities. The arrival of nanotechnology has brought to this effort engineered surfaces called metalenses, which promise to make imaging devices more compact. However, unaddressed by this promise is the space betw...
Preprint
Full-text available
The nonlinear optical response of materials is the foundation upon which applications such as frequency conversion, all-optical signal processing, molecular spectroscopy, and nonlinear microscopy are built. However, the utility of all such parametric nonlinear optical processes is hampered by phase-matching requirements. Quasi-phase-matching, biref...
Article
Full-text available
Plasmonic nanostructures hold promise for the realization of ultra-thin sub-wavelength devices, reducing power operating thresholds and enabling nonlinear optical functionality in metasurfaces. However, this promise is substantially undercut by absorption introduced by resistive losses, causing the metasurface community to turn away from plasmonics...
Conference Paper
We present an epsilon-near-zero metamaterial consisting of a subwavelength periodic stack of metal and dielectric layers with enhanced nonlinear optical response in its zero-permittivity wavelength. This ENZ condition can be tuned by adjusting layer thickness.
Preprint
Full-text available
Among many roles, conferences disseminate research, grow professional networks, and train employees. They also significantly contribute to climate change due to their sizable carbon footprint. More recently, additional negative aspects have surfaced. Namely, they present significant barriers to achieving Diversity, Equity, and Inclusion (DEI). Here...
Article
Spontaneous emission, stimulated emission and absorption are the three fundamental radiative processes describing light-matter interactions. Here, we theoretically study the behaviour of these fundamental processes inside an unbounded medium exhibiting a vanishingly small refractive index, i.e., a near-zero-index (NZI) host medium. We present a gen...
Article
Full-text available
We demonstrate ultrafast tuning of a plasmonic spectral filter at terahertz (THz) frequencies. The device is made of periodically spaced gold crosses deposited on the surface of an undoped silicon wafer in which transient free carriers can be optically injected with a femtosecond resonant pulse. We demonstrate the concept by measuring the transmiss...
Article
Full-text available
Rapid advances in high‐resolution chip lithography have accelerated nanophotonic device development on the silicon‐on‐insulator (SOI) platform. The ability to create sub‐wavelength features in silicon has attracted research in photonic band and dispersion engineering and consequently made available a wide array of device functionalities. By drawing...
Preprint
Full-text available
We demonstrate that a periodic stack of alternating, subwavelength Ag and SiO$_2$ layers can be designed to place its zero-permittivity wavelength anywhere in the visible. We find that such a metamaterial displays strong nonlinear response in its near-zero-permittivity region, with a Kerr coefficient and nonlinear absorption coefficient as large as...
Article
Full-text available
Space-time duality in paraxial optical wave propagation implies the existence of intriguing effects when light interacts with a material exhibiting two refractive indexes separated by a boundary in time. The direct consequence of such time-refraction effect is a change in the frequency of light while leaving the wavevector unchanged. Here, we exper...
Preprint
Full-text available
Resonant cavities play a crucial role in many aspects of science and engineering. A resonator with a large quality-factor (Q-factor) is essential to many applications in photonics, such as filtering, delay lines and memories, lasing, switching, spectroscopy, sensing, and nonlinear optical processes, among others. Recently, the rapid development of...
Preprint
Full-text available
Spontaneous emission, stimulated emission and absorption are the three fundamental radiative processes describing light-matter interactions. Here, we theoretically study the behaviour of these fundamental processes inside an unbounded medium exhibiting a vanishingly small refractive index, i.e., a near-zero-index (NZI) host medium. We present a gen...
Article
Full-text available
The first online-only meeting in photonics, held on 13 January 2020, was a resounding success, with 1100 researchers participating remotely to discuss the latest advances in photonics. Here, the organizers share their tips and advice on how to organize an online conference. The first online-only meeting in photonics, held on January 13th 2020, was...
Preprint
Full-text available
On January 13th 2020, the inaugural Photonics Online Meetup (POM) brought together more than 1100 researchers to discuss the latest advances in photonics. Or rather, it didn't, because the meeting was completely delocalized with the speakers, organizers, and attendees scattered across six continents and hundreds of locations, connected via a video-...
Preprint
Full-text available
Centuries of effort to improve imaging has focused on perfecting and combining lenses to obtain better optical performance, such as achromatic lenses, and new functionalities, such as microscopy. The arrival of nanotechnology has now enabled thin subwavelength-structured surfaces called metalenses, which promise to make imaging devices more compact...
Article
Full-text available
Nonlinear optical phenomena are paramount in many photonic applications ranging from frequency broadening and generation of ultrashort pulses to frequency comb-based metrology. A recent trend has been to miniaturize photonic components, resulting also in a demand for small scale nonlinear components. This demand is difficult to address by using con...
Conference Paper
We theoretically introduce a new optic, a plate that reduces propagation length for image formation. We experimentally demonstrate it advances a beam’s focus and shifts an obliquely incident beam identically to a longer propagation distance.
Conference Paper
We experimentally demonstrate adiabatic wavelength conversion using a time-varying epsilon-near-zero-based metasurface. We observe up to 47-mn redshift with 4-GW/cnr pump peak intensity. The wavelength shift depends on both pump-probe delay time and pmnp peak intensity.
Conference Paper
Full-text available
We experimentally demonstrate an unprecedented ultra-high-Q («2400) surface lattice resonance in a metasurface array of periodically arranged plasmonic nanostructures, which can be adopted for highly efficient nanophotonic applications e.g. nano-lasing, sensing, and nonlinear optical processes.
Conference Paper
We experimentally demonstrate omni-directional phase matching via four-wave mixing in zero-index silicon waveguides exhibiting phase-free propagation in the infrared range. This property can be exploited to miniaturize integrated nonlinear devices.
Conference Paper
We theoretically introduce a new optic, a plate that reduces propagation length for image formation. We experimentally demonstrate it advances a beam’s focus and shifts an obliquely incident beam identically to a longer propagation distance.
Conference Paper
Full-text available
We investigate active tunability of plasmonic filters on silicon with FDTD. Injecting free-charge carriers changes the dielectric properties of the substrate and bleaches the plasmonic resonance while inducing a blueshift and linewidth broadening.
Article
Full-text available
An invisibility cloak should completely hide an object from an observer, ideally across the visible spectrum and for all angles of incidence and polarizations of light, in three dimensions. However, until now, all such devices have been limited to either small bandwidths or have disregarded the phase of the impinging wave or worked only along speci...
Article
Resonant metasurfaces are devices composed of nanostructured sub-wavelength scatterers that generate narrow optical resonances, enabling applications in filtering, nonlinear optics, and molecular fingerprinting. It is highly desirable for these applications to incorporate such devices with multiple, high-quality-factor resonances; however, it can b...
Article
We numerically investigate second-harmonic generation from multiresonant plasmonic metasurfaces by designing an array consisting of L-shaped aluminum nanoparticles that simultaneously supports two surface lattice resonances with relatively high quality factors (>100). Using an approach based on the nonlinear discrete-dipole approximation, we predic...
Preprint
Full-text available
Resonant metasurfaces are devices composed of nanostructured sub-wavelength scatterers that generate narrow optical resonances, enabling applications in filtering, nonlinear optics, and molecular fingerprinting. It is highly desirable for these applications to incorporate such devices with multiple, high-quality-factor resonances; however, it can b...
Article
Materials with vanishingly small dielectric permittivity, known as epsilon-near-zero materials, enable strong ultrafast optical nonlinear responses within a sub-wavelength propagation length. This Review surveys the various observations of nonlinear phenomena in this class of materials.