19 research outputs found
Tapered Photonic Switching
The advent of novel nonlinear materials has stirred unprecedented interest in
exploring the use of temporal inhomogeneities to achieve novel forms of wave
control, amidst the greater vision of engineering metamaterials across both
space and time. When the properties of an unbounded medium are abruptly
switched in time, propagating waves are efficiently converted to different
frequencies, and partially coupled to their back-propagating phase-conjugate
partners, through a process called time-reversal. However, in realistic
materials the switching time is necessarily finite, playing a central role in
the resulting temporal scattering features. By identifying and leveraging the
crucial role of electromagnetic momentum conservation in time-reversal
processes, here we develop a very general analytical formalism to quantify
time-reversal due to temporal inhomogeneities of arbitrary profile. Finally, we
deploy our analytic theory to develop a formalism, analogous to spatial
tapering theory, that enables the tailoring of a desired time-reversal spectral
response, demonstrating its use for the realization of broadband frequency
converters and filters
An Archimedes' Screw for Light
An Archimedes' Screw captures water, feeding energy into it by lifting it to
a higher level. We introduce the first instance of an optical Archimedes'
Screw, and demonstrate how this system is capable of capturing light, dragging
it and amplifying it. We unveil new exact analytic solutions to Maxwell's
Equations for a wide family of chiral space-time media, and show their
potential to achieve chirally selective amplification within widely tunable
parity-time-broken phases. Our work, which may be readily implemented via
pump-probe experiments with circularly polarized beams, opens a new direction
in the physics of time-varying media by merging the rising field of space-time
metamaterials and that of chiral systems, and may form a new playground for
topology and non-Hermitian physics, with potential applications to chiral
spectroscopy and sensing
Twist-Induced Hyperbolic Shear Metasurfaces
Following the discovery of moir\'e-driven superconductivity in twisted
graphene multilayers, twistronics has spurred a surge of interest in tailored
broken symmetries through angular rotations, enabling new properties from
electronics to photonics and phononics. Analogously, in monoclinic polar
crystals a nontrivial angle between non-degenerate dipolar phonon resonances
can naturally emerge due to asymmetries in their crystal lattice, and its
variations are associated with intriguing polaritonic phenomena, including
axial dispersion, i.e., a rotation of the optical axis with frequency, and
microscopic shear effects that result in asymmetric loss distributions. So far
these phenomena were restricted to specific mid-infrared frequencies, difficult
to access with conventional lasers, and fundamentally limited by the degree of
asymmetry and the strength of light-matter interactions available in natural
crystals. Here, we leverage twistronics to demonstrate giant axial dispersion
and loss asymmetry of hyperbolic waves in elastic metasurfaces, by tailoring
the angle between coupled pairs of anisotropic metasurfaces. We show extreme
control over elastic wave dispersion via the twist angle, and leverage the
resulting phenomena to demonstrate reflection-free negative refraction, as well
as the application of axial dispersion to achieve diffraction-free
non-destructive testing, whereby the angular direction of a hyperbolic probe
wave is encoded into its frequency. Our work welds the concepts of twistronics,
non-Hermiticity and extreme anisotropy, demonstrating the powerful
opportunities enabled by metasurfaces for tunable, highly directional surface
acoustic wave propagation, of great interest for applications ranging from
seismic mitigation to on-chip phononics and wireless communications, paving the
way towards their translation into emerging photonic and polaritonic
metasurface technologies
Observation of Temporal Reflections and Broadband Frequency Translations at Photonic Time-Interfaces
Time-reflection is a uniform inversion of the temporal evolution of a signal,
which arises when an abrupt change in the properties of the host material
occurs uniformly in space. At such a time-interface, a portion of the input
signal is time-reversed, and its frequency spectrum is homogeneously translated
while its momentum is conserved, forming the temporal counterpart of a spatial
interface. Combinations of time-interfaces, forming time-metamaterials and
Floquet matter, exploit the interference of multiple time-reflections for
extreme wave manipulation, leveraging time as a new degree of freedom. Here, we
report the observation of photonic time-reflection and associated broadband
frequency translation in a switched transmission-line metamaterial whose
effective capacitance is homogeneously and abruptly changed via a synchronized
array of switches. A pair of temporal interfaces are combined to demonstrate
time-reflection-induced wave interference, realizing the temporal counterpart
of a Fabry-Perot cavity. Our results establish the foundational building blocks
to realize time-metamaterials and Floquet photonic crystals, with opportunities
for extreme photon manipulation in space and time
An Archimedes\u27 screw for light
An Archimedes’ Screw captures water, feeding energy into it by lifting it to a higher level. We introduce the first instance of an optical Archimedes’ Screw, and demonstrate how this system is capable of capturing light, dragging it and amplifying it. We unveil new exact analytic solutions to Maxwell’s Equations for a wide family of chiral space-time media, and show their potential to achieve chirally selective amplification within widely tunable parity-time-broken phases. Our work, which may be readily implemented via pump-probe experiments with circularly polarized beams, opens a new direction in the physics of time-varying media by merging the rising field of space-time metamaterials and that of chiral systems, and offers a new playground for topological and non-Hermitian photonics, with potential applications to chiral spectroscopy and sensing
New horizons in near-zero refractive index photonics and hyperbolic metamaterials
The engineering of the spatial and temporal properties of both the electric
permittivity and the refractive index of materials is at the core of photonics.
When vanishing to zero, those two variables provide new knobs to control
light-matter interactions. This perspective aims at providing an overview of
the state of the art and the challenges in emerging research areas where the
use of near-zero refractive index and hyperbolic metamaterials is pivotal, in
particular light and thermal emission, nonlinear optics, sensing applications
and time-varying photonics
Roadmap on multimode light shaping
Our ability to generate new distributions of light has been remarkably enhanced in recent years. At the most fundamental level, these light patterns are obtained by ingeniously combining different electromagnetic modes. Interestingly, the modal superposition occurs in the spatial, temporal as well as spatio-temporal domain. This generalized concept of structured light is being applied across the entire spectrum of optics: generating classical and quantum states of light, harnessing linear and nonlinear light-matter interactions, and advancing applications in microscopy, spectroscopy, holography, communication, and synchronization. This Roadmap highlights the common roots of these different techniques and thus establishes links between research areas that complement each other seamlessly. We provide an overview of all these areas, their backgrounds, current research, and future developments. We highlight the power of multimodal light manipulation and want to inspire new eclectic approaches in this vibrant research community.acceptedVersionPeer reviewe