260 research outputs found
Thermal radiation from optically driven Kerr () photonic cavities
We study thermal radiation from nonlinear () photonic cavities
coupled to external channels and subject to incident monochromatic light. Our
work extends related work on nonlinear mechanical oscillators [Phys. Rev. Lett.
97, 110602 (2006)] to the problem of thermal radiation, demonstrating that
bistability can enhance thermal radiation by orders of magnitude and result in
strong lineshape alternations, including "super-narrow spectral peaks"
occurring at the onset of kinetic phase transitions. We show that when the
cavities are designed so as to have perfect linear absorptivity (rate
matching), such thermally activated transitions can be exploited to
dramatically tune the output power and radiative properties of the cavity,
leading to a kind of Kerr-mediated thermo-optic effect. Finally, we demonstrate
that in certain parameter regimes, the output radiation exhibits Stokes and
anti-Stokes side peaks whose relative magnitudes can be altered by tuning the
internal temperature of the cavity relative to its surroundings, a consequence
of strong correlations and interference between the emitted and reflected
radiation
Topology optimization of freeform large-area metasurfaces
We demonstrate optimization of optical metasurfaces over --
degrees of freedom in two and three dimensions, 100--1000+ wavelengths
() in diameter, with 100+ parameters per . In particular,
we show how topology optimization, with one degree of freedom per
high-resolution "pixel," can be extended to large areas with the help of a
locally periodic approximation that was previously only used for a few
parameters per . In this way, we can computationally discover
completely unexpected metasurface designs for challenging multi-frequency,
multi-angle problems, including designs for fully coupled multi-layer
structures with arbitrary per-layer patterns. Unlike typical metasurface
designs based on subwavelength unit cells, our approach can discover both sub-
and supra-wavelength patterns and can obtain both the near and far fields
Enhanced nonlinear frequency conversion and Purcell enhancement at exceptional points
We derive analytical formulas quantifying radiative emission from
subwavelength emitters embedded in triply resonant nonlinear
cavities supporting exceptional points (EP) made of dark and leaky modes. We
show that the up-converted radiation rate in such a system can be greatly
enhanced---by up to two orders of magnitude---compared to typical Purcell
factors achievable in non-degenerate cavities, for both monochromatic and
broadband emitters. We provide a proof-of-concept demonstration by studying an
inverse-designed 2D photonic-crystal slab that supports an EP formed out of a
Dirac cone at the emission frequency and a phase-matched, leaky-mode resonance
at the second harmonic frequency
Unidirectional Invisibility Induced by PT-Symmetric Periodic Structures
Parity-time (PT) symmetric periodic structures, near the spontaneous PT-symmetry breaking point, can act as unidirectional invisible media. In this regime, the reflection from one end is diminished while it is enhanced from the other. Furthermore, the transmission coefficient and phase are indistinguishable from those expected in the absence of a grating. The phenomenon is robust even in the presence of Kerr nonlinearities, and it can also effectively suppress optical bistabilities
Topology Optimized Multi-layered Meta-optics
We propose a general topology optimization framework for metasurface inverse
design that can automatically discover highly complex multi-layered
meta-structures with increased functionalities. In particular, we present
topology-optimized multi-layered geometries exhibiting angular phase control,
including a single-piece nanophotonic metalens with angular aberration
correction as well as an angle-convergent metalens that focuses light onto the
same focal spot regardless of the angle of incidence
Overlapping domains for topology optimization of large-area metasurfaces
We introduce an overlapping-domain approach to large-area metasurface design,
in which each simulated domain consists of a unit cell and overlapping regions
from the neighboring cells plus PML absorbers. We show that our approach
generates greatly improved metalens quality compared to designs produced using
a locally periodic approximation, thanks to better accuracy
with similar computational cost. We use the new approach with topology
optimization to design large-area () high-NA (0.71) multichrome and
broadband achromatic lenses with high focusing efficiency (),
greatly improving upon previously reported works
High-efficiency degenerate four wave-mixing in triply resonant nanobeam cavities
We demonstrate high-efficiency, degenerate four-wave mixing in triply
resonant Kerr photonic crystal (PhC) nanobeam cavities. Using a
combination of temporal coupled mode theory and nonlinear finite-difference
time-domain (FDTD) simulations, we study the nonlinear dynamics of resonant
four-wave mixing processes and demonstrate the possibility of observing
high-efficiency limit cycles and steady-state conversion corresponding to
% depletion of the pump light at low powers, even including
effects due to losses, self- and cross-phase modulation, and imperfect
frequency matching. Assuming operation in the telecom range, we predict close
to perfect quantum efficiencies at reasonably low 50 mW input powers in
silicon micrometer-scale cavities
Nonlinear Multi-Resonant Cavity Quantum Photonics Gyroscopes Quantum Light Navigation
We propose an on-chip all-optical gyroscope based on nonlinear multi-resonant
cavity quantum photonics in thin film resonators -- Quantum-Optic
Nonlinear Gyro or QONG in short. The key feature of our gyroscope is co-arisal
and co-accumulation of quantum correlations, nonlinear wave mixing and
non-inertial signals, all inside the same sensor-resonator. We theoretically
analyze the Fisher Information of our QONGs under fundamental quantum noise
conditions. Using Bayesian optimization, we maximize the Fisher Information and
show that improvement is possible over the shot-noise limited
linear gyroscope with the same footprint, intrinsic quality factors and power
budget.Comment: 17 pages, 7 figures, journal artica
- …