26 research outputs found
Effects of surface roughness and top layer thickness on the performance of Fabry-Perot cavities and responsive open resonators based on distributed Bragg reflectors
Optical and acoustic resonators based on distributed Bragg reflectors (DBRs)
hold significant potential across various domains, from lasers to quantum
technologies. In ideal conditions with perfectly smooth interfaces and
surfaces, the DBR resonator quality factor primarily depends on the number of
DBR pairs and can be arbitrarily increased by adding more pairs. Here, we
present a comprehensive analysis of the impact of top layer thickness variation
and surface roughness on the performance of both Fabry-Perot and open-cavity
resonators based on DBRs. Our findings illustrate that even a small,
nanometer-scale surface roughness can appreciably reduce the quality factor of
a given cavity. Moreover, it imposes a limitation on the maximum achievable
quality factor, regardless of the number of DBR pairs. These effects hold
direct relevance for practical applications, which we explore further through
two case studies. In these instances, open nanoacoustic resonators serve as
sensors for changes occurring in dielectric materials positioned on top of
them. Our investigation underscores the importance of accounting for surface
roughness in the design of both acoustic and optical DBR-based cavities, while
also quantifying the critical significance of minimizing roughness during
material growth and device fabrication processes
Nanophononic thin-film filters and mirrors studied by picosecond ultrasonics
Optimized acoustic phonon thin-film filters are studied by picosecond ultrasonics. A broadband mirror and a color filter based on aperiodic multilayers were optimized to work in the subterahertz range, and grown by molecular beam epitaxy. Time resolved differential optical reflectivity experiments were performed with pump and probe pulses incident on opposite sides of the substrate. We provide broadband transmission curves for the phonon devices. The results are in good agreement with standard transfer matrix method simulations. In addition, we analyze the effects of the free surface and the influence of an Al capping layer on the response of the aperiodic devices.Fil: Lanzillotti Kimura, Norberto Daniel. Université Pierre et Marie Curie; Francia. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Centre National de la Recherche Scientifique; FranciaFil: Perrin, B.. Université Pierre et Marie Curie; Francia. Centre National de la Recherche Scientifique; FranciaFil: Fainstein, Alejandro. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Jusserand, B.. Université Pierre et Marie Curie; Francia. Centre National de la Recherche Scientifique; FranciaFil: Lemàtre, A.. Laboratoire de Photonique et de Nanostructures; Francia. Centre National de la Recherche Scientifique; Franci
Topological Nanophononic Interface States Using High-Order Bandgaps in the One-Dimensional Su-Schrieffer-Heeger Model
Topological interface states in periodic lattices have emerged as valuable
assets in the fields of electronics, photonics, and phononics, owing to their
inherent robustness against disorder. Unlike electronics and photonics, the
linear dispersion relation of hypersound offers an ideal framework for
investigating higher-order bandgaps. In this work, we propose a design strategy
for the generation and manipulation of topological nanophononic interface
states within high-order bandgaps of GaAs/AlAs multilayered structures. These
states arise from the band inversion of two concatenated superlattices that
exhibit inverted spatial mode symmetries around the bandgap. By adjusting the
thickness ratio of the unit cells in these superlattices, we are able to
engineer interface states in different bandgaps, enabling the development of
versatile topological devices spanning a wide frequency range. Moreover, we
demonstrate that such interface states can also be generated in hybrid
structures that combine two superlattices with bandgaps of different orders
centered around the same frequency. These structures open up new avenues for
exploring topological confinement in high-order bandgaps, providing a unique
platform for unveiling and better understanding complex topological systems.Comment: 13 pages, 5 figures; supplementary information: 1 page, 1 figur
Anderson Photon-Phonon Colocalization in Certain Random Superlattices
Fundamental observations in physics ranging from gravitational wave detection to laser cooling of a nanomechanical oscillator into its quantum ground state rely on the interaction between the optical and the mechanical degrees of freedom. A key parameter to engineer this interaction is the spatial overlap between the two fields, optimized in carefully designed resonators on a case-by-case basis. Disorder is an alternative strategy to confine light and sound at the nanoscale. However, it lacks an a priori mechanism guaranteeing a high degree of colocalization due to the inherently complex nature of the underlying interference processes. Here, we propose a way to address this challenge by using GaAs/AlAs vertical distributed Bragg reflectors with embedded geometrical disorder. Because of a remarkable coincidence in the physical parameters governing light and motion propagation in these two materials, the equations for both longitudinal acoustic waves and normal-incidence light become practically equivalent for excitations of the same wavelength. This guarantees spatial overlap between the electromagnetic and displacement fields of specific photon-phonon pairs, leading to strong light-matter interaction. In particular, a statistical enhancement in the vacuum optomechanical coupling rate, go, is found, making this system a promising candidate to explore Anderson localization of high frequency (∼20 GHz) phonons enabled by cavity optomechanics. The colocalization effect shown here unlocks the access to unexplored localization phenomena and the engineering of light-matter interactions mediated by Anderson-localized states
Towards chiral acoustoplasmonics
The possibility of creating and manipulating nanostructured materials
encouraged the exploration of new strategies to control electromagnetic
properties. Among the most intriguing nanostructures are those that respond
differently to helical polarization, i.e., exhibit chirality. Here, we present
a simple structure based on crossed elongated bars where light-handedness
defines the dominating cross-section absorption or scattering, with a 200%
difference from its counterpart (scattering or absorption). The proposed chiral
system opens the way to enhanced coherent phonon excitation and detection. We
theoretically propose a simple pump-probe experiment using circularly polarized
light. In the reported structures, the generation of acoustic phonons is
optimized by maximizing the absorption, while the detection is enhanced at the
same wavelength -- and different helicity -- by engineering the scattering
properties. The presented results constitute one of the first steps towards
harvesting chirality effects in the design and optimization of efficient and
versatile acoustoplasmonic transducers.Comment: 10 pages, 6 figure
Slow light and slow acoustic phonons in optophononic resonators
Slow and confined light have been exploited in optoelectronics to enhance light-matter interactions. Here we describe the GaAs/AlAs semiconductor microcavity as a device that, depending on the excitation conditions, either confines or slows down both light and optically generated acoustic phonons. The localization of photons and phonons in the same place of space amplifies optomechanical processes. Picosecond laser pulses are used to study through time-resolved reflectivity experiments the coupling between photons and both confined and slow acoustic phonons when the laser is tuned either with the cavity (confined) optical mode or with the stop-band edge (slow) optical modes. A model that fully takes into account the modified propagation of the acoustic phonons and light in these resonant structures is used to describe the laser detuning dependence of the coherently generated phonon spectra and amplitude under these different modes of laser excitation. We observe that confined light couples only to confined mechanical vibrations, while slow light can generate both confined and slow coherent vibrations. A strong enhancement of the optomechanical coupling using confined photons and vibrations, and also with properly designed slow photon and phonon modes, is demonstrated. The prospects for the use of these optoelectronic devices in confined and slow optomechanics are addressed.Fil: Villafañe, Viviana Daniela. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Soubelet, Pedro Ignacio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Bruchhausen, Axel Emerico. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Lanzillotti Kimura, Norberto Daniel. Université Paris Sud; Francia. Centre D'etudes de Saclay; Francia. Centre National de la Recherche Scientifique; FranciaFil: Jusserand, B.. Université Pierre et Marie Curie; Francia. Centre National de la Recherche Scientifique; FranciaFil: Lemaître, A.. Université Paris Sud; Francia. Centre D'etudes de Saclay; Francia. Centre National de la Recherche Scientifique; FranciaFil: Fainstein, Alejandro. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin
Elliptical micropillars for efficient generation and detection of coherent acoustic phonons
Coherent acoustic phonon generation and detection assisted by optical
resonances are at the core of efficient optophononic transduction processes.
However, when dealing with a single optical resonance, the optimum generation
and detection conditions take place at different laser wavelengths, i.e.
different detunings from the cavity mode. In this work, we theoretically
propose and experimentally demonstrate the use of elliptical micropillars to
reach these conditions simultaneously at a single wavelength. Elliptical
micropillar optophononic resonators present two optical modes with orthogonal
polarizations at different wavelengths. By employing a cross-polarized scheme
pump-probe experiment, we exploit the mode splitting and couple the pump beam
to one mode while the probe is detuned from the other one. In this way, at a
particular micropillar ellipticity, both phonon generation and detection
processes are enhanced. We report an enhancement of a factor of ~3.1 when
comparing the signals from elliptical and circular micropillars. Our findings
constitute a step forward in tailoring the light-matter interaction for more
efficient ultrahigh-frequency optophononic devices.Comment: 10 pages, 5 figure
Dynamical optical tuning of the coherent phonon detection sensitivity in DBR-based GaAs optomechanical resonators
We present a detailed time-resolved differential reflectivity study of the electronic and the coherent phonon generation response of a GaAs optical microcavity after resonant picosecond laser pulse excitation. A complex behavior is observed as a function of laser-cavity-mode detuning and incident power. The observed response is explained in terms of the large dynamical variations of the optical cavity-mode frequency induced by the ultrafast laser excitation, related to the optical modulation of the GaAs-spacer index of refraction due to photoexcited carriers. It is demonstrated that this effect leads to a strong optical dynamical tuning of the coherent phonon detection sensitivity of the device.Fil: Sesin, Pablo Ezequiel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Soubelet, Pedro Ignacio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Villafañe, Viviana Daniela. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Bruchhausen, Axel Emerico. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Jusserand, B.. Universite de Paris VI. Institut des Nanosciences de Paris; FranciaFil: Lemaître, A.. Centre National de la Recherche Scientifique; FranciaFil: Lanzillotti Kimura, Norberto Daniel. Centre National de la Recherche Scientifique; FranciaFil: Fainstein, Alejandro. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin
Topological nanophononic states by band inversion
Nanophononics is essential for the engineering of thermal transport in
nanostructured electronic devices, it greatly facilitates the manipulation of
mechanical resonators in the quantum regime, and could unveil a new route in
quantum communications using phonons as carriers of information. Acoustic
phonons also constitute a versatile platform for the study of fundamental wave
dynamics, including Bloch oscillations, Wannier Stark ladders and other
localization phenomena. Many of the phenomena studied in nanophononics were
indeed inspired by their counterparts in optics and electronics. In these
fields, the consideration of topological invariants to control wave dynamics
has already had a great impact for the generation of robust confined states.
Interestingly, the use of topological phases to engineer nanophononic devices
remains an unexplored and promising field. Conversely, the use of acoustic
phonons could constitute a rich platform to study topological states. Here, we
introduce the concept of topological invariants to nanophononics and
experimentally implement a nanophononic system supporting a robust topological
interface state at 350 GHz. The state is constructed through band inversion,
i.e. by concatenating two semiconductor superlattices with inverted spatial
mode symmetries. The existence of this state is purely determined by the Zak
phases of the constituent superlattices, i.e. that one-dimensional Berry phase.
We experimentally evidenced the mode through Raman spectroscopy. The reported
robust topological interface states could become part of nanophononic devices
requiring resonant structures such as sensors or phonon lasers.Comment: 21 pages, 7 figure
Stimulated Forward Brillouin Scattering in Subwavelength Silicon Membranes
On-chip Brillouin scattering plays a key role in numerous applications in the
domain of signal processing and microwave photonics due to the coherent
bidirectional coupling between near-infrared optical signals and GHz mechanical
modes, which enables selective amplification and attenuation with remarkably
narrow linewidths, in the kHz to MHz range. Subwavelength periodic
nanostructures provide precise control of the propagation of light and sound in
silicon photonic circuits, key to maximize the efficiency of Brillouin
interactions. Here, we propose and demonstrate a new subwavelength waveguide
geometry allowing independent control of optical and mechanical modes. Two
silicon lattices are combined, one with a subwavelength period for the light
and one with a total bandgap for the sound, to confine optical and mechanical
modes, respectively. Based on this approach, we experimentally demonstrate
optomechanical coupling between near-infrared optical modes and GHz mechanical
modes with with 5-8 MHz linewidth and a coupling strength of GB = 1360 1/(W m).
A Stokes gain of 1.5 dB, and anti-Stoke loss of -2 dB are observed for a 6
mm-long waveguide with 35.5 mW of input power. We show tuning of the mechanical
frequency between 5 and 8 GHz by geometrical optimization, without loss of the
optomechanical coupling strength