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

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

Mesoporous Thin Films for Acoustic Devices in the Gigahertz Range

The coherent manipulation of acoustic waves on the nanoscale usually requires multilayers with thicknesses and interface roughness defined down to the atomic monolayer. This results in expensive devices with predetermined functionality. Nanoscale mesoporous materials present a high surface-to-volume ratio and tailorable mesopores, which allow the incorporation of chemical functionalization to nanoacoustics. However, the presence of pores with sizes comparable to the acoustic wavelength is intuitively perceived as a major roadblock in nanoacoustics. Here, we present multilayered nanoacoustic resonators based on mesoporous SiO2 thin films showing acoustic resonances in the 5-100 GHz range. We characterize the acoustic response of the system using coherent phonon generation experiments. Despite resonance wavelengths comparable to the pore size, we observe for the first time well-defined acoustic resonances. Our results open the path to a promising platform for nanoacoustic sensing and reconfigurable acoustic nanodevices based on soft, inexpensive fabrication methods.Fil: López Abdala, Nicolás Andrés. Universidad Nacional de San Martin. Instituto de Nanosistemas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Esmann, Martin. Université de Paris-Saclay; Francia. Centre National de la Recherche Scientifique; FranciaFil: Fuertes, María Cecilia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes.; ArgentinaFil: Angelome, Paula Cecilia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes | Comision Nacional de Energia Atomica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia. Unidad Ejecutora Instituto de Nanociencia y Nanotecnologia - Nodo Constituyentes.; ArgentinaFil: Ortiz, Omar. Université de Paris-Saclay; Francia. Centre National de la Recherche Scientifique; FranciaFil: Bruchhausen, Axel Emerico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Pastoriza, Hernan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Perrin, Bernard. Sorbonne University; Francia. Centre National de la Recherche Scientifique; FranciaFil: Soler Illia, Galo Juan de Avila Arturo. Universidad Nacional de San Martin. Instituto de Nanosistemas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lanzillotti Kimura, Norberto Daniel. Université de Paris-Saclay; Francia. Centre National de la Recherche Scientifique; Franci