Nanophononics, the control of vibrations, sound and heat at the nanoscale, is essential for the engineering of thermal transport in electronic devices and for the manipulation of mechanical resonators in their quantum regime. It is also a promising new route in quantum communications using phonons as carriers of information. Our objective is to engineer opto-phononic systems to manipulate light, charge and sound at the nanoscale and their mutual interactions. We manipulate light-matter interactions in confined systems like microcavities, quantum dots, plasmonic and dielectric nanostructures in the classical and quantum regimes unveiling new physical phenomena and applications.
We are currently exploring the following research lines:
Coherent acoustic phonons modulate optical, electronic and mechanical properties at ultrahigh frequencies and can be exploited for applications such as ultratrace chemical detection, ultrafast lasers and transducers. We study two novel platforms in nanophononics: acousto-plasmonic structures and mesoporous resonators.
1. Owing to their large absorption cross-sections and high sensitivities, nanoplasmonic resonators can be used to generate coherent phonons up to terahertz frequencies, opening a new field of research: acousto-plasmonics.
2. Porous materials are good acoustic absorbers and widely used for acoustic isolation. In nanophononics and nanomechanics the need for atomic-flat interfaces and well defined nanometric thicknesses usually perevented the use of porous systems. The possibility of integrating mesoporous materials in ultra-high frequency nanomechanical systems remained an unexplored subject, regardless of its huge potential.
Acoustic phonons represent a versatile platform for the study of wave dynamics and localized excitations featuring two main advantages with respect to the electronic and optical counterparts: First, their short wavelengths (few nanometers at 100 GHz-THz frequencies) allow the experimental implementation of very large systems which may be considered infinite for all practical means. Second, the relatively slow speed of sound renders the amplitude and phase of the acoustic wave fully accessible. Topological acoustics, Anderson co-localization of acoustic phonons and visible photons, Bloch oscillations are a few examples of the physics explored in this research line.
The study of mechanical systems in their quantum ground state motivates the development of novel optomechanical resonators with frequencies higher than a few GHz. In this particular frequency range, standard cryogenic techniques become sufficient to reach the quantum regime without relying on additional sideband optical cooling. Recently, we presented GaAs/AlAs pillar microcavities as new optomechanical resonators performing in the unprecedented 18-100 GHz mechanical frequency range, showing highly promising features such as state-of-the-art quality factor-frequency products. We explore novel phonon confinement strategies as well as innovative measuring techniques.
Semiconductor micropillars deterministically coupled to quantum dots have been used to fabricate near-optimal single photon sources. In this research line, in close collaboration with the team of Pr. Senellart we work towards extending the CQED phenomena by using confined acoustic phonons in the same micropillars. The demonstration of the phononic Purcell effect is our first scientific target.