Acoustic confinement in superlattice cavities

Abstract

The large coupling rate between the acoustic and optical fields confined in GaAs/AlAs superlattice cavities makes them appealing systems for cavity optomechanics. We have developed a mathematical model based on the scattering matrix that allows the acoustic guided modes to be predicted in nano and micropillar superlattice cavities. We demonstrate here that the reflection at the surface boundary considerably modifies the acoustic quality factor and leads to significant confinement at the micropillar center. Our mathematical model also predicts unprecedented acoustic Fano resonances on nanopillars featuring small mode volumes and very high mechanical quality factors, making them attractive systems for optomechanical applications.

Ultrasonic and Spectroscopic Techniques for the Measurement of the Elastic Properties of Nanoscale Materials

“…New modes appear, namely the torsional ones, beside the bending or flexural ones, and the dilatational ones. In the case of circular cylinders they obey the Pochammer-Cree Equations [11,12], in which, as it often happens in cylindrically symmetric cases, Bessel functions play a crucial role. More general cases can be analyzed by the so-called xyz algorithm [13,14], which has been applied to rectangular [15], circular [16] and hexagonal [17] cases, and also to more complex cases like superlattices [18].…”

“…In particular, several branches have a non-null frequency for k ∥ ¼ 0; they correspond to modes, like e.g. the radial breathing modes, which can have a non-traveling character [12]. Furthermore, for small values of D k ∥ , the dispersion relations of most of these modes have a slope much smaller than the velocities v t or v l , meaning a low group velocity, and in some cases even a negative slope [19].…”

Phase-dependent double optomechanically induced transparency in a hybrid optomechanical cavity system with coherently mechanical driving*

“…A traditional optomechanical system is composed of an optical cavity and a mechanical resonator. With the development of the micro-and nano-fabrication techniques, it is practicable to integrate the traditional optomechanical system with other systems, including the additional mechanical resonators [12,13], superconducting microwave cavities [14], phononic [15] or photonic crystal cavities [4], piezoelectric systems [16] and charged systems [17]. Compared with the traditional optomechanical system, the photon-phonon interaction in those hybrid optomechanical systems can be controlled by not only the optical radiation pressure, but also the piezoelectric forces [4,5], Lorentz forces [18,19] or Coulombic forces [13,20].The interaction between the optical and mechanical modes can generate many interesting phenomena in the optomechanical systems, such as the optomechanical induced transparency (OMIT).…”

Optomechanical properties of GaAs/AlAs micropillar resonators operating in the 18 GHz range

“…Mechanical micropillars were previously studied both theoretically and experimentally. 5,17,18 However, the detailed description of the mechanical eigenmodes, the corresponding extremely high optomechanical coupling factors, and the optomechanical interactions with quantum emitters were not addressed before. In this Letter, we report such a comprehensive theoretical study.…”

“…1a) can be formed by enclosing a nλ/2 thick cylindrical layer in between two highly reflective acoustic DBRs, where λ is the phonon wavelength in the spacer material and n an integer number. 5,17 In this case, DBRs are obtained by stacking layers of materials with contrasting acoustic impedances, determined by the elastic properties of the materials. 19,24 For the particular material choice of GaAs/AlAs the optical and acoustic impedance contrasts are almost equal.…”