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

Abstract

Recent experiments demonstrated that GaAs/AlAs based micropillar cavities are promising systems for quantum optomechanics, allowing the simultaneous three-dimensional confinement of nearinfrared photons and acoustic phonons in the 18-100 GHz range. Here, we investigate through numerical simulations the optomechanical properties of this new platform. We evidence how the Poisson's ratio and semiconductor/vacuum boundary conditions lead to very distinct features in the mechanical and optical three dimensional confinement. We find a strong dependence of the mechanical quality factor and strain distribution on the micropillar radius, in great contrast to what is predicted and observed in the optical domain. The derived optomechanical coupling constants g 0 reach ultra-large values in the 10 6 rad/s range.The study of mechanical systems in their quantum ground state motivates the development of novel optomechanical resonators with frequencies higher than a few GHz. [1][2][3][4] In this particular frequency range, standard cryogenic techniques become sufficient to reach the quantum regime without relying on additional sideband optical cooling. Recently, GaAs/AlAs pillar microcavities have been presented 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.5 Well known for their optical properties, micropillar cavities confine light in the three directions of space. They are widely used in non-linear optics, taking advantage of the strong optical non-linearities in GaAlAs semiconductors, 6-8 in optical simulations based on quantum well cavity polaritons, 9-12 and in solid state quantum optics where single quantum dots constitute highly coherent artificial atoms. 13,14 This diversity of optical applications opens a wide range of possibilities in the field of optomechanics, such as the creation of nonclassical and entangled photonic and mechanical states, 1 and the development of hybrid quantum devices that interface usually incompatible degrees of freedom by means of phonons. 15,16 Their properties as optomechanical resonators thus need to be explored to determine the acoustic confinement mechanism, and the optimal optomechanical coupling conditions. Mechanical micropillars were previously studied both theoretically and

Scaling rules in optomechanical semiconductor micropillars

“…Additionally, the realization of high-frequency optomechanical systems is highly desirable for metrology applications [5] and for ultrafast information processing [6,7]. As part of this pursuit, micropillar resonators operating at ultrahigh frequencies (greater than 10 GHz) and presenting strong optomechanical interactions and state-of-the-art Q-frequency products have been reported recently [8,9]. This frequency range, however, comes together with critical challenges.…”

Phononic Crystal Made of Multilayered Ridges on a Substrate for Rayleigh Waves Manipulation

“…Moreover, a phononic ridge can be used to excite high QF surface phonons, which can then couple with external photons. Very recently, Anguiano et al [63] and Lamberti et al [64] demonstrated the confinement of both phonons and photons with strong optomechanic coupling in a composite multilayered GaAs/AlAs micopillar. The composite pillar-based system would be a promising structure for observing quantum optomechanic phenomena, and even for integration into a biosensing platform for instance, to increase device sensitivity.…”

Brillouin scattering in hybrid optophononic Bragg micropillar resonators at 300 GHz

“…In the vertical direction, the resonant cavity confinement leads to an exponentially decaying envelope of the optical mode in both DBRs. In the radial direction, the refractive index contrast between the semiconductor materials and vacuum leads to an additional in-plane confinement of the mode with a Bessel -type envelope [34][35][36] much like for an optical fiber. To probe the Brillouin spectrum of individual micropillars, an incident laser beam (mode hop -free cw Ti:Sa laser M2 SolsTiS) resonant with the fundamental optical micropillar mode is focused to a spot size of roughly 10µm (FWHM) on the sample surface and centered on a pillar.…”