Micropillar Resonators for Optomechanics in the Extremely High 19–95-GHz Frequency Range

Abstract

Strong confinement, in all dimensions, and high mechanical frequencies are highly desirable for quantum optomechanical applications. We show that GaAs/AlAs micropillar cavities fully confine not only photons but also extremely high frequency (19-95 GHz) acoustic phonons. A strong increase of the optomechanical coupling upon reducing the pillar size is observed, together with record room-temperature Q-frequency products of 10^{14}. These mechanical resonators can integrate quantum emitters or polariton condensates, opening exciting perspectives at the interface with nonlinear and quantum optics.

Interactive optomechanical coupling with nonlinear polaritonic systems

“…As a potential platform for the realization of interactive coupling we propose a hybrid optomechanical semiconductor system where a cavity mode is strongly coupled to an excitonic mode in a quantum well [28,[45][46][47][48][49][50], forming polaritonic modes. There, it appears due to the position dependence of the excitonic fraction (Hopfield coefficient) of polaritons.…”

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

“…19,25 Hence, the micropillar is an optical resonator, confining photons in the near infrared range (~ 325 THz) and, simultaneously a mechanical resonator, confining acoustic phonons of around 18 GHz, both photons and phonons having the same wavelength λ ~ 250 nm in GaAs. 5 There are, however, two important differences between the optical and mechanical behaviors of the system. Firstly, phonons are subject to total reflection due to the incapability of the semiconductor/vacuum interfaces to transmit mechanical vibrations and secondly, different mechanical directions of vibration are coupled through the Poisson's ratio.…”

“…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.…”

“…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][7][8] in optical simulations based on quantum well cavity polaritons, [9][10][11][12] and in solid state quantum optics where single quantum dots constitute highly coherent artificial atoms.…”

“…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.…”