Fused LiNbO₃-(Al)GaAs hybrids for quantum dots optomechanics

Surface acoustic waves (SAW) are a useful tool to control the emission of quantum dots (QDs). In particular, SAWs enable the injection of charge carriers into the dot or the modulation of their energy levels [1,2,3]. Here, we explore the possibility to enhance the interaction between the SAW and the QDs by transferring them on a strong piezoelectric LiNbO₃ substrate by epitaxial lift-off [4]. By employing multiharmonic transducers, we generate SAWs on LiNbO₃ over a wide range of radiofrequencies. We monitor their coupling to and propagation across the semiconductor membrane, both in the electrical and optical domain. We demonstrate the enhanced optomechanical tuning of the embedded QDs with increasing frequencies. This effect is verified by finite element modelling of our device geometry and attributed to an increased localization of the acoustic field within the semiconductor membrane [5]. The results of our study clearly show the large potential of our hybrid platform to integrate complex phononic and optomechanical circuitry with integrated QDs to study sound-matter coupling.
[1] Appl. Phys. Lett. 93, 081115 (2008), [2] Nano Lett. 10, 3399-3407 (2010), [3] Phys. Rev. B 88, 085307 (2013), [4] Appl. Phys. Lett. 106, 013107 (2015), [5] J. Phys. D: Appl. Phys. 50, 43LT01 (2017)