Abstract
AbstractThe optomechanical coupling of quantum dots and flexural mechanical modes is studied in suspended nanophononic strings. The investigated devices are designed and monolithically fabricated on an (Al)GaAs heterostructure. Radio frequency elastic waves with frequencies ranging between and 400 MHz are generated as Rayleigh surface acoustic waves on the unpatterned substrate and injected as Lamb waves in the nanophononic string. Quantum dots inside the nanophononic string exhibit a 15‐fold enhanced optomechanical modulation compared to those dynamically strained by the Rayleigh surface acoustic wave. Detailed finite element simulations of the phononic mode spectrum of the nanophononic string confirm that the observed modulation arises from valence band deformation potential coupling via shear strain. The corresponding optomechanical coupling parameter is quantified to . This value exceeds that reported for vibrating nanorods by approximately one order of magnitude at 100 times higher frequencies. Using this value, a derived vertical displacement in the range of 10 nm is deduced from the experimentally observed modulation. The results represent an important step toward the creation of large scale optomechanical circuits interfacing single optically active quantum dots with optical and mechanical waves.
Highlights
The optomechanical coupling of quantum dots and flexural mechanical phononic technologies of industrial relevance[2] and have recently attracted modes is studied in suspended nanophononic strings
quantum dots (QDs) can be integrated in fully suspended photonic crystal membranes with SAWtunable circuit elements[18,19] enabling the dynamic control of light–matter interaccreation of large scale optomechanical circuits interfacing single optically tions at gigahertz frequencies.[20]
Surface acoustic waves (SAWs) are one of the very few excited in these membranes are stress-neutral in the center plane of the membrane, that is, the volumetric strain vanishes
Summary
In contrast to QDs strained by Rayleigh waves, the two dots inside the nanophononic string show strong enhancement of the optomechanical modulation over a wide frequency band. We demonstrate that QDs can be coupled to flexural modes of a suspended nanophononic string and observe a strong enhancement of the optomechanically induced spectral modulation at radio frequencies exceeding 400 MHz, important to reach the resolved sideband regime.[10] In this regime parametric transduction becomes accessible and enables the implementation of hybrid quantum dot optomechanical transduction and control schemes. Promise high fidelity quantum control schemes, or QDs forming in nanowires.[12,13,17,49,50] our work marks a first important step to interface optomechanical crystals with engineered dispersions of phonons and photons and operation frequencies in the GHz domain.[51,52] the observed optomechanical coupling arises exclusively from shear strain modulating the valence band of the semiconductor, a rarely studied effect compared to normal strain coupling
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