Nanomechanics Research Group
NTT Basic Research Laboratories
3-1, Morinosato Wakamiya, Atsugi-shi, Kanagawa, 243-0198 Japan

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Micro/Nano-electromechanics  Electromechanical phononic crystals  Semiconductor optomechanics 


Electromechanical phononic crystals
Recent Activities
Phonon propagation dynamics in band-engineered one-dimensional phononic crystal waveguides
D. Hatanaka, A. Dodel, I. Mahboob, K. Onomitsu, and H. Yamaguchi , New J. Phys. 17 113032 (2015) @
The phonon propagation dynamics in a phononic crystal waveguide, realized via a suspended one-dimensional membrane array with periodic air holes, is investigated as function of its geometry. The bandstructure of the phononic crystal waveguide can be engineered by modifying the characteristics of the phonon waves by varying the waveguide width and the pitch of the air holes. This enables the phonon transmission bands, the bandgaps, the velocity and the nonlinear dispersion in the phononic crystal to be controlled. Indeed the engineered bandstructure can even be tuned to sustain multiple phonon modes in a given branch which while being spectrally degenerate can be temporally resolved via their differing group velocities. Furthermore, the ability to tune the bandstructure and thus the nonlinear dispersion can be harnessed to efficiently activate nonlinear phenomena such as mechanical four wave mixing. This systematic study reveals the key geometric parameters that enable the phonon transport in phononic crystal waveguides to be fully controlled.
Mechanical random access memory in a phonon circuit
Daiki Hatanaka, Imran Mahboob, Koji Onomitsu, and Hiroshi Yamaguchi, Applied Physics Express 7, 125201 (2014)
The phonon propagation dynamics in a phononic crystal waveguide, realized via a suspended one-dimensional membrane array with periodic air holes, is investigated as function of its geometry. The bandstructure of the phononic crystal waveguide can be engineered by modifying the characteristics of the phonon waves by varying the waveguide width and the pitch of the air holes. This enables the phonon transmission bands, the bandgaps, the velocity and the nonlinear dispersion in the phononic crystal to be controlled. Indeed the engineered bandstructure can even be tuned to sustain multiple phonon modes in a given branch which while being spectrally degenerate can be temporally resolved via their differing group velocities. Furthermore, the ability to tune the bandstructure and thus the nonlinear dispersion can be harnessed to efficiently activate nonlinear phenomena such as mechanical four wave mixing. This systematic study reveals the key geometric parameters that enable the phonon transport in phononic crystal waveguides to be fully controlled.
Phonon waveguides for electromechanical circuits
D. Hatanaka, I. Mahboob, K. Onomitsu and H. Yamaguchi , Nature Nanotech. 9, 520 (2014) @
Nanoelectromechanical systems (NEMS), utilizing localized mechanical vibrations, have found application in sensors, signal processors and in the study of macroscopic quantum mechanics. The integration of multiple mechanical elements via electrical or optical means remains a challenge in the realization of NEMS circuits. Here, we develop a phonon waveguide using a one-dimensional array of suspended membranes that offers purely mechanical means to integrate isolated NEMS resonators. We demonstrate that the phonon waveguide can support and guide mechanical vibrations and that the periodic membrane arrangement also creates a phonon bandgap that enables control of the phonon propagation velocity. Furthermore, embedding a phonon cavity into the phonon waveguide allows mobile mechanical vibrations to be dynamically switched or transferred from the waveguide to the cavity, thereby illustrating the viability of waveguide–resonator coupling. These highly functional traits of the phonon waveguide architecture exhibit all the components necessary to permit the realization of all-phononic NEMS circuits.
A phonon transistor in an electromechanical resonator array
D. Hatanaka, I. Mahboob, K. Onomitsu, and H. Yamaguchi , Appl. Phys. Lett. 102, 213102 (2013) @
An electromechanical resonator array is developed that consists of 5 mechanically coupled membranes. Mechanical excitation of the array results in 2 types of oscillations, an extended mechanical oscillation that propagates through all 5 membranes and a localized mechanical oscillation that is confined to just some of the membranes. The dynamic interaction of these 2 types of oscillations is used to implement a transistor in this phononic system.
An electromechanical membrane resonators
D. Hatanaka, I. Mahboob, H. Okamoto, K. Onomitsu and H. Yamaguchi , Appl. Phys. Lett. 101, 063102 (2012)@
An electrically active membrane-based mechanical resonator was fabricated from a GaAs/AlGaAs heterostructure. The mechanical motion of the membrane was piezoelectrically excited and detected. The piezoelectric transducer could also excite a range of resonance modes in the membrane that were identified and mapped via optical interferometry. Furthermore, the various mode shapes combined with the piezoelectric transduction could be used to execute mechanical-logic-gates. The development of an electrically active membrane-based mechanical resonator paves the way towards responsive electromechanical detectors and highly functional opto-electro-mechanical systems.



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