Waveguiding in two-dimensional piezoelectric phononic crystal plates

Abstract

We investigate the possibility of designing phononic crystal-based devices for telecommunication applications using materials commonly employed in microfabrication. We focus our attention on a phononic crystal made of a square array of cylindrical holes drilled in an active piezoelectric PZT5A matrix. Two different structures are considered, namely, a freestanding phononic crystal plate and a plate deposited on a silicon substrate. The geometrical characteristics of the phononic crystal plates ͑lattice parameter and thickness͒ were chosen to ensure the existence of an absolute band gap around 1.5 GHz; a common frequency in radio frequency telecommunications. Computations of the dispersion curves of these active structures were conducted with the help of the finite element method. We demonstrate the existence of absolute band gaps in the band structure of the phononic crystal plates and, then, the possibility of guided modes inside a linear defect created by removing one row of air holes in the phononic crystal. In the case of the supported phononic crystal plates, we show the existence of an absolute forbidden band in the plate modes when the thickness of the substrate significantly exceeds the plate thickness. We discuss the conditions to realize waveguiding through a linear defect inside the supported plate. The present work provides evidences that phononic crystal properties can be integrated with existing silicon based microdevice technology.

Surface acoustic waves in finite slabs of three-dimensional phononic crystals

“…Nowadays, the research on phononic crystals increasingly focuses on nonperiodic structures and related phenomena such as disorder effects, sound focusing, waveguiding, etc. In this framework, the study of surface elastic waves associated with the surface of a semi-infinite phononic crystal, or of the plate modes in a finite-thickness phononic crystal, has attracted a lot of attention in recent years, in the domain of basic research, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] but also because of its promise in technological applications, mostly in telecommunications, 18,19 in microelectromechanical systems, 20 etc. On the other hand the investigation of gaps in the frequency spectra of the abovementioned finite structures is important again, as it is the base for the development of defect or guided modes in a region free of modes.…”

“…The relevant literature is so far almost exclusively focused on systems of 2D phononic crystals, which have been extensively studied theoretically [2][3][4][5][6][7][8][9][10] and experimentally. [11][12][13][14][15][16] In these studies cases of both semi-infinite [2][3][4][5][6][14][15][16] and finite [7][8][9][10][11][12][13] slabs are considered. The corresponding 3D systems remain from this point of view practically unexplored, apart from one exception, 17 as far as we know.…”

Phononic crystals and manipulation of sound

“…The second part of the paper is devoted to the acoustic wave propagation in phononic crystal of finite height such as free standing or supported plates [10][11][12]. These structures have attracted a great deal of attention during the last few years, in particular to investigate the possibility of ab-…”

Ultrasonic transmission through periodically perforated plates

“…On the other hand, not only plates made of conventional isotropic or anisotropic solids have been subject of research, but also piezoelectric [124] and ferroelectric [125] materials including temperature variation issues of the latter [126].…”

“…at small scales for Microelectromechanical systems (MEMS), most practical realizations need a substrate to be implemented. The effect of a solid substrate on the PhP is considered for band-gap formation and waveguiding in [124,127,128,129,130,131,132,133].…”