Phononic Bandgap Micro/Nano-Mechanical Structures for Wireless Communications
and Sensing
The periodic potential caused by atoms in crystalline materials (e.g.,
semiconductors) often leads to electronic bandgaps, which are the
basis of the modern electronics. Similarly, periodic variations in
elastic (or acoustic) properties of materials can lead to phononic
(or acoustic) bandgaps (PnBGs) which are ranges of frequencies in
which no phonon (or mechanical energy) can propagate. Such
mechanically-periodic structures are called phononic crystals (PnCs).
PnCs with PnBGs can be used to efficiently confine and control
mechanical energy that enable realization of high quality resonators
and waveguides, which are the main building blocks of variety of
functional devices such as mechanical filters, multiplexers, and
demultiplexers.
Micro/nano-mechanical devices, on the other hand, are of great interest due to their
advantageous characteristics for high quality RF communication
devices and sensors. We have demonstrated, for the first
time, a low-loss PnC platform that can provide complete PnBGs in the
frequency range of interest for wireless communication and sensing
applications. Efficient resonators and waveguides are realized based
on this CMOS-compatible platform and it is shown that such PnC
structures can be combined with electronic and photonic
functionalities on the same substrate to realize compact and
efficient devices with multiple potential applications in wireless
communications and sensing.
Figure 1. (Left) Side-view SEM image of a fabricated PnC structure with the
transducers electrodes, (middle) band structure of elastic waves
propagating through the PnC slab in different directions and
wavevectors, and (right) measured normalized transmission through the
fabricated PnC slab showing great agreement with the theoretical
predictions.
S. Mohammadi, A.A. Eftekhar, W.
D. Hunt, and A. Adibi, “High-Q micro-mechanical resonators in a
two-dimensional phononic crystal slab,” Appl. Phys. Lett. 94,
051906 (2009).
S. Mohammadi, A.A. Eftekhar, A.
Khelif, W. D. Hunt, and A. Adibi, “Evidence of large
high-frequency complete phononic band gaps in silicon phononic
crystal plates,” Appl. Phys. Lett. 92, 221905-1-3 (2008).
S. Mohammadi, A. A.
Eftekhar, A. Khelif, H. Moubchir, R. Westafer, W. D. Hunt, and A.
Adibi, “Complete phononic bandgaps and bandgap maps in
two-dimensional silicon phononic crystal plates,” Electron. Lett. 43, 898-9 (2007).
A. Khelif, B. Aoubiza, S.
Mohammadi, A. Adibi, and V. Laude, “Complete band gaps in
two-dimensional Phononic Crystal slabs,” Phys. Rev. E, 74, 046610 (2006).
