Abstract:
Phoxonic structures (also called phononic-photonic) consist of a periodicity in the refractive
index and acoustic impedance in a systematic way and confine acoustic and electromagnetic
waves.They lead to new acousto-optical or optomechanical applications. The main objective
of this work is to model a crystal that allows the coupling of photonic and phononic band gap
phenomena in order to study the acousto-optical interactions that can occur in
anoptomechanical cavity by inserting a silicon disc of radius ri. insideinclusions. This analogy
between optics and acoustics allows us, on one hand, to increase the efficiency of the
insulators and on the other hand, to improve the acoustic characteristics and optimize the
electromechanical performances of certain types of transducers used in medical imaging. The
simulation of the gap according to the geometric parameters using the COMSOL
MULTIPHYSICS software based on the finite element method has shown that the internal
radius value ri = r/2 is optimal to obtain a maximum phononic and photonic (TM) width of
75% and 15% simultaneously. This opening obtained from Silicon remains the best compared
to gaps of aluminum, SiO2 and epoxy. Finally a thorough study on transmission (results in
accordance with the literature) was carried out and has shown another form of investigating of
the band gap that confirmed the choice of the inner radius value.
The width of the absolute band gap obtained by inserting an internal disc withoptimized
radius ri = r/2insures the presence of a large number of well localized modes with a high
quality factor which can reach 105. In conclusion, the phoxonic cavity designed with a high
quality factor can be used to improve the acousto-optical interaction.
