Material Loss Effect on the Dispersion of Bloch Waves in Phononic Crystals
Résumé
Phononic crystals composed of lossy materials with viscosity constants proportional to the frequency are considered. Complex band structures are computed for such crystals using an extended plane wave expansion method. The effect of losses on both the real and the imaginary part of Bloch waves is investigated in the case of a two-dimensional square-lattice phononic crystal of holes in silicon. It is in particular found that losses limit the appearance of large group slownesses, or conversely small group velocities.