Visualization of negative refraction in phononic crystal using pulsed light source

In recent years, the phononic crystal gets a lot attention because the size of phononic crystal is larger than that of photonic crystal for the relation between the wavelength of sound and that of light. Phononic crystal has many characteristics. Among them, we regard the negative refraction in phononic crystal. The negative refraction has a potential for the application to acoustical flat lens. We visualize the negative refraction by using optical method. In addition, the phononic crystals are made by self-produced. Therefore, they have some deviances of lattices in the crystals. We verified the influence depending on the deviances of lattices by using finite element method (FEM). As results, it is verified that the deviance of lattice have an influence on the behavior of wave propagation in phononic crystals. The behaviors are very different depending on the position of deviation of lattice. Also, we consider that it has possibilities of more effective focus method for the acoustical flat lens using the influence of deviances in a positive way.