Negative refraction experiments in soft 3D metafluids

Physics of negative refraction has been intensively studied since the 2000s. Negative refraction is usually evidenced by a Snell’s law experiment using a prism shaped negative-index metamaterial wedge. The first experimental verification of negative index of refraction was reported in 2D resonant structures at microwave frequencies [1]. A few years later, negative refraction was demonstrated in 2D and 3D resonant optical metamaterials [2]. In acoustics, the first experimental demonstration of negative refraction was reported in 3D (non resonant) phononic crystals at ultrasonic frequencies [3]. However, 3D acoustic (random) metamaterials should also offer the possibility to explore this exotic phenomenon since the first 3D locally resonant metamaterial with a negative index has been recently demonstrated [4]. In this talk, we will report on negative refraction experiments performed in these soft 3D metafluids composed of macro-porous micro-beads randomly dispersed in a water-based gel-matrix. Negative refr...