Large area light propagation in quasi-zero average refractive index metamaterial based on photonic crystals.

New possibilities in materials properties has been opened by negative refraction effect. In particular for optics and photonics, Negative Index Materials (NIMs) open to possibility to realize superlens where the amplification of evanescent components permit to recover images with subwavelength details. Pendry proposed complementary media in order to overcome the large absorption in present NIMs. Nevertheless, Li evidenced how alternating positive and negative refractive index material a gap appears when the zero average refractive index is obtained. Here, we present a complementary medium obtained by alternating air layers and photonic crystal layers showing negative refraction at l=1.55 µm. The layers lengths was designed to have a not perfect zero average refractive index structure. The experimental results show the image transfer of the source achieved over such large-scale metamaterials. Surprisingly any apparent modification of the propagating light is detected along a 2 mm distance, which represents more than thousand time the wavelength l=1.55 µm of this experiment. Besides, in this work we experimentally show how the propagation length depend on the wavelength.