Loss-compensated broadband epsilon-near-zero metamaterials with gain media

The concept of loss-compensated broadband epsilon-near-zero metamaterials consisting of step-like metal-dielectric multilayer structures doped with gain media is proposed based on the combination of the Milton representation of the effective permittivity and the optical nonlocality due to the metal-dielectric multilayer structures. With the loss compensation by gain media, broadband epsilon-near-zero metamaterials possesses significantly low material loss in optical frequency range, leading to superior broadband electromagnetic properties for realizing unique functional optical devices, such as the demonstrated prisms for broadband directional emission and S-shaped lenses for phase front shaping.