While researching whether or not
matter interacts with the
magnetic component of light,
Victor Veselago (1967) envisioned the possibility of refraction with a negative sign, according to
Maxwell's equations. A
refractive index with a negative sign is the result of
permittivity, ε < 0 (less than zero) and
magnetic permeability, μ < 0 (less than zero). In the mid-1990s, metamaterials were first seen as potential technologies for applications such as
nanometer-scale imaging and
cloaking objects. For example, in 1995, Guerra fabricated a transparent grating with 50 nm lines and spaces, and then coupled this (what would be later called) photonic metamaterial with an immersion objective to resolve a silicon grating having 50 nm lines and spaces, far beyond the diffraction limit for the 650 nm wavelength illumination in air. And in 2002, Guerra et al. published their demonstrated use of subwavelength nano-optics (photonic metamaterials) for optical data storage at densities well above the diffraction limit. As of 2015, metamaterial antennas were commercially available. First demonstration of a negative index of refraction in the optical range was done by
Vladimir M. Shalaev et al, using pair of metal nanorods (sometimes conversationally referred to as Shalaev's chopsticks). Negative permeability was achieved with a
split-ring resonator (SRR) as part of the subwavelength cell. The SRR achieved negative permeability within a narrow frequency range. This was combined with a
symmetrically positioned
electric conducting post, which created the first negative index metamaterial, operating in the microwave band. Experiments and simulations demonstrated the presence of a left-handed propagation band, a left-handed material. The experimental confirmation of negative
index of refraction using SRRs occurred soon after, also at microwave frequencies. ==Negative permeability and negative permittivity==