Wave fields measured inside a negative refractive index metamaterial

Measured spatial variations of field phase and amplitude versus position inside a wire/split ring resonator negative refractive index metamaterial are presented that show that the phase velocity inside a negative index material points toward the source and consequently that phase velocity and energy flow are reversed in such a medium. These measurements directly demonstrate the fundamental behavior of electromagnetic waves in a negative refractive index material. The same internal field measurements are also used to accurately and reliably measure the effective bulk properties of the negative index metamaterial. (C) 2004 American Institute of Physics.