Negative refraction and plano-concave lens focusing in one-dimensional   photonic crystals
  Negative refraction is demonstrated in one-dimensional (1D) dielectric photonic crystals (PCs) at microwave frequencies. Focusing by plano-concave lens made of 1D PC due to negative refraction is also demonstrated. The frequency-dependent negative refractive indices, calculated from the experimental data matches very well with those determined from band structure calculations. The easy fabrication of one-dimensional photonic crystals may open the door for new applications. 
P. Vodo, W. T. Lu, Y. Huang, and S. Sridhar