“…Different approaches have been made to synthesize the negative refractive index materials. These include fabricating a multilayer metal-dielectric stack by using focused ion-beam milling [79], printed circuit board technology [80], self assembly approach [81,82], fabricating regular arrays of metal pillars by high-resolution electron-beam lithography on a glass substrate [83,84], and by sol-gel technique [85]. Regular arrays of gold and silver pillars fabricated by high resolution electron-beam lithography or by ion-implantation, both on glass substrates have been reported to have negative refractive index.…”