Nano-fabrication of surface relief gratings on azo dye films utilizing interference of evanescent waves on prism

Nano-patterns were investigated on azo dye thin films exposed by an interference of evanescent waves propagating on a prism surface. The patterns strongly depended upon polarization of the incident laser beams forming electric field vectors of the evanescent waves in the vicinity of the prism surface. Line structures of surface relief gratings (SRGs) were clearly inscribed by selecting s-polarization of the incident light. The cyclic pattern of the lines was approximately 210 nm that was smaller than a half of the wavelength of the incident laser at 488 nm. Any line patterns were not obtained using p-polarization of the light, but nano-dot patterns were fabricated on azo dye films. This technique based on molecular migration due to evanescent waves is thought to be very useful for nano-device processing and future device applications.