Surface plasmon interference pattern on the surface of a silver-clad planar waveguide as a sub-micron lithography tool

A new sub-micron photolithography tool has been realized by utilizing the interference of surface plasmon waves(SPWs) on the near surface of a silver(Ag)-clad ultraviolet(UV) planar waveguide.A laser beam with a wavelength of 325 nm was incident into the waveguide core,and suffered a series of total internal reflections on the interfaces between the waveguide core and the cladding layers.The incident light and the reflected light induced two beams of SPWs traveling in contrary directions,which interfered with each other and formed a standing wave as a sub-micron photolithography tool.A near-field scanning optical microscope(NSOM) was employed to measure the intensity distribution of the stationary wave field of the near surface of the Ag layer of the waveguide,anastomosed with theoretical values acquired by use of finite difference time domain(FDTD) simulations.And with this sub-micron photolithography tool a SMG with a period of 79.3 nm,in good agreement with the theoretical value of 80.1 nm,was inscribed on the surface of a self-processing hybrid SiO2/ZrO2 solgel film for the first time.