Fabrication of silver nano-rings using photo-reduction induced by femtosecond pulses

Fabrication of silver nano-rings using direct laser writing lithography technique is reported. Generation of metallic silver regions in thin silver-containing films deposited on glass substrates is achieved via the photo-reduction of silver ions induced by multi-photon absorption of tightly focused femtosecond laser pulses. Ring-shaped sub-micrometer sized metallic regions composed of silver were formed using circularly polarized laser beam for optical exposure. Possibilities to control the diameter and width of the nano-rings by changing the laser power and exposure time are demonstrated. This method may be useful for fast patterning of large plasmonic substrates composed of silver nano-rings.