  2D and 3D micro/nano fabrication based on two-photon polymerization (TPP) has
emerged as a strong contender for additive manufacturing for wide variety of
applications. In this manuscript we report one step patterning of structurally
stable, subwavelength 2D and 3D gold nanostructures using femto-second laser by
incorporating single photon photoinitiator only in pure and metal precursor
doped polymers. The metal polymer composite nanostructures are written directly
by in-situ reduction of gold precursor within the photoresist using
femto-second laser irradiation. The photo-initiator triggers the reduction of
gold precursor and induces simultaneous polymerization of the photoresist based
on two-photon absorption phenomenon. Diffraction gratings with varied loading
of gold precursors in photoresist have been fabricated and characterized by
measuring their diffraction efficiencies in the infrared region. Minimum line
width of 390 nm has been achieved for 5 wt% gold loaded polymers. Systematic
studies of the effect of laser power, metal precursor loading etc. on the
line-widths have also been performed. These investigations are expected to pave
way for exploration of new material combinations for development of simple
fabrication for fabrication of metal composite functional structures at
significantly low cost and with high-throughput.
