Laser printing of silver and silver oxide

We show that direct laser writing in aqueous silver nitrate with a λ = 1030 nm femtosecond laser results in the deposition of a mixture of silver oxide and silver, in contrast to the pure silver deposition previously reported with 780 nm femtosecond direct laser writing. However, adding photoinitiator prevents silver oxide formation in a concentration-dependent manner. As a result, the resistivity of the material can also be controlled by photoinitiator concentration with resistivity being reduced from approximately 9e-3 Ωm to 3e-7 Ωm. Silver oxide peaks dominate the X-ray diffraction spectra when no photoinitiator is present, while the peaks disappear with photoinitiator concentrations above 0.05 wt%. A THz polarizer and metamaterial are printed as a demonstration of silver oxide printing.