Investigation into ultimate resolution by femtosecond laser two-photon fabrication technique

One 3-dimensional piezostage and one rotation stage are used in two-photon fabrication systems for controlling expose time and expose power with precision as high as 0.02 ms and 7 pW respectively. By accurate controlling expose time and laser power near polymerization threshold, 35 nm and 45 nm polymer line on cover glass are obtained respectively, which is only 1/22 and 1/17 of the laser wavelength used for fabrication. These results are the highest linewidth resolution obtained by two photon fabrication on cover glass until now. It is revealed that linewidth resolution can be improved efficiently with ultra-small reduction of the expose time or expose power near polymerization threshold. The further possible improvement for resolution of two-photon process was analyzed in the paper.