Two photon absorption coefficients and processing parameters for photoresists

The two photon absorption (TPA) process is currently used to write high resolution microstructures for a variety of applications. Key parameters required to predict the final structure formation for this process are experimentally determined and reported in this article for two commercially available resists, Ormocore and SU-8. The measured TPA coefficients measured at 800 nm for Ormocore and SU-8 are 27 ± 6 and 28 ± 6 cm TW⁻¹, respectively. For Ormocore and SU-8 the dose required to write 35 and 50 μm high structures, respectively, were 54 ± 8 and 3.5 ± 0.5 J cm⁻³, respectively, and the measured contrasts were 15 ± 2 μm per decade J⁻¹ cm³ and 55 ± 8 μm per decade J⁻¹ cm³, respectively.