Investigation of the optimal processing parameters for picosecond laser-induced microfabrication of a polymer-ceramic hybrid material

This paper reports the effect of different process parameters on the resolution of direct laser writing by two-photon polymerization (2PP) with a low-cost Nd:YAG picosecond laser. Microstructures were fabricated from the hybrid polymer-ceramic material Ormocomp (R) and the impact of varying the laser beam focus position, average laser power and scanning speed were investigated in detail with scanning electron microscopy and atomic force microscopy imaging. With the appropriate laser beam focus settings, suspended structures could be fabricated. The laser intensity range of the so-called polymerization window and damage zone are reported along with the scanning speed range for producing uniform polymer lines. It is shown that very high resolution is achievable with this affordable picosecond laser 2PP system with feature sizes comparable to those previously reported for costly femtosecond laser systems. The discovered relationships between the process parameters and structure dimensions enable the design and fabrication of both 3D microstructures and nanometer scale surface features.