High aspect ratio submicrometer two-dimensional structures fabricated by one-photon absorption direct laser writing

We have demonstrated a simple technique, based on a combination of a low cost one-photon elaboration method in a very low absorption regime (LOPA) and a tightly focusing optical system, to fabricate submicrometer 2D and 3D structures. A simple continuous-wave laser at 532 nm with only a few milliwatts allowed to fabricate high-aspect-ratio 2D pillars arrays in a commercial SU8 photoresist. The diameter of pillars is about 300 nm and the aspect ratio is as high as 7. This direct laser writing technique based on the LOPA approach is potentially a breakthrough: it is very simple, compact and low cost, while it allows to achieve the same results as those obtained by the two-photon absorption technique.