3D print­ing at the nanoscale is an estab­lished technol­ogy. However, for certain appli­ca­tions it is still consid­ered prohib­i­tively slow. Conven­tion­ally, laser beam pulses illumi­nate one volume element after another in a light-sensi­tive ink, build­ing up the desired object. In this project, each laser pulse is holograph­i­cally shaped and illumi­nates a large number of voxels in paral­lel. This technique promises orders of magni­tude faster print­ing and shall be demon­strated for complex 3D structures.

Three-dimen­sional print­ing with resolu­tion at the nanoscale offers numer­ous appli­ca­tions in various fields, such as photon­ics, biology and micro-robot­ics. One of the main challenges prevent­ing an even more widespread use of this technol­ogy is to increase the often prohib­i­tively low print­ing speed.

A leading approach is the solid­i­fi­ca­tion of a liquid ink by illumi­na­tion with intense laser beam pulses, using two-photon absorp­tion. Conven­tion­ally, a laser spot is scanned along the desired struc­ture, assem­bling it sequen­tially from a large number of voxels, which are 3D volume elements in analogy to 2D pixels.

Holographic laser print­ing aims to increase print­ing rate drasti­cally by illumi­nat­ing a large volume, consist­ing of millions of voxels, in a single exposure. To this end, a carefully designed phase mask is used to shape the laser beam into a 3D hologram that resem­bles the desired struc­ture. The required laser inten­sity is provided by an ultra-short laser pulse that appears spatially like a disk. As this “laser disk” propa­gates through the ink, the object is illumi­nated layer by layer, at the speed of light. These regions polymerise and form the final solid object, the other parts remain liquid and can be washed out.

In this project, the described print­ing technique shall be applied for complex 3D struc­tures and the utility of differ­ent imple­men­ta­tions of phase masks, such as diffrac­tive optical elements, spatial-light-modula­tors and optical metasur­faces, is investigated.