Nanostructuring

• Two-photon polymerization (2PP) technique
• Characterisation of Laser Process Emissions
• Nonlinear Maskless Lithography
• Laser-Based Nanoparticle Generation
• EUV-Metrology

How small are the smallest structures that can be marked or processed using a laser? That is the vital question, for example for lithography mask repair, or the investigation of biological phenomena in individual cells. It rapidly becomes obvious that structures of a few nanometers (one billionth part of a meter) can only be generated using different non-linear optical techniques, such as ultrashort laser pulses.

Using ultrashort laser pulses, material ablation is only possible when a sharply defined intensity threshold is exceeded. If the pulse energy is adjusted so that the threshold is only exceeded at one point, grooves of only 200 nm thickness can be cut.

A second method is to guide the laser radiation through a tiny fiber end with a diameter of only 100 or 200 nm, which is located directly at the workpiece. Here, by analogy with a scanning nearfield optical microscope (SNOM), the fiber end serves as a type of ‘funnel’ for the light.

For biological investigations in this order of magnitude, the LZH has built ‘optical tweezers’. Using these tweezers, micrometer-sized, transparent spheres or living cells and organelles can be captured without contact, and moved in three dimensions. Thus, on the one hand they can be examined under the microscope with high resolution, and on the other hand they can be processed without affecting their vital functions.