FEMTOLITHO · Ultrahigh resolution femtosecond laser lithography for applications in life sciences and display technologies

Femtosecond laser fabrication by nonlinear laser lithography is a powerful method for the fabrication of high resolution, 3D structures. This laser fabrication method allows the creation of 3D structures with sub-diffraction limit resolution, an impossible task for traditional lithographic techniques. In femtosecond laser lithography, starting liquid photoresists are converted into solid phase upon exposure to femtosecond laser light. Standard femtosecond laser lithography enables submicrometer resolution but in many applications it is desirable to achieve even finer resolutions. Applications such as photonic crystals for visible wavelength biosensors, optical-wavelength metamaterials showing negative refraction both require sub 100-nm resolution. Such resolution requirements are not achievable with traditional femtosecond laser fabrication techniques. As the main objective, we will study two different strategies to deplete two photon absorption in the outer region of the laser-material interaction volume to greatly improve the resolution of femtosecond laser lithography. First, we will adapt a method based on stimulated emission depletion, which has shown resolutions of less than 10 nm in microscopy. Secondly, we will seek to optimize quencher diffusion to enhance the resolution possible by femtosecond laser lithography. We will apply these carefully tuned laser-material interactions to form ultrahigh resolution 3D microstructures to study their influence on two elements of crucial importance in life and in science and technology: stem cells and liquid crystal molecules.