Nano diffractive optics. Nano structured Fresnel axicon lens for ultrahigh resolution optical coherence tomography (OCT) and large size, high efficiency gratings for ultrafast chirped pulse amplified lasers

Abstract

We aim to develop novel nano-scale diffractive optics. To reach this goal, we will make an accurate design using a modeling tool, and we will employ innovative production techniques in order to reliably produce the components. One diffractive optic component is, to the best of our knowledge, not available and will bring a breakthrough in optical imaging and other applications: the Fresnel lens concept applied to the axicon lens – the fraxicon lens. This is the critical component to generate 1-micron narrow Bessel beam, which is currently limited by the large radius of the mechanically produced conical tip in the glass substrate. We will explore the use of Direct Laser Writing (DLW) lithography to produce fraxicons with sub-micron rounded tip and implement those superior fraxicons in an ultrahigh-resolution Optical Coherence Tomography 3D imaging system. Furthermore, we will explore methods for producing very challenging optical gratings. We first intend to design and produce high efficiency IR gratings with large number of lines per mm and very large physical size using DLW lithography, Moreover, we aim to design and produce deep-UV (260 nm) gratings with very large number of lines per mm (3846 l/mm) in a large size (>30x30 mm) by means of e-beam and nanoimprint lithography. These kinds of gratings are the key components for femtosecond chirped pulse amplified laser systems. We will characterize and implement those superior gratings in femtosecond laser amplifiers at FHNW and at PSI.