Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 53: Quantum Optics and Photonics III

Q 53.4: Talk

Thursday, March 8, 2018, 11:15–11:30, K 0.016

Aberration compensation by complex beam shaping in direct laser writing implementing a SLM — •Mathias Hünecke, Haissam Hanafi, Jörg Imbrock, and Cornelia Denz — University of Münster, Institute of Applied Physics and Center for Nonlinear Science (CeNoS), Corrensstraße 2-4, 48149 Münster, Germany

Direct laser writing (DLW) is a powerful technique for creating complex refractive index structures in transparent materials. This technique paved the way to fabricate discrete waveguide arrays that allow tailored linear and nonlinear light propagation. Further applications of DLW are, for instance, diffractive optical elements or, in a visionary way, integrated optoelectronic devices.

The desired circular profile of waveguides is limited by spherical aberration and axial elongation caused by a refractive index mismatch when focusing from air into a high refracting material. These effects increase with larger writing depth, higher refractive index mismatches and higher numerical apertures. To overcome these limitations and enhance both, the variety of accessible materials and the writing depths, we apply complex beam shaping methods.

We will present an adaptive compensation of these aberrations by a spatial light modulator (SLM), which we implemented in a conventional DLW system. By applying a specific phase hologram, the initial wavefront is modified and reaches a spherical focus inside the writing volume. We demonstrate adaptive aberration correction in fused silica and nonlinear optical lithium niobate and characterize its performance for different parameters such as writing depth and numerical aperture.