3D-nanoprinted fiber-integrated microlenses enhanced with an aspherical surface for spot size minimization

Microoptics plays a pivotal role in photonics due to its significant potential for system miniaturization. Consequently, ongoing efforts aim to improve the performance and functionality of these components. Microlenses represent one of the key technologies under development and are already employed in applications such as sensing and beam-scaling systems. However, their performance can be further improved to broaden their applicability across more demanding scenarios. The optimization of complex microlens designs typically involves analytical or numerical tools, with a wide variety of such tools available. These tools often yield discrepancies between their results. In this work, we compare an analytical method with a numerical one and evaluate the performance of a microlens fabricated using a high-precision nanoscale 3D-printing technique, enabling the fabrication of complex surfaces. We optimized both spherical and aspherical surfaces in terms of their spot size - a parameter whose optimization is crucial for many applications, such as fiber-coupling setups.