Ring-in-ring beam shaping based on a 3D nanoprinted microlens on fiber tip

Micro-optical elements have been attracting growing attentions in various applications, such as telecommunication, sensing technology and laser industry. In this paper, we propose a 3D printed freeform microlenses on fiber tip for spatial beam intensity shaping. Femtosecond laser two-photon polymerization (TPP) technic is used for fabrication of the microlens. Both simulation and experiment results have demonstrated that the Gaussian beam output from a single-mode fiber can be successfully transferred to a ring-in-ring beam by using the fiber-tip microlens. The study indicates that TPP is a powerful tool for the integration of micro-scaled beam shaping elements on optical fibers.