Miniature 120-beam coherent combiner with 3D-printed optics for multicore fiber-based endoscopy.

In this Letter, we report a high-efficiency, miniaturized, ultra-fast coherent beam, combined with 3D-printed micro-optics directly on the tip of a multicore fiber bundle. The highly compact device footprint (180 µm in diameter) facilitates its incorporation into a minimally invasive ultra-thin nonlinear endoscope to perform two-photon imaging.