A Hybrid Fiber-Solid-State Laser with 3D-Printed Intracavity Lenses

We report on a miniaturized laser system that combines a bulk Nd:YVO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> crystal with fiber-guided optics in a hybrid device by implementation of on-fiber 3D-printed microlenses. These lenses, fabricated by direct laser writing onto no-core fibers, focus both the pump and the signal beams on the laser crystal. This reduces the footprint down to only 5 cm × 5 cm for the free-space section. The overall setup and images of the lenses are shown in Fig. 1. Pump light input and laser light output are fully fiber-coupled. We achieve stable continuous-wave lasing at over 20 mW output power at 1063.4 nm, with minimal (0.3% rms) intensity fluctuation over one hour. The system reaches a maximum of 37mW output when pumped at over 2 W, only limited by the off-the-shelf fiber Bragg grating.