Multidirectional Illuminating Optical Fiber Tip on Beam Expanding Coreless Silica Fiber

We report a compact all-optical side-firing probe directly ablated on a mode-expanded hybrid fiber end using a high-precision femtosecond laser processing technique. A segment of coreless silica fiber was adopted to achieve a large beam size and manipulation of the far field divergence angle. The radiating beam properties of the side-firing tip have been experimentally investigated and compared with numerical simulations.