Ultraviolet laser delivery using an uncoated hollow taper

We demonstrate a simple grazing-incidence-based method for ultraviolet (UV) laser delivery and direct laser-to-taper coupling using an uncoated glass hollow taper. The taper serves as a mode homogenizer that converts the strongly multimode distribution of the input laser emission into a high-quality smooth profile at the taper output. An uncoated pyrex-glass hollow taper is used for direct launching, without any intermediate focusing elements, of UV laser emission from the third harmonic ( 355 nm) of a Q-switched Nd:YAG laser into the taper. The linear hollow taper provides a laser-to-taper coupling efficiency exceeding 70%.