Photonic crystal fibers and medical systems including photonic crystal fibers

2 In general, in one aspect, the disclosure features a system that includes a flexible waveguide having a hollow core extending along a waveguide axis and a region surrounding the core, the region being configured to guide radiation from the COlaser along the waveguide axis from an input end to an output end of the waveguide. The system also includes a handpiece attached to the waveguide, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient and the handpiece includes a tip extending past the output end that provides a minimum standoff distance between the output end and the target location.