Optical energy delivery apparatus for ablation or embolization includes an optical fibre having a distal end which is provided a light directing element, such as a lens. The light directing element is configured to direct optical energy beyond the distal end of the optical fibre. The optical fibre includes at least one Bragg grating proximate the distal end for sensing a change in the optical fibre during its operation. The apparatus includes a control unit configured to drive an optical source and to obtain signals from a sensor unit. The controller may also drive the energy source at a sensing wavelength. The structure provides a single optical fibre supply optical energy and sense changes in optical fibre. The optical fibre may have a tapering diameter towards its distal tip for increased flexibility at its distal end.
