an improved optical fiber comprising a waveguide with an input for coupling focused laser energy into the waveguide and communicating electromagnetic radiation in a propagation direction to an internally reflective tip of the waveguide , a tissue contacting surface wherein the light path from the reflecting surface to the transmitting surface in substantially homogenous in refractive index and cooled by fluid flow . in minimizing the variations in refractive index within the lateral light path , while providing active cooling directly below the tissue contact surface , the invention prevents internal reflections and beam distortion and greatly improves the efficiency and durability of the laterally directing probe . free rotation of the tissue contact surface , about the lateral tip , may be provided and tissue vaporization efficiency may be improved by providing a morcellating tool on the tissue contact surface .