An optical fiber for use with a laser device including a source of light energy, as well as a method of making such optical fiber, where the optical fiber has a proximal end in communication with the light source and a diffuser portion positionable at a treatment site. The optical fiber includes: a core having a proximal portion, a distal portion and a distal face proximate the diffuser portion of the optical fiber; a layer of cladding radially surrounding the core from the core proximal portion to a point adjacent the core distal portion; a layer of optical coupling material radially surrounding at least a portion of the core distal portion; a slug including a light-scattering material therein positioned adjacent the distal face of the core and a distal end of the optical coupling layer, wherein the light-scattering material fluoresces in a temperature dependent manner upon being stimulated by light; and, a sleeve radially surrounding the cladding layer, the optical coupling layer and the slug, wherein the sleeve is composed essentially of a predetermined type of material; wherein the light-scattering material of the slug is molded with substantially the same type of material utilized for the sleeve.
