Side-emitting optical fibers for lasers

There is provided a side-emitting optical fiber having a proximal end for receiving radiation and a distal end for emitting the radiation in a direction laterally of the longitudinal axis of the fiber via a radiation exit region at the distal end; characterized in that the outer surface of the distal end of the a glass cap is formed with a visually discernible surface formation which is narrow at one end thereof and which increases in width towards the opposite end thereof, to thereby enable visually discerning the orientation of the optical fiber with respect to the radiation exit region thereof.