Optical fibers for delivering laser energy inside the body are often tasked with traversing tortuous routes in accessing the target tissue or pathology, e.g. ureteroscopic laser lithotripsy. A common failure in such applications, known in the field as ‘fiber burn through’, has been known to injure patients and is a major cause of damage to ureteroscopes. Where irregular output that is produced at the start of a lasing interval passes through a fiber that is at or near the optical minimum bend limit, fail safe polymer claddings are damaged and can no longer contain even regular laser output in tight deflection. The invention disclosed provides a solution to premature fiber failure and collateral damage.