Method for end-face treatment of specialty optical fiber with thick-walled silica glass tubes

A “cleaving-polishing” process for end-face treatment of specialty fiber supported by thick-walled silica glass tubes is proposed. The fiber tension is determined by the fiber fracture theory for improved cleaving. This method overcomes polishing problems caused by steel or ceramic ferrules. Approximately 20 min on average is required for polishing a specialty fiber end face with a sampling roughness of 7.42 nm, confirmed by microscopy ($400\times$) and interferometry. A comparison of laser coupling efficiencies between fibers with cleaved ends and fibers with polished ends showed that the coupling efficiency of the former could be enhanced by 15% through polishing.