Recent progress in research on fiber devices using special fibers by CO2 laser irradiation technique

Recent progress in research on fiber devices using special fibers by CO₂ laser irradiation technique are reviewed. Especially, their newly and precisely controlled characteristics are presented. For the lowest insertion loss and simplest implementation devices, which are effective for access networks, an all-fiber solution is preferred. By the way, numerous optical fiber devices, such as optical couplers and optical filters, have been proposed and used for optical transmissions. Their fiber devices have produced by various fiber processing techniques. While, the techniques which are clean and control the device characteristics after main fiber processing have not been yet developed.