L-BAND LIGHT SOURCE FOR OPTICAL ELEMENT MEASUREMENT USING FEEDBACK LOOP

摘要

PROBLEM TO BE SOLVED: To obtain an L-band light source with high intensity and small difference in optical output according to the wavelength by allowing seed beam to be incident or a rare-earth-added optical fiber and into a feedback loop, and by incorporating forward-direction optical isolators which blocks backflow. SOLUTION: A seed beam refers to ASA which in generated when the input light passes through an erbium-added optical fiber. An EDF 203 is used as a light amplifying medium, and optical isolators 200 and 26 are inserted respectively in the front and rear ends, which sandwich the EDF 203 and prevent backflow of light. Pumped light emitted by pumping laser diodes 207 and 208 is emitted into the EDF 203. A feedback loop to produce seed beam in cludes a filter 210 which can select a specific wavelength of ASE and a forward- direction optical isolator 209 or a reverse-direction optical isolator which prevent backflow of the beam to be fed back.