Optical fiber length measurement by external phase modulation type optical heterodyne reflectometry

A method for measuring optical fiber length is proposed and demonstrated experimentally with external phase modulation optical heterodyne reflectometry using a He-Ne laser as a light source. The system offers a simple length-measuring method with satisfactory resolution. The reflected waves from fiber faults, if any, also can be detected by this method by observing two signals which occur at fault points and fiber end.<
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