High resolution optical time-domain reflectometry using sub-picosecond laser sources

The operation of optical fiber sensors using optical time-domain reflectometers (OTDRs) is outlined. Limitations introduced by telecommunication OTDRs used in these sensors are discussed. Other approaches based on specialized short-range OTDRs are presented. Finally, OTDRs based on sub-picosecond fiber laser sources and fast detection and acquisition systems.