Optical Time Domain Reflectometer with a Laser Diode Operating as Light Emitter/Photodetector

Abstract
A new optical time domain reflectometer is proposed that uses a semiconductor laser diode (LD) as a pulse emitter and a photodetector. By employing LDs with center wavelengths of 1.31 and 1.56 µm, fault location lengths longer than 10 km were attained in both wavelengths for a graded-index multimode fiber.