A method of optical time-domain reflectrometry in optical fiber is described that uses a single distributed feedback diode laser and a reference reflector. When the period of the frequency modulation of the laser matches the time difference between the reference reflection and the reflection of interest an increase in the noise at the detector occurs. The locations of reflections within the fiber are then mapped to frequencies at which the noise at the detector increases. A sinusoidal frequency modulation is analyzed, and an experiment is described in which the system is used to measure the location and the wavelength of two Bragg gratings located 10 cm apart in an optical fiber. Wavelength measurement is accomplished by temperature tuning the diode laser.
© 1998 Optical Society of America
(060.2310) Fiber optics and optical communications : Fiber optics
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(060.2400) Fiber optics and optical communications : Fiber properties
(060.2630) Fiber optics and optical communications : Frequency modulation
Mark Froggatt and Willie Bowen, "Optical Time-Domain Reflectometry in Optical Fiber With Reflection Delay Time Matched to the Period of the Optical Frequency Modulation," Appl. Opt. 37, 1731-1734 (1998)