Resolution controllable optical time domain reflectometry based onlow coherence interference

A low-coherence optical time domain reflectometer (OTDR) that can control spatial resolution is proposed to efficiently diagnose waveguides. This is achieved using a light source consisting of a superluminescent diode (SLD), an optical bandpass filter for truncating the SLD output, and an antireflection-coated laser diode booster amplifier. Two resolutions, 44 and 14 μm, were experimentally demonstrated with and without the filter having a 2.7-nm full width at half maximum (FWHM), respectively. The length of the blind space and the minimum detectable reflectivity were respectively <7 mm and <-134 dB at a 3-Hz detection bandwidth, for both resolutions. The noise characteristics of the light source and the system performance are investigated theoretically and experimentally