High-spatial-resolution and high-sensitivity interferometric optical-time-domain reflectometer

An interferometric optical-time-domain reflectometer is presented. The system is a low- coherence interferometer using a superluminescent diode and has a spatial resolution of 20 micrometers . A high-sensitivity system is described which performs balanced and narrow band detections and has a detectable limit of -130 dB, which is 10 dB lower than the Rayleigh scattered light power in optical fibers. A polarization-independent system is proposed which adopts polarization-diversity detection to suppress the influence of the polarization fluctuation of the scattered light. A CO 2 laser probing method is applied using the thermo- optic effect to identify scattering centers in optical circuits. Measurement of fault locations, reflectivity, and characterization of optical components with the systems are also described.