The subpicosecond OTDR has been investigated as a diagnostic tool for the fiber optics components and integrated waveguide devices. The mode-locked dye laser at 1.3 μm was excited by Nd-YAG compressed pulses. 300 fsec pulses have been generated at the rate of 82 MHz. Using correlation detection a spatial resolution of ~60 μm in air and ~20 μm in GaAs was achieved