Design of a long-range single-mode OTDR

The design of a high-performance single-mode optical time-domain reflectometer (OTDR) is discussed. The approach uses a low-noise receiver with a p-i-n diode detector and transimpedance amplifier together with multichannel digital averaging. A dynamic range of 30 dB one way at 1.3 μm is demonstrated with a laser diode source, and with a Nd:YAG laser source the dynamic range is 41 dB one way.