Chromatic Dispersion Measurements in Single-Mode Fibers Using Picosecond InGaAsP Injection Lasers in the 1.2- to 1.5-um Spectral Region

Modal and chromatic dispersion measurements in multimode and single-mode fibers provide important information about the bandwidth limitations in optical fiber transmission. A near-infrared, fiber Raman laser with subnanosecond pulses in the 1- to 1.7-/im region can be used for dispersion measurement in both multimode and single-mode fibers.1"3 While this infrared-fiber, Raman-laser-based measurement system has been very useful and widely adopted, it has its limitations in terms of time resolution (by the mode-locked laser pulsewidth, ~140 ps) and is not suitable for field measurements because of its large size. In this paper we describe a simpler dispersion measurement system based on picosecond InGaAsP injection lasers and ultrafast InGaAs p-i-n detectors. This is similar to the measurement system we used for measuring high-bandwidth multimode fibers,4 except now in order to study the chromatic dispersion in single-mode fibers by pulse delay measurements, we need to use injection lasers at different wavelengths in the 1.3-/xm spectral region. Besides being more compact, this system also has a better time resolution than the fiber Raman laser setup. 457