Innovative implementation of the phase-shift method for field measurement of chromatic dispersion

Abstract

A new implementation of the modulation phase-shift technique is presented that is well adapted for field use. The method uses measurements of modulation amplitudes to compute relative group delays (RGD). Unlike existing phase-shaftmethod implementations, this technique requires no control or calibration of relative phases in the electrical domain. For RGD measurements, a broadband LED emitter -tunable filter receiver combination is used. With this simple set-up, ten RGD measurements taken at 16 different wavelength points (i.e. over 160 measurements) gave standard deviations of 2 to 6 ps for 100 km of standard fiber. Standard fiber (non-zero dispersion shifted) lengths of over 160 km are accurately measured.