Experimental method for the separation of material and modal dispersion of optical fibres

Time-domain pulse distortion measurements with a pulsed 0.85- mu m (GaAl)As laser diode and a grating spectrometer as spectral-halfwidth filter were used to separate experimentally the total pulse dispersion of a graded-index fibre into parts of material and modal dispersion. Cabled SIECOR graded-index fibres show a material dispersion coefficient of (107+or-4) ps/km.nm and a modal dispersion of 200 ps to 300 ps after 1.574 km fibre length, both at lambda =851 nm.