Measurement of chromatic dispersion in optical fibers using pairs of correlated photons

Photon pairs generated by spontaneous parametric downconversion are used to implement a novel technique for measuring the chromatic dispersion of optical fibers. The time and energy correlation of the photons of a pair allow a measurement with a high time resolution which is only limited by the detection electronics. The device gives direct access to the differential group delays at several wavelengths around 1.3 mu m Our prototype setup is capable of measuring group delay differences with a resolution of about 5 ps, only limited by the upper delay limit of the time interval analyzer (presently 50 ns). (C) 1998 Elsevier Science B.V. All rights reserved.