An instrument for measuring chromatic dispersion in optical fibers. The instrument
comprises two independent modules, an optical source (2) and a receiver
(4). The optical source (2) comprises two pulse producing
circuits: one driving a laser (35), which will be used as a timing reference,
and the second driving a light emitting diode (LED)(34), emitting a short
light pulse with a broad spectrum. The receiver (4) comprises a
wavelength-selection element (46), which filters one or several wavelengths
out of the LED spectrum, a photodetector (43) for detection of the laser
pulse, a photon-counting detector (41) for detection of the filtered LED
pulses, and a high-resolution timing circuit (42) for measuring the time
delay between the laser pulse and the LED pulse. A preferred embodiment includes
the wavelength-selection element (46) which is a series of Bragg gratings,
thus selecting several fixed wavelengths.
