Measurement of propagation characteristics of an optical fiber is made by injecting a sequence of short optical pulses into the full length fiber and the short length (1.5m) fiber, and measuring by a sampling oscilloscope the temporal fiber response at the output with a fast optical detector (band width : 2.3 $GH_z$).
Time domain data is transformed to frequency domain by use of FFT algorithm, and the calculated results include baseband transfer function, baseband bandwidth (3 dB), impulse response, phase delay, and attenuation.
For the experiment, a subnanoseconds optical pulse generator (full width half maximum : 750ps), a triggering circuit and a variable delay generator for the trigger of the sampling oscilloscope are constructed.
