Measurements of Intermodal Dispersion In Graded Index Optical Fiber
Dr.Mohamed Saleh Ahmed , Layale Yahya Salih

Dr. Mohamed Saleh Ahmed , Jassim Kadim Hmood , Abdulla Ali Kassim Abstract The aim of this research is to examine experimentally the laser pulse transmittance in graded index optical fiber. However attention is paid on the evaluation of intermodal dispersion. Four signals (λ=680nm and power= 0.1mW) of different frequencies (138.889, 277.778, 645.16, and 1369.863 Hz), of pulse widths (7.2, 3.6, 1.55, and 0.73 ms) respectively are sent through a 400m multimode graded index fiber. A p-i-n detector is used to receive output signals. Intermodal dispersion has been noticed and the pulse width broadening for each frequency is recorded. They are (7.22, 3.61, 1.555, and 0.732 ms) that lead to frequencies of (138.504, 277.008, 643.08, 1366.120 Hz) respectively. That change in frequency has to be taken into account whenever fiber optic dependence communication, guidance, or control systems are considered.