Question

A fiber manufacturer specifies a PMD coefficient of 0.05 ps km-1/2. (a) What is the average Differential Group Delay, DGD, after transmission through 200 Km of this fiber. (b) What is the average pulse spread after transmission through 200 Km of this fiber. (c) What is the estimate for maximum Bitrate of data that can be transmitted through this fiber if the only dispersion mechanism was PMD? (c) What is the bit period for 10 Gb/s of data? (d) If we want to transmit 10Gb/s of data, how long can the fiber be?

Answer 1

Consider the PMD coefficient as, PMDoff = 0.05 ps//km. (a) The average differential group delay (DGD) is PMD (Polarization Mode Dispersion) whose symbol is Ar Write the expression for average differential group delay Ar PMD 'coeff Here, L is the fiber length Substitute 200 km for L and 0.05 ps/Vkm for PMDcoff Ar = (0.05 ps/Vkm),/200 km =14.142 0.7071 ps Therefore, the average differential group delay (DGD), Ar is 0.7071 ps (b) Write the expression for average pulse spread. - L(PMD) Ao Here AT 1 Δω- Δτ 1 0.7071 -1 =1.414 ps Calculate the average pulse spread AT (200) (0.05) (1.414) ps 0.707 ps Therefore, the pulse spread is 0.707 ps

(c) Write the expression for the maximum Bitrate with only dispersion mechanism is PMD 1 Brmax 2AT 1 2(0.7071x 10-12) 0.7071x101 = 70.71 Gbit/s (d) 1 Bit Period _ Bit rate 1 10 x10 0.1 ps Therefore, the bit period is |0.1ps