Problem
We want to transmit a 200 MHz bandwidth digital signal over an optical
ps
system. The applied multimode fiber's chromatic dispersion is D c =5
, the
nm  km
specific modal dispersion bandwidth is b m =2 GHz  km , while the fiber's attenuation
is 1.2 dB/km. The transmitter's chromatic bandwidth is 5 nm, the power launched
into the fiber is 10 mW. The cable is available in 2 km factory length. The average
attenuation of the applied splicing technology is 0.2 dB, while the fiber connecto rs'
attenuation at the optical terminals are 1.5 dB each.
Q.1. What is the dispersion limited connection length.
Problem There is a multimode optical fiber connection. The chromatic dispersion
coefficient and the specific modal dispersion bandwidth of the applied fiber are
ps
D c =5
and b m =500 MHz  km respectively, while the transmitter’s LED
nm  km
spectral width is 25nm. If the connection’s length is doubled the optical bandwidth is
getting 1.5 times smaller.
Q. What is the original length and bandwidth of the connection?
Problem The optical bandwidth of a 10 km long multimode optical fiber connection
is 800 MHz. The fiber’s  coefficient is 0.5.
Q.1. Give an upper and lower bound for the optical bandwidth of a 40 km connection
made of same elements.
Q.2. What is the length of a 500 MHz connection, if, in addition to the 10 km one,
we also know the bandwidth of a 40 km connection, which is 300 MHz?