Assignment 2:
Important Notes:
1) Only assignments answered in assignment form will be accepted.
2) Due date for handing in Assignment2 is Monday 10/12/2012.
Handing in the assignment: locker 15, 3rd floor.
The German University in Cairo
Faculty of Information Engineering & Technology
Electronics Department
Electronics and Communications 9
Photonics (Elct 901)
Fall 2012
th
semester
Assignment 2
Problem 1:
Without optical amplification it is not possible to optically transmit data from London to
NewYork, i.e. 7000 km of fiber length with an attenuation of 0.2 dB/km. Therefore Erbium
doped fiber amplifiers (EDFA), which can amplify an optical input signal of -15 dBm to +1
dBm, are employed for a transatlantic fiber link. Assume that the optical transmitter at
London is sending with an optical power of +1 dBm and that the receiver at New York is able
to detect optical signals down to -35 dBm. How many EDFA are necessary for a working
optical transatlantic fiber link?
Problem 2:
Describe briefly the principle of operation of a Raman amplifier. Explain in words at what
wavelengths can signals be amplified.
Problem 3:
Quartz is a positive uniaxial crystal with ne = 1.553 and no = 1.544. (a) Determine the
retardation at λ0 = 633 nm when the crystal is oriented such that retardation is maximized. (b)
At what thickness does the crystal act as a quarter‐wave retarder?