1. COMMUNICATION ENG. PROF. A.M.ALLAM
TUT3
FIBER COUPLERS&OPTICAL NETWORKS
LECTURES

2. COMMUNICATION ENG. PROF. A.M.ALLAM
1-A four port directional coupler has 4:1 splitting ratio and an excess loss
equal to 2 dB. The coupler’s directionality is 40 dB
(a) What fraction of the input power goes to each of the ports?
(b) Compute the throughput loss and tap loss
2-Consider an ideal tapered single-mode directional coupler having 1:1
splitting ratio. The coupling coefficient is Δβ = 1rad/mm
(a) What is the length of the coupling region?
(b) Repeat for a 10:1splitting ratio
LECTURES

3. COMMUNICATION ENG. PROF. A.M.ALLAM
3- A five terminal tee network is structured like the one shown in Fig. a. The tee
couplers are like the one shown in Fig. b. Assume ideal 3-dB couplers, ideal fibers,
and lossless connectors
(a) Draw the entire network
(b) Compute the transmission loss to each of the receivers when the terminal 1 is the
transmitter
Fig.a
Fig.b
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4. COMMUNICATION ENG. PROF. A.M.ALLAM
4-A star network in the figure connects five terminals. The excess loss of the star
coupler is 2 dB, connector losses are 0.8 dB, splice losses are 0.2 dB, and the fiber
loss is 35 dB/km. Terminal 1, 2, 3, and 4 are 100 m from the star coupler
Terminal 5 is 20 m from the star coupler
(a) Sketch the network (include all the connectors and the splices you think you need).
(b) If terminal 1 transmits, compute the total transmission loss (in decibels) to each of the receivers
LECTURES

5. COMMUNICATION ENG. PROF. A.M.ALLAM
(5) Sketch a four-channel, full-duplex WDM network. Choose specific
multiplexer / demultiplexer and directional coupler schemes, and clearly
draw the path taken by four different wavelengths
(6) An ideal tapered and fused single-mode coupler is used as a two-
wavelength demultiplexer with inputs at λ1 and λ2 at port 1. At
wavelength, λ1, the coupling coefficient has the value 2 rad/mm. This
wavelength is coupled entirely to port 3. Wavelength λ2 is transmitted
entirely to port 2.
(a) Compute the interaction length.
(b) Compute the value of the coupling coefficient at λ2.
(c) Compute the value of the coupling length at λ2.
(7)For a WDM system (i.e. system operates over the C-Band covering wavelengths from 1530nm – 1565m) with channel spacing of 25 GHz. Find the number of channels transmitted over this band and the total capacity of the system if each channel operates at 10 Gb/s.
LECTURES