A fiber of 1 km length has Pin=
1 mW and Pout = 0.125 mW. Find the loss in dB/km.
A communication system uses 8 km of fiber that
has a 0.8-dB/km loss characteristic. Find the output power if the input power is 20 mW.
A 5-km fiber optic system has an input power
of 1 mW and a loss characteristic of 1.5 dB/km. Determine the output power.
What is the maximum core diameter for a fiber
to operate in single mode at a wavelength of 1310 nm if the N.A. is 0.12?
A 1-km-length multimode fiber has a modal dispersion
of 0.50 ns/km and a chromatic dispersion of 50 ps/km · nm. If it is used with an LED with a linewidth
of 30 nm, (a) what is the total dispersion? (b) Calculate the bandwidth (BW)
of the fiber.
A digital MUX operates with 16 sources. The rate
of data in each source is 8000 bytes/sec (assume 8 bits per byte). Data are transmitted byte by byte.
What is the data
rate of the MUX output?
What is the channel switching rate?
A receiver has a sensitivity Ps of
–40 dBm for a BER of 10–9. What is the minimum power (in watts) that must be incident on the detector?
A system has the following characteristics:
LED power (PL)
= 1 mW (0 dBm)
LED to fiber
loss (Lsf)= 3 dB
Fiber loss per
km (FL) = 0.2 dB/km
Fiber length
(L) = 100 km
Connector loss
(Lconn) = 3 dB (3 connectors spaced 25 km apart with 1 dB
of loss each)
Fiber to detector
loss (Lfd)= 1 dB
Receiver sensitivity
(Ps) = -40 dBm
Find the loss margin and sketch the power budget
curve.
A 5-km fiber with a BW ´ length product of 1200 MHz ´ km (optical bandwidth) is used in a communication
system. The rise times of the other components are ttc = 5 ns, tL = 1 ns, tph = 1.5 ns, and trc
= 5 ns. Calculate the electrical BW for the system.
A 4 ´
4 star coupler is used in a fiber optic system to connect the signal from one computer to four terminals. If the power at an input fiber to the star coupler is 1 mW, find (a) the power at each output fiber and (b) the power division in decibels.
An 8 ´
8 star coupler is used to distribute the +3 dBm power of a laser diode to 8 fibers.
The excess loss (Lossex) of the coupler is 1 dB. Find the
power at each output fiber in dBm and mW.
