[開課學院]: 資電學院
[開課系所]: 電機系
[課程名稱]: 光纖工程
[老師名稱]: 申浩然 老師
[開課學期]: 98-2
[類型]: 98-2期末考
1. Follow the questions with one correct answer: (50%)
(1)At what wavelength dose PMMA plastic fiber have the lowest loss?
a. 500nm
b. 650nm
c. 850nm
d. 1.3μm
e. 1.55μm
(2)How does increasing the refractive index of the core of a fiber make it
better for coupling light into fiber?
a. It reduces attenuation of the glass.
b. It increases NA and reduces attenuation of the glass.
c. It increases NA and reduces bend sensitivity.
d. It decreases NA, bend sensitivity, and reduces attenuation.
e. It reduces bend sensitivity and glass attenuation
(3)What wavelengths are amplified by an erbium-doped fiber amplifier?
a. 980-1480nm
b. 1250-1350nm
c. 1300-1700nm
d. 1470-1530nm
e. 1530-1620nm
(4)What creates the grating effects in a fiber grating?
a. lines etched on fiber surface by high-power ultraviolet pulses
b. changes in the refractive index of the fiber core induces by
ultraviolet light
c. interference among several modes in a multimode fiber
d. variations in glass composition caused by changes in doping during
perform fabrication
e. optical white magic
(5)A single-mode fiber has material dispersion of 20ps/nm-km and
waveguide dispersion of -15ps/nm-km at the signal wavelength.
What is the total chromatic dispersion?
a. 35ps/nm-km
b. 25ps/nm-km
c. 5ps/nm-km
d. 0ps/nm-km
e. -35ps/nm-km
(6)A 1-m length of fiber transmits 99.9% of the lightentering it.
How much light will remain after 10km of fiber?
a. 90%
b. 10%
c. 1%
d. 0.1%
e. 0.0045%
(7)You transmit an instentaneous pulse through a 20-km multimode fiber
with total dispersion of 10ns/km at the signal wavelength. What will
the pulse length be at the end?
a. 200ns
b. 100ns
c. 50ns
d. 20ns
e. 10ns
(8)You transmit an instantaneous pulse through a 20-km single-mode fiber
with chromatic dispersion of 10ns/km at the signal wavelength. The
spectral width of the input pulse is 2nm. What is the pulse length
at the end of the fiber?
a. 400ns
b. 250ns
c. 200ns
d. 100ns
e. 32ns
(9)What impurity levels are required in fused silica for communication
fibers?
a. less than 0.1%
b. less than 0.001%
c. one part per million
d. ten parts per billion
e. one part per billion
(10)What type of fiber could transmit the highest laser power?
a. step-index silica fiber with a 550-m core
b. hard-clad silica fiber with a 100-m core
c. all-plastic fiber with a 1000-m core
d. single-mode fiber
e. plastic-clad silica fiber with a 200-m core
2. Please state four causes to attenuate the light power transmitted
in an optical fiber? (8%)
3. Please state five types of nonlinear effects in optical fibers? (10%)
4. Please state four types of dispersions along the length of fibers? (12%)
5. (a)What is chirped fiber grating? (5%)
(b)Why a chirped fiber grating can be used for dispersion
compensation in optical fiber communication system? (5%)
6. We are using nonzero dispersion-shifted transmission fiber with
dispersion of +8ps/nm-km at 1530nm for optical communication system.
Suppose we want to have total chromatic dispersion of +2ps/nm-km at
1530nm over a 1200-km system. How to arrange the lengtha of
transmission fiber and the dispersion-compensating fiber with
dispersion of -100ps/nm-km at 1530nm? (10%)
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※ 編輯: R16 來自: 122.117.10.204 (07/03 01:40)