EE466 Optical Engineering
Homework #4
1.
(Book problem 9.21)
A stepindex fiber has radius a=5
μ
m, core refractive index
n
1
=1.45, and fractional refractiveindex change
Δ
=0.002. Determine the shortest
wavelength
λ
c
, for which the fiber is a single–mode waveguide.
If the wavelength is
changed to
λ
c
/2. Identify the indexes (l,m) of all the guided modes.
2.
(Book problem 9.33) At
λ
o
=820 nm the absorption loss of a fiber is 0.25 dB/km and
the scattering loss is 2.25 dB/km.
If the fiber is used instead at
λ
o
=600 nm, and the
calorimetric measurements of the heat generated by light absorption give a loss of 2
dB/km, estimate the total attenuation at
λ
o
= 600nm.
3.
(Book problem 9.34) Determine the core radius of a multimode stepindex fiber with
a numerical aperture NA=0.1 if the number of modes M=5000 when the wavelength
is 0.87 mm.
If the core refractive index n
1
=1.445, the group index N
1
=1.456, and
Δ
is
approximately independent of wavelength, determine the modaldispersion response
time
σ
τ
for a 2 km long fiber.
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 Spring '11
 kasab
 single mode, data rate, class web site

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