M.Sc. (Semester II) (CBCS) Examination Nov/Dec-2018
Electronics
OPTO ELECTRONICS
Time: 2½ hrs Max. Marks: 70
Instructions: Attempt five questions.
Q. 1 and 2 are compulsory.
Answer any three questions from Q.3 to Q.7
Figures to the right indicate full marks.
Q.1 Choose correct answer. 08
Numerical aperture
n1 2Δ 1/2 sin θa
n1-n2/n1 both a and b
In optical fibers dispersion means pulse
narrowing broadening
rise time none of these
The circular active area in practical surface emitter is normally
in diameter.
25 2.5
50 45
Optical fiber communication uses spectral band.
Visible far IR
Ultraviolet None of these
In P-N photodiode of depletion region depends on doping
concentration.
Length Height
Width Length and width
is maximum difference between refractive indices exhibited by
the material.
Birefringence Pockel's effect
Intensity modulation None of these
Which of following material exhibits quadratic electro-optic effect?
Crystalline silica Non-centro symmetric
Centro symmetric All of these
are generally permanent fiber joints.
Splices Couplers
Connectors None of these
State True or false. 06
LASER stands for light amplification simultaneous emission of
radiations.
A typical glass fiber is about 100 to 125 in diameter.
In single mode step index fiber RI of the core is same throughout.
Optically isotropic materials are called birefringent.
Pockel's cell works with the non linear effect.
For glass fabrication silicon dioxide is basic material.
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Q.2 Answer any two of the following: 10
Write a note on Acceptance angle.
State the difference between LASER device and simple LED.
Write a note on optical anisotropy.
What is direct intensity modulation? 04
Q.3 Explain with neat diagram construction and working principle of Light
Emitting Diode.
08
Explain the different loss mechanisms. 06
Q.4 Explain the principle of Birefrigence in uniaxial crystal with necessary
diagram.
08
What are the three kinds of polarization? 06
Q.5 Explain in detail the optical fiber fabrication processes. Describe the
characteristics of the materials used for fabrication of optical fibers.
08
Write a note on couples. 06
Q.6 Describe in detail Pockel's and Kerr's effect for light modulation. 08
Write a note on pulse spread due to material dispersion. 06
Q.7 Define optical fiber communication. Explain construction and working
principle of optical fiber.
08
Write a note on Faraday's effect. 06