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APJ ABDUL KALAM TECHNOLOGICAL तारी
FIRST SEMESTER M TECH DEGREE EXAMNATION, DECEMBER 2018

Branch:Electronics and Communicarion

Stream(s):

1) Microwave and TV Engineering 2)
Telecommunication Engineering
Course Code & Name:

01806211 :Optical Communication Systems

Answer any Dvofull questions from each part
Limit answers to the required points.

Max. Marks: 60 Duration: 3 hours
PART A

1. 2. Whatare different dispersive effects and their causes in single mode fibers. 5 Graphically
demonstrate the zero dispersion condition.

४. A step index fiber has a core diameter of 8gm and a core refractive index of 4 1.48.
Find the numerical aperture of the fiber and estimate the shortest wavelength of light
which allows single mode operation when the relaHve refractive index difference for
the fiber is 1 %.

2. a. Explain the light generation technique in semiconductors. With necessary 6 diagrams
explain the structure of a hetro juncHon LED.

४. A hetrojunction InGaAsP LED emitting at peak wavelength of 860nm has 3 radiative
and non radiative recombination times of 2515 and 755 respectively. If the drive
current is 25mA find the internal quantum efficiency and internal power level.

3. 4. An InGaAs PIN diode having quantum efficiency 90%, dark current 4nA 9 operating at
a wavelength of 1300n_m with a transmission rate of 40Mbps subjected to incident optical
power of 300nW . The load resistance is 1K and negligible surface leakage current-
Calculate the photo current generated, the mean square values of noise components and
SNR.