B.TechSemester 52025-26Optical CommunicationBEC057

Optical Communication (BEC057) - AKTU Question Paper 2025-26

B.Tech · Semester 5 · Free PDF Download

This is the official AKTU Optical Communication Previous Year Question Paper for B.Tech Semester 5, academic session 2025-26. Published by Dr. A.P.J. Abdul Kalam Technical University (AKTU/UPTU), Lucknow. Free PDF download — no login required.

Course:B.Tech

Semester:Semester 5

Session:2025-26

University:AKTU / UPTU

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Questions Asked in 2025-26

Optical Communication (BEC057) — complete question paper · 70 marks · 3 Hours

Section AAttempt all q u e s t i o n s i n b r i e f . 2 x 07 = 14

a
Define goos- haenchen shift in opt ical fiber waveguide
b
Explore why the Refractive Inde x (R.I.) of core and cladding are different. Which one has greater R.I. and why
c
What are the causes of attenua tion in optical communication? 2 K 2
d
Suppose a laser diode radiates red light with wavelength of 650 nm. Calculate the energy of a single photon?
e
What are advantages and disadva ntages of Avalanche Photodiodes
f
Define the term Photoluminescence
g
Define Coherent Detection

Section BAttempt any three o f t h e f o l l o w i n g : 07 x 3 = 21

a
What is the relationship between acceptance angle and refrac tive indices of core, cladding and medium for a light ray incident on fiber core? Calculate Numerical aperture of step index fiber having core refractive index of 1.57 and cladding refractive index as 1.40
b
Discuss various kinds of losse s that an optical signal might suffer while propagating through fiber, which i s most important one? What is the effect of these losses on light power and pulse shape?
c
Draw the structures of edge -emitting LED and surface emitting LED and explain the operation
d
Describe the different sourc e–fiber coupling techniques used in optical fiber communication systems. Compare LED–fiber and laser–fiber coupling methods
e
Write a short note on: 1.Free Space Optics (FSO) 2.Multiplexin
g
Transmission Techniques

Section CAttempt any one p a r t o f t h e f o l l o w i n g : 07 x 1 = 07

a
Draw and Explain the optical fiber communication system and Describe each component in detail
b
What do you mean by Numerical Aperture of an optical fiber? Derive an expression for Acceptance angle of optical fiber
a
What do you mean by mode coupling? Explain the various irreg ularities in the fiber of its causes
b
What is mean by dispersion? Des cribe the Intramodal dispersion
a
Define population inversion. Derive the threshold condition for laser oscillation to sustain
b
Discuss the LASER diode prin ciple , modes and threshold conditions
a
Describe the working principle of PIN photodiode with proper diagram
b
Explain the source-to-fiber power launching concept in optic al communication systems. Derive the expression for launched power considering geometrical and Fresnel losses
a
Explore Power Penalty in optical communication. Also Explain Different Types of Power Penaltie s. Explore Error Control Techn iques in detail
b
Draw and explain the block diagram of optical receiver. How it is different from Optical photodiodes. Explain its advantages

Question text is extracted from the official AKTU question paper PDF above. Hindi translations are omitted — every question is printed in English in the original paper. Last verified: 2026-08-23.