Optical Communications Mid - I, September - 2014

1.Which of the following wavelengths is one of the Optical Windows?
  • 800-900 nm
  • 655nm
  • 350-500 nm
  • All the above
Answer: A
2.For a give Optical fiber, the refractive index of core is given as 1.5, refractive index of cladding is given as 1.47, Numerical aperture is given by _________
  • 0.56
  • 0.3
  • 0.11
  • 0.45
Answer: B
3.For an Optical fiber having a Numerical Aperture of 0.4, the acceptance angle for Meridional rays is given by
  • 33.60
  • 45.60
  • 23.60
  • 54.60
Answer: C
4.Loss that occur due to microscopic variations in material density from compositional fluctuations or defects during fiber manufacture are
  • Absorption loss
  • Scattering loss
  • Bending loss
  • Core-cladding loss
Answer: B
5.Chalgenide glass is used in the manufacturing of optical switches and fiber lasers due to
  • More Stability
  • High Optical Non Linearity
  • More resistant to High Temperatures
  • All the above
Answer: B
6.Material Dispersion can be reduced by choosing sources with
  • Narrower Spectral output width
  • Broader Spectral output width
  • Operating with longer wavelength
  • Both a and d
Answer: D
7.Intermodal dispersion in multimode fibers can be minimized with the use of
  • Step Index fibers
  • Graded Index fibers
  • Both a and b
  • cannot be minimized
Answer: B
8.Which of the following Splicing techniques automatically performs lateral, longitudinal and angular alignment
  • Fusion Splicing
  • V-Groove Splicing
  • Elastic tube Splicing
  • Both b & C
Answer: C
9.For optical fiber communication requiring bandwidth greater than 200 MHz, the following optical source is preferred.
  • Edge Emitter LED
  • Surface Emitter Led
  • Semiconductor Injection Laser diode
  • Ruby Laser
Answer: C
10.Which of the following is used to split the broad spectral emission of LED into narrow spectral slices?
  • Waveguide grating array
  • V- grove Splicing
  • Distributed Brass reflector
  • None of the above
Answer: A
11.A Fiber splice is a ______________________ joint between two fibers.
Answer: Permanent or Semi-permanent
12.Laser Consists of an active medium to produce ____________________
Answer: Optical Amplification
13._______________ Dispersion occurs due to variation of refractive index of the core material as a function of wave length.
Answer: Material
14.In case of graded index fiber, for triangular profile V number can be increased by a factor of ______________
Answer: √3
15.An extended temperature range at which glass becomes fluid is called _____________ temperature.
Answer: Melting
16.The angle at which the refracted ray will be parallel to the interface is known as ______________
Answer: Critical angle
17.A fiber having a core of constant refractive index and a cladding of a slightly lower refractive index than core is known as _______________
Answer: Step Index Fiber
18.__________________ is defined as the number of electron hole carrier pairs generated per incident photon of energy hγ.
Answer: Quantum Efficiency
19.Two Popular Butt joint alignment designs are ________________ and _____________
Answer: Straight Sleeve and Tapered Sleeve
20.The fundamental mode that propagates in an optical fiber is _______________
Answer: HE11