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InsemFeb 20232019 patternBE E&TC

Fiber Optic Communication (FOC) SPPU Insem Question Paper Feb 2023

All 4 questions from this SPPU insem paper, as printed. Read them here or open the PDF.

Open the PDFMost repeated FOC questions
Subject code
404190
Pattern
2019 pattern
Exam
Insem
Session
Feb 2023
Max. marks
30
Time
1 Hour
Semester
VIII
Paper code
[6010]-70

Printed for: B.E. (E & TC) (In s em)

Instructions to the candidates

  1. Answer Q.1 or Q.2, Q.3 or Q.4.
  2. Neat diagrams must be drawn wherever necessary.
  3. Figures to the right indicate full marks.
  4. Assume suitable data, if necessary.

Questions

  1. Q1

    1. a)

      Using simple ray theory, describe the mechanism for the transmission of light within an optical fiber. With the help of suitable diagram discuss what is meant by the acceptance angle and numerical aperture of the fiber.

      [5]
    2. b)

      A manufacturer wishes to make a silica-core, step-index fiber with V = 75 and a numerical aperture NA = 0.30 to be used at 820 nm. If n1 = 1.458. What should the core size and cladding refractive index be?

      [5]
    3. c)

      Describe with the aid of simple ray diagrams. the MMSI and SMSI fiber. Compare advantages and disadvantages of these two types of fibers.

      [5]

  2. Q2

    1. a)

      Explain the key elements of the optical fiber communication system with neat diagram and identify the three transmission windows on the fiber attenuation curve.

      [6]
    2. b)

      The mean optical power launched into an optical fiber link is 1,5 mW and the fiber has an attenuation of 0.5dB/Km. Determine the maximum possible link length without repeaters when the minimum mean optical power level required at the detector is 2  W.

      [4]
    3. c)

      Classify and explain the various loss mechanisms in optical fibers. 2

      [5]

  3. Q3

    1. a)

      The radiative and nonradiative recombination lifetimes of the minority carriers in the active region of a double heterojunction LED are 60 ns and 100 ns respectively. Determine the total carrier recombination lifetime and the power internally generated within the device when the peak emission wavelength is 0.87  m at a drive current of 40 mA.

      [6]
    2. b)

      Describe with the help of suitable diagram the mechanism giving the emission of light from an LED. State useful properties of LED to be used in optical fiber communication.

      [5]
    3. c)

      State the semiconductor materials used for various optical sources.

      [4]

  4. Q4

    1. a)

      Explain the following terms i) Absorption ii) Spontaneous Emission iii) Stimulated Emission

      [5]
    2. b)

      Compare LED with LASER w.r.t. following points: i) Output Power ii) Spectral width iii) Coupled Power iv) E/O efficiency v) Speed

      [5]
    3. c)

      A GaAs laser operating at 900nm has a 300  m length and refractive index n=4.3. Find the following i) Frequency spacing ii) Wavelength spacing iii) Number of modes 

      [5]