Which among the following is used as receiver in fiber optic communication?

This question was previously asked in
RRB ALP Electronics Mechanic 23 Jan 2019 Official Paper (Shift 2)
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  1. LDR
  2. LED
  3. Photo Transistor
  4. LASER Diode

Answer (Detailed Solution Below)

Option 3 : Photo Transistor
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Detailed Solution

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The correct answer is option 3.

Fiber Optic Receivers

  • Fiber optic receivers convert light signals into electrical signals for use by equipment such as computer networks.
  • These electro-optical devices consist of an optical detector, a low-noise amplifier, and signal conditioning circuitry.
  • After the optical detector converts the incoming optical signal into an electrical signal, the amplifier increases it to a level suitable for additional signal processing. 
  • Two types of semiconductors are used in fiber optic receivers i.e. silicon semiconductors such as photo-transistors and indium gallium arsenide semiconductors.
  • Photo Transistors are used in short-wavelength receivers with a range of 400 nm to 1100 nm.
  • Indium gallium arsenide semiconductors are used in long-wavelength receivers with a range of 900 nm to 1700 nm.

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