Study Questionnaire about Fiber Optics

• What are the three parts of a fiber optic data link?

A. Transmitter, optical fiber, receiver
B. Transmitter, optical fiber, optical connectors
C. Optical fiber, optical connectors, receiver
D. Optical fiber, optical connectors

• Fiber optics uses what medium to send information?

A. Electrons C. Photons
B. Link 11 D. Light

• The fiber optic transmitter has which of the following functions?

A. Amplifies the optical signal
B. Converts the electrical input signal to an optical signal
C. Converts the input optical signal to an electrical signal
D. Amplifies the output electrical signal

• Fiber optic system use what two types of optical sources?

A. LED and APD
B. PIN diodes and LED's
C. LEDs and laser diodes
D. Laser diodes and APDs

• The optical source performs which of the following functions?

A. Amplifies the optical signal
B. Amplifies the electrical signal
C. Launches the optical signal into the fiber
D. Converts the optical signal to an electrical signal

• An optical detector has which of the following purposes?

A. To convert an optical signal into an electrical signal
B. To convert an electrical signal to an optical signal
C. To amplify the optical output signal
D. To generate an optical pulse proportional to the input current

• In fiber optic systems, what are the principal types of detectors used?

A. Integrating spheres
B. Photon counters
C. Photomultiplier tubes
D. PIN photodiodes and APDs

• What are the two basic classifications of fiber optic links?

A. High power and low power
B. Return-to-zero and non-return-to-zero line coded
C. Digital and analog
D. Amplitude modulated and frequency modulated

• In shipboard applications with low data rates (0 to 50 Mbps), which of the follwoing source types will typically be used?

A. 850-nm LEDs only
B. 1300-nm LEDs only
C. Either 850-nm LEDs or 1300 nm LEDs depending on design
D. Lasers

• In an optical source, the input electrical energy is converted to light and which of the following other forms of energy?

A. Gravitational
B. Heat
C. Sound
D. All of the above

• Lasers produce light by what process?

A. Combustion
B. Stimulated emission
C. Spontaneous emission
D. Photosynthesis

• LEDs produce light by what process?

A. Combustion
B. Stimulated emission
C. Spontaneous emission
D. Photosynthesis

• In shipboard applications with low data rates (50 to 200 Mbps), which of the follwoing source types will typically be used?

A. 850-nm LEDs only
B. 1300-nm LEDs only
C. 850-nm LEDs and 1300 nm LEDs
D. Lasers

Advantages of Optical Fiber

The advantages of Optical links compared to wave-guides or copper conductors.

1. Extremely wide system bandwidths
• Certain types of fiber have been tested in the laboratory up to 40Ghz of bandwidth, with no limit in sight.
2. Immunity to electromagnetic interference
• External noise does not affect energy at the frequency of light
• Immune to every knid of electromagnetic noise, even lightning.
3. Lower signal attenuation
• Typical attenuation figures of a 1Ghz bandwidth signal for optical fibers are 0.03 db per 100 ft compared to 4.0 db for both RG-58/U coaxial cable and X-band wave guide
4. Light weight and smaller size
• The US navy once replaces conventional wiring the optical system. In this case, 224 ft of fiber optics weighing 1.52 lb replaced 1900 ft of copper wire weighing 30 lb
5. Lower Cost
• Optical fiber costs are continuing to decline while the cost of copper is increasing
6. Conservation of the earth's resources
• The world's supply of copper is limited while the principal ingredient in glass which is sand is cheap and in virtually unlimited supply.
7. Safety
• The dielectric nature of optic fibers eliminates the spark hazard.
  

History About Fiber Optics

Optical Fiber Transmission refers to the transmission of signals for communications using light frequency (10 raised to 14 - 10 raised to 15) carrier with extremely high bandwidth through a low-loss glass optical waveguide.

• "Smoke Signals" - the "first optical signal" used by North American Indians, Chinese, Egyptians, Assyrians and Greeks. They vary messages by changing color (burning barks), vary size and space (period) between each puff. During night time, combinations of torches on high mountain peaks are used.
• In 1893, Claude Chappe (a French doctor) developed the "OPTICAL TELEGRAPH"
• In 1850, Electric Morse Telegraph was invented, which eventually replaced the optical telegraph.
• In 1870's, the English inventor Tyndall, demonstrated that "light could be made to travel through a bent water jet". This established the principle of optical transmission in light conductors.
• In 1930
  
• In 1880, Alexander Graham Bell first attempt at using a beam of light for carrying information with his "Photophone". The maximum transmission of light waves for any useful distance through earth's atmosphere is impractical because of
  
1. Water Vapor
2. Oxygen
3. Air particles that absorb and attenuate the signals at light frequencies.
• In 1930, J.L. Baird (English) & C.W. Hansell (American) received the patents for scanning and transmitting television images through "uncoated fiber cables".
• In 1958, Charles H. Townes (American) & Arthur L. Schawlow (Canadian) wrote a paper regarding the use of "LASER" and "MASER".
• In 1962, "semiconductor LASER" was invented.
• In 1967, K.C. Kao & G.A Bockham of England proposed the "cladded fiber cables". During that time, fiber optic cables limited optical transmission to short distances due to high looses 1,000 dB/km.
• 1970, Kapron, Keck and Maurer of Corning Glass Works in USA developed an optical fiber with losses of less than 2 dB/km.
• Now, Fiber Optic Cable (FOC) loss is less than 0.2 dB/km.