Deck 18: Fiber Optics

Question 1

Loss due to the light breaking up and escaping through the cladding.

A) absorption
B) dispersion
C) macrobending
D) micro bending

Answer 1

C

Question 2

The wavelength of red light is:

A) 520 nm.
B) 1600 nm.
C) 680 nm.
D) 430 nm.

Answer 2

C

Question 3

The wave length at which the material and waveguide dispersion cancel one another is called:

A) critical wave length
B) mode-field diameter
C) zero-dispersion wavelength
D) none of the above

Answer 3

C

Question 4

Pulse dispersion is mainly caused by:

A) variable path lengths due to the light signal traveling down the fiber in different modes.
B) noise picked up by the light signal.
C) use of too high power, highly directional laser sources to generate the light signal.
D) excessive use of repeaters through the fiber optic cable length.

Question 5

The core size of multimode fiber is approximately:

A) 50 to 100 nm
B) 7 to 10 um
C) 50 to 100 um
D) 25 to 35 nm

Question 6

The material surrounding the core of the optical waveguide is called:

A) strapping
B) glasing
C) cladding
D) padding

Question 7

Which of the following are typical wavelengths used in fiber optics?

A) 850 nm
B) 1310 nm
C) 1550 nm
D) A and C
E) all of the above

Question 8

The amount of bending of the light into a material depends on the of that material:

A) refractive index
B) reflective index
C) wavelength of light
D) critical angle

Question 9

The trapping of light in a fiber results from:

A) dispersion
B) numerical aperture.
C) step index.
D) total internal reflection.

Question 10

The diode laser is preferred to the light-emitting diode in systems that have:

A) predictable failure rates.
B) long distance paths.
C) moderate band to wideband requirements.
D) low error rate requirements.

Question 11

Fiber cables with core diameters of about 7 to 10 m.

A) multi mode
B) mode field
C) single mode
D) step-index

Question 12

The numerical aperture of a fiber:

A) is a basic specification which indicates its ability to accept light and shows how much light can be off axis and still be propagated.
B) the acceptance angle where the output light is no greater than 10 db down from the peak value.
C) defines the half-angle of the cone of acceptance for propagated light in the fiber.
D) all of the above

Question 13

Which of the following dispersions is not exhibited in single-mode fiber?

A) waveguide
B) modal
C) material
D) zero

Question 14

Which is not a major criteria in selecting a specific type of fiber optic cable?

A) refractive index
B) signal losses
C) ease of light coupling and interconnection
D) bandwidth

Question 15

Which of the following is an important characteristic of light detectors?

A) response speed
B) dark current
C) responsivity
D) all of the above

Question 16

Determine the maximum fiber length if the maximum bit rate is 56 Kbps and the dispersion is 6 ns/km.

A) 200 Km
B) 0.000595 Km
C) 595 Km
D) 10 Km

Question 17

An estimation of how long a fiber optic cable can be for a given bit rate and dispersion for successful data communications to occur is referred to as:

A) a frequency response.
B) a power budget.
C) a detector system check.
D) an error rate analysis.

Question 18

Loss caused by very small mechanical deflections and stress on the fiber.

A) absorption
B) micro bending
C) dispersion
D) macro bending

Question 19

An optical fiber and its cladding have refractive indexes of 1.535 and 1.386 respectively. Calculate NA.

A) 0.369
B) 0.463
C) 0.897
D) 0.66

Question 20

A term used to describe the transmission of data over hundreds or thousands of miles.

A) long haul
B) short haul
C) haul
D) medium haul

Question 21

The broadening of an optical pulse due to different path lengths taken through the fiber by different modes is called:

A) modal dispersion
B) chromatic dispersion
C) polarization mode dispersion
D) all of the above

Question 22

The broadening of an optical pulse due to different propagation velocities of the spectral components of the light pulse is called:

A) polarization mode dispersion
B) chromatic dispersion
C) modal dispersion
D) all of the above

Question 23

A coherent light source is one that is:

A) easy to decode
B) due to a defective laser
C) spectrally pure
D) easy to understand

Question 24

A long-term method where two fibers are fused or welded together is called:

A) mechanical splicing
B) core alignment
C) fusion splicing
D) none of the above

Question 25

A piece of test equipment that sends a light pulse down the fiber and measures the reflected light is called:

A) reflecometer
B) an OTDR
C) TDR
D) light pulser

Question 26

The protocol standard for optical transmission in long-haul communication is:

A) STS
B) SONET
C) OC
D) FDDI

Question 27

Common synonymous terms for a fiber optic strand are: (select all that are correct)

A) glass
B) light pipe
C) fiber
D) conduit

Question 28

1000Base LX is:

A) Gigabit Ethernet
B) FDDI
C) OC-3
D) FTTH

Question 29

A dispersion compensating fiber

A) yields close to zero dispersion in the 1550 nm region
B) acts like an equalizer
C) cancels dispersion effects
D) all of the above

Question 30

A jelly like substance that has an index of refraction much closer to the glass than air is called:

A) index matching gel
B) alignment gel
C) splice gel
D) framing gel

Question 31

The term for incorporating the propagation of several wavelengths in the 1550nm range of a single fiber is called

A) fiber bragg gating
B) dense wave length division multiplex
C) multiplexed fiber
D) distributed feedback

Question 32

RSL in regards to an optical receiver is:

A) received signal level
B) radiometry signal level
C) radio signal level
D) none of the above

Question 33

The attenuation of an optical signal is due to:

A) scattering
B) absorption
C) macro bending
D) none of the above
E) all of the above