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Telephony > Fiber Optics > Flashcards

Fiber Optics Flashcards

1
Q

is essentially a waveguide for light

A

Optical Fiber

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2
Q

index of refraction of the cladding is ___ that of the core, causing rays of light leaving the core to be refracted back into the core

A

Less Than

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3
Q

LASER meaning:

A

Light Amplification by Stimulated Emission of Radiation

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4
Q

Advantages of optical fiber include:

A
  • Greater bandwidth than copper
  • Lower loss
  • Immunity to crosstalk
  • No electrical hazard
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5
Q

Optical fibers work on the principle of

A

Total Internal Reflection

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6
Q

is closely related to the critical angle and is often used in the specification for optical fiber and the components that work with it

A

Numerical Aperture

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7
Q

is twice that given by the numerical aperture

A

Angle of Acceptance

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8
Q

Multimode propagation will cause ____, which results in the spreading of pulses and limits the usable bandwidth

A

Dispersion

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9
Q

Types of index profiles:

A
  • Step-Index

- Graded-Index

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10
Q

the index of refraction changes radically between the core and the cladding

A

Step-Index

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11
Q

is a compromise multimode fiber, but the index of refraction gradually decreases away from the center of the core

A

Graded-Index

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12
Q

increases with the bandwidth of the light source

A

Dispersion

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13
Q

Basic types of fiber-optic cables: (2)

A
  • loose tube cable

- tight-buffer cable

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14
Q

all the stress of cable pulling is taken up by the cable’s strength members and the fiber is free to expand and contract with temperature

A

loose tube cable

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15
Q

are cheaper and generally easier to use

A

tight-buffer cable

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16
Q

Splice & Connector Losses:

A
  • Axial or angular misalignment
  • Air gaps between the fibers
  • Rough surfaces at the ends of the fibers
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17
Q

is a permanent connection

A

Splice

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18
Q

is a removable connection

A

Connector

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19
Q

Coupler Construction (2)

A
  • transmissive coupler

- reflective coupler

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20
Q

Optical emitters operate on the idea that electromagnetic energy can only appear in a discrete amount known as a ___

A

Quantum

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21
Q

is form of junction diode that is operated with forward bias

A

LED

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22
Q

generate coherent, intense light of a very narrow bandwidth

A

Laser Diode

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23
Q

The most common optical detector used with fiber-optic systems is the ___

A

PIN diode

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24
Q

PIN diode is operated in ___

A

Reverse bias mode

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25
Q

The creation of electron-hole pairs due to the absorption of a photon of incoming light may set off avalanche breakdown, creating up to 100 more pairs

A

Avalanche Photodiode (APD)

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26
Q

band of light frequencies that is too high to be seen by the human eye with wavelengths ranging between 770nm and 10^6 nm

A

Infrared

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27
Q

band of light frequencies to which the human eye will respond with wavelengths ranging between 390 nm and 770 nm

A

Visible

28
Q

band of light frequencies that are too low to be seen by the human eye with wavelengths ranging between 10 nm and 390 nm

A

Ultraviolet

29
Q

The coating helps protect the fiber from moisture, which reduces the possibility of occurrence of a detrimental phenomenon called ___ or static fatigue cause by high humidity

A

Stress Corrosion

30
Q

Types of optical fibers commonly used today: (3)

A
  • plastic core and cladding
  • glass core, plastic cladding (or PCS - plastic-clad-silica)
  • glass core, glass cladding (or SCS - silica-clad-silica)
31
Q

Process of decaying from one energy level to another energy level is called ___

A

Spontaneous decay or spontaneous emission

32
Q

Is the science of measuring only light waves that are visible to the human eye

A

Photometry

33
Q

Measures light throughout the entire electromagnetic spectrum

A

Radiometry

34
Q

How a light ray reacts when it meets the interface of two transmissive materials that have different indexes of refraction

A

Snell’s Law

35
Q

Defined as the minimum angle of incidence at which a light ray may strike the interface of two media and result in an angle of refraction of 90 degrees or greater

A

Critical Angle

36
Q

Defined as the maximum angle in which external light rays may strike the air/glass interface and still propagate down the fiber

A

Acceptance angle or Acceptance cone half-angle

37
Q

Closely related to acceptance angle and is the figure of merit commonly used to measure the magnitude of the acceptance angle

A

Numerical Aperture (N.A.)

38
Q

Simply means path

A

Mode

39
Q

has a central core with a uniform refractive index

A

Step-index Fiber

40
Q

Has no cladding and the refractive index of the core is nonuniform, it is highest in the center of the core and decreases gradually with distance toward the outer edge

A

Graded-index Fiber

41
Q

Type of optical fiber configurations: (3)

A
  • single-mode step index optical fiber
  • multimode step-index optical fiber
  • multimode graded-index optical fiber
42
Q

Predominant losses in optical fiber cables: (6)

A
  • absorption loss
  • material or Rayleigh scattering loss
  • chromatic or wavelength dispersion
  • radiation loss
  • modal dispersion
  • coupling loss
43
Q

The light rays that escape represent loss in light power called __

A

Rayleigh scattering loss

44
Q

Occurs as a result of differences in the thermal contraction rates between the core and cladding material

A

Microbending

45
Q

Is caused by the differences in the propagation times of light rays that take different paths down a fiber

A

Modal dispersion OR Pulse spreading

46
Q

Characteristics of Light Detectors: (4)

A
  • responsivity
  • dark current
  • transit time
  • spectral response
  • light sensitivity
47
Q

A measure of the conversion efficiency of a photodetector; Its the ratio of the output current of a photodiode to th input optical power and has the unit of A/W

A

Responsivity

48
Q

The leakage current that flows through a photodiode with no light input

A

dark current

49
Q

The time it takes a light-induced carrier to travel across the depletion region of a seminconductor

A

transit time

50
Q

range of wavelength values that a given photodiode will respond

A

spectral response

51
Q

The minimum optical power a light detector can receive and still produce a usable electrical output signal

A

Light Sensitivity

52
Q

bandwidth of an analog communications system as a percentage of its carrier frequency

A

bandwidth utilization ratio

53
Q

Materials commonly used for the buffer jacket include: (6)

A
  • steel
  • fiberglass
  • plastic
  • flame-retardant polyninyl chloride (FR-PVC)
  • Kevlar Yarn
  • Paper
54
Q

Wavelengths that are refracted the most

A

Violet

55
Q

Wavelengths that are refracted the least

A

Red

56
Q

indicates what signal frequency can be propagated down through a given distance of fiber cable and is expressed mathematically as the product of distance and bandwidth

A

Bandwidth length product (BLP) or Bandwidth distance product (BDP)

57
Q

Losses caused by imperfect physical connections

A

Coupling Loss

58
Q

Lateral or axial displacement between two pieces of adjoining fiber cables

A

Lateral Displacement

59
Q

Sometimes called END SEPARATION; When splices are made, the fibers should actually touch

A

Gap Displacement/Misalignment

60
Q

Loss that if less than 2deg, will be 0.5 dB

A

Angular Displacement/Misalignment

61
Q

Loss incurred if the ends of 2 adjoining fibers are not polished and fit together squarely

A

Imperfect Surface Finish

62
Q

Type of laser that use a mixture of helium and neon enclosed in a glass tube

A

Gas Lasers

63
Q

Type of laser that uses organic dyes enclosed in a glass tube for an active medium

A

Liquid Lasers

64
Q

Type of laser that uses a solid, cylindrical crystal such as ruby for the active medium

A

Solid Laser

65
Q

Type of laser that ae made from semiconductore p-n junctions and are commonly called ILDs

A

Semiconductor Laser

Telephony (9 decks)

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