OFC Basics Flashcards
1
Q
optical carrier frequency is in the range
1) 10^6 to 10^10 Hz
2) 10^10 to 10^13 Hz
3) 10^13 to 10^15 Hz
4) 10^15 to 10^18 Hz
A
10^13 to 10^15 Hz
the radio wave frequency is about 10^6
Hz and the microwave frequency is about 10^10 Hz
2
Q
Critical angle θc for n1>n2
1) sinθc= n2/n1
2) sinθc= n1/n2
A
sinθc= n2/n1
from snell’s law
3
Q
index of the cladding is approximately ___ % lower than that of the core.
1) 0.5%
2) 1%
3) 2%
4) 3%
A
1%
4
Q
Typical values of refractive index:
1) core: 1.45 and cladding: 1.46
2) core: 1.46 and cladding: 1.45
3) core: 1.47 and cladding: 1.46
4) core: 1.46 and cladding: 1.47
A
1) core: 1.47 and cladding: 1.46
5
Q
buffer coating
1) shock absorber
2) has no optical properties
3) both
A
both
6
Q
rays that pass through the fiber axis
each time, they are reflected
1) meridional rays
2) skew rays
3) both
A
meridional rays
(Skew rays travel down the fiber without
passing through the axis)
7
Q
The path of a ______ ray is typically helical wrapping around and around the central axis. They are ignored in most fiber optics analysis.
1) meridional rays
2) skew rays
3) both
A
skew rays
8
Q
_____ is considered as an optical wave guide
1) Connector
2) OF cable
3) Optical fIber
A
Optical fIber
9
Q
The light stays are confined to the _______
1) core
2) cladding
3) buffer
A
core
10
Q
which one has lower refractive index
1) core
2) cladding
A
cladding
11
Q
A typical of diameters are
1) core: 8μm, cladding: 50μm
2) core: 50μm, cladding: 200μm
3) core: 8μm, cladding: 125μm
4) core: 100μm, cladding: 140μm
A
3 and 4
12
Q
Intrinsic factors of attenuation
1) scattering
2) absorption
3) physical bending
4) stress from manufacturing process
A
1 and 2
(others are extrinsic)
13
Q
________ is caused by small variations in the density of glass as it cools.
1) Rayleigh scattering
2) Rayleigh absorption
3) Intrinsic absorption
4) dispersion
A
Rayleigh scattering
14
Q
factors affecting total attenuation
1) length of fiber
2) wavelength
3) both
4) none
A
both
15
Q
_________ is important at longer wavelengths
1) Rayleigh scattering
2) Intrinsic absorption
A
Intrinsic absorption
(scattering affect shorter wavelength, and prevents the use below 800nm)
16
Q
_________ is important at shorter wavelengths
1) Rayleigh scattering
2) Intrinsic absorption
A
Rayleigh scattering
(scattering prevents the use below 800nm)
17
Q
Extrinsic attenuation caused by
1) Macro bending
2) Micro bending
3) both
A
both
18
Q
This causes energy overlapping and limits information capacity of the fiber.
1) Rayleigh scattering
2) Rayleigh absorption
3) Intrinsic absorption
4) dispersion
A
dispersion
19
Q
Chromatic dispersion refers to
1) Intermodal dispersion (modal dispersion)
2) Intramodal dispersion
3) polarization mode dispersion
A
Intramodal dispersion
20
Q
material dispersion and waveguide dispersion refers to
1) Intermodal dispersion (modal dispersion)
2) Intramodal dispersion (chromatic dispersion)
3) polarization mode dispersion
A
Intramodal dispersion (chromatic dispersion)
21
Q
bandwidth is
1) dependent on length
2) independent on length
A
dependent on length
(the fibre BW is often given in terms of the BW times kilometer product)
22
Q
The fibre BW is often given in terms of
1) the BW times kilometer product
2) the BW per kilometer
A
the BW times kilometer product
23
Q
ratio of optical power is proportional to
1) ratio of current
2) ratio of square of current
A
ratio of current
(for electrical systems, it is ratio of square of current)
24
Q
optical bandwidth is _______ than electrical bandwidth
1) larger
2) smaller
A
larger
25
electrical bandwidth is _______ times optical bandwidth
1) 0.5
2) 0.707
3) 1.707
4) 2
0.707
(electrical bandwidth is lesser than optical bandwidth)
26
_________ has a large core, up to 100 microns in diameter.
1) Step Index multimode Fiber
2) Graded Index multimode Fiber
3) Single-mode Fiber
Step Index multimode Fiber
(best suited for transmission over short distances)
27
_________ is best suited for transmission over short distances
1) Step Index multimode Fiber
2) Graded Index multimode Fiber
3) Single-mode Fiber
Step Index multimode Fiber
(has a large core, up to 100 microns in diameter)
28
light in the core curves helically
1) Step Index multimode Fiber
2) Graded Index multimode Fiber
3) Single-mode Fiber
Graded Index multimode Fiber
29
_____ has a narrow core (nine microns or less)
1) Step Index multimode Fiber
2) Graded Index multimode Fiber
3) Single-mode Fiber
Single-mode Fiber
30
Light thus travels parallel to the axis, creating little pulse dispersion
1) Step Index multimode Fiber
2) Graded Index multimode Fiber
3) Single-mode Fiber
Single-mode Fiber
31
Telephone and cable television networks install millions of kilometers of this fiber every year
1) Step Index multimode Fiber
2) Graded Index multimode Fiber
3) Single-mode Fiber
Single-mode Fiber
32
_____ is used in the majority of outside-plant installations
1) Tight Buffer Tube Cable
2) Loose Buffer Tube Cable
Loose Buffer Tube Cable
33
_____ is used in the majority of inside buildings installations
1) Tight Buffer Tube Cable
2) Loose Buffer Tube Cable
Tight Buffer Tube Cable
34
__________ keep the tensile load away from the fiber.
1) Buffer
2) Yarn strength member
3) Sheath
Yarn strength members
35
A 96 fiber cable is usually
1) Tight Buffer Tube Cable
2) Loose Buffer Tube Cable
Loose Buffer Tube Cable
(The modular design of loose-tube cables typically holds 6, 12, 24, 48, 96 or even more than 400 fibers per cable.)
36
Loose-tube cables can be
1) all-dielectric
2) optionally armored
3) both
both
37
Buffer tubes are stranded around a dielectric or steel central member, which serves as
1) anti-buckling element
2) strength member
3) both
anti-buckling element
38
_________ is designed to endure outside temperatures and high moisture conditions
1) Tight Buffer Tube Cable
2) Loose Buffer Tube Cable
Loose Buffer Tube Cable
(The fibers are loosely packaged in gel filled buffer tubes to repel water. Recommended for use between buildings that are unprotected from outside elements)
39
________ is restricted from inside building use
1) Tight Buffer Tube Cable
2) Loose Buffer Tube Cable
Loose Buffer Tube Cable
40
used mainly in Local Area Networks (LAN)
and are not suitable for Long haul applications
1) ITU-T G.651 compliant Multimode fibers
2) ITU-T G.652 Compliant Single Mode fibers
3) ITU-T G.653 Compliant Dispersion shifted fiber
4) ITU-T G.654 Compliant Cut-off Shifted fiber
5) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
6) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
7) ITU-T G.657 Compliant Bend Insensitive fiber
ITU-T G.651 compliant Multimode fibers
41
Cheaper transmission devices like lasers etc. make ________ attractive for short distance transmission within the 300 to 500 meters reach.
1) ITU-T G.651 compliant Multimode fibers
2) ITU-T G.652 Compliant Single Mode fibers
3) ITU-T G.653 Compliant Dispersion shifted fiber
4) ITU-T G.654 Compliant Cut-off Shifted fiber
ITU-T G.651 compliant Multimode fibers
42
ITU-T does not have any specification for ______ multimode fibers.
1) OM1 (62.5/125)
2) OM2 (50/125)
3) OM3 (50/125)
OM1 (62.5/125)
43
most common single mode fiber in the world
1) ITU-T G.652 Compliant Single Mode fibers
2) ITU-T G.653 Compliant Dispersion shifted fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.657 Compliant Bend Insensitive fiber
ITU-T G.652 Compliant Single Mode fibers
44
can be used at 1550nm with the use
of dispersion compensation modules.
1) ITU-T G.651 compliant Multimode fibers
2) ITU-T G.652 Compliant Single Mode fibers
3) ITU-T G.653 Compliant Dispersion shifted fiber
4) ITU-T G.654 Compliant Cut-off Shifted fiber
2) ITU-T G.652 Compliant Single Mode fibers
45
designed to utilize the low attenuation window of 1550nm by minimizing the dispersion value at around 1550nm. The purpose was good, but it
generated Non-linear effects in the transmission which caused more troubles.
1) ITU-T G.653 Compliant Dispersion shifted fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
1) ITU-T G.653 Compliant Dispersion shifted fiber
46
suitable for Submarine optical fiber cables and terrestrial ultra long haul optical networks
1) ITU-T G.653 Compliant Dispersion shifted fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
5) ITU-T G.657 Compliant Bend Insensitive fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
(Low attenuation at 1550nm range makes this fiber suitable for 400km span without repeaters. The low attenuation ranges from 0.15 – 0.16 dB/km. )
47
Low attenuation at 1550nm range makes this fiber suitable for 400km span without repeaters.
1) ITU-T G.653 Compliant Dispersion shifted fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
5) ITU-T G.657 Compliant Bend Insensitive fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
(The low attenuation ranges from 0.15 – 0.16 dB/km. suitable for Submarine optical fiber cables and terrestrial ultra long haul optical networks)
48
most suitable for DWDM applications
1) ITU-T G.653 Compliant Dispersion shifted fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
5) ITU-T G.657 Compliant Bend Insensitive fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
49
It has a suitable dispersion value over the entire C-band, which is the spectral operating region for eribium doped optical fiber amplifiers
1) ITU-T G.653 Compliant Dispersion shifted fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.657 Compliant Bend Insensitive fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
It has a positive nonzero dispersion value over the entire C-band, which is the spectral operating region for eribium doped optical fiber amplifiers
50
_______ is the average Differential Group
Delay (DGD) one expects to see when
measuring an optical fiber.
1) Intramodal dispersion
2) Polarization Mode Dispersion (PMD)
Polarization Mode Dispersion (PMD)
51
_________ are known as low water peak fiber having low attenuation at 1360nm through 1480nm, the wavelength range which is not yet used
commonly for transmission.
1) G.652A
2) G.652B
3) G.652C
4) G.652D
3) G.652C
4) G.652D
(. PMD for G.652C fiber is 0.5 ps/sqrt.km, where as for G.652D fibers have a PMD of less than or equal to 0.2 ps/sqrt.km)
52
has more stricter and low dispersion slope which enables to guarantee the DWDM performance in wide wavelength range.
1) ITU-T G.653 Compliant Dispersion shifted fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
5) ITU-T G.657 Compliant Bend Insensitive fiber
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
(It has a positive chromatic dispersion value)
53
The chromatic dispersion changes slower with the wavelength so that dispersion compensation is simpler or not needed. This allows the use of CWDM without chromatic dispersion compensation.
1) ITU-T G.653 Compliant Dispersion shifted fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
5) ITU-T G.657 Compliant Bend Insensitive fiber
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
54
________ became a super hit in the FTTH market
1) ITU-T G.653 Compliant Dispersion shifted fiber
2) ITU-T G.654 Compliant Cut-off Shifted fiber
3) ITU-T G.655 Compliant Non-zero dispersion shifted fiber (NZDSF)
4) ITU-T G.656 Compliant Low Slope Dispersion Non-zero Dispersion shifted fiber
5) ITU-T G.657 Compliant Bend Insensitive fiber
5) ITU-T G.657 Compliant Bend Insensitive fiber
55
ADSS stands for
All-Dielectric Self-Supporting [cables]
56
ADSS cable contain metallic elements (T/F)
F: does not contain
It is non-conductive
57
FRP stands for
fibre-reinforced polymer
(used as a strength member in ADSS cable)
58
_________ is used as a strength member in ADSS cable
FRP: fibre-reinforced polymer
59
All dielectric cables are __________ (suitable/not suitable) for applications which are adjacent to aerial power transmission standards lines (T/F)
suitable
60
_________ cable is used in aerial applications
1) ADSS
2) non ADSS
ADSS: All-Dielectric Self-Supporting
61
The basic fiber interconnection
methods
1)de-matable fiber-optic connectors
2) mechanical splices
3) fusion splices
4) all the above
all the above
62
single-mode fibers have small optical cores and hence small MFD. MFD stand for
mode-field diameters (MFD)
63
mostly used for emergency repairs and fiber testing
1) de-matable fiber-optic connectors
2) mechanical splices
3) fusion splices
4) all the above
1 and 2
64
The lowest insertion loss and virtually no back
reflection
1) de-matable fiber-optic connectors
2) mechanical splices
3) fusion splices
4) all the above
fusion splices
(most reliable joint)
65
most reliable joint
1) de-matable fiber-optic connectors
2) mechanical splices
3) fusion splices
4) all the above
fusion splices
(lowest insertion loss)
66
Intrinsic splice loss is due to
1) axial tilt
2) numerical aperture mismatch (multimode)
3) mode field diameter mismatch
4) Fresnel reflections
2 and 3
67
Intrinsic splice loss is due to
1) fiber end quality
2) fiber diameter variation
3) refractive index mismatch
4) Fresnel reflections
2 and 3
68
Extrinsic splice loss is due to
1) axial tilt
2) numerical aperture mismatch (multimode)
3) mode field diameter mismatch
4) Fresnel reflections
1 and 4
69
Extrinsic splice loss is due to
1) fiber end quality
2) fiber diameter variation
3) refractive index mismatch
4) Fresnel reflections
1 and 4
70
single-mode dispersion non-shifted fibers, the dominant fiber-related factor for loss is
1) axial tilt
2) numerical aperture mismatch
3) mode field diameter (MFD) mismatch
4) Fresnel reflections
mode field diameter mismatch
71
In fusion splicer CPA stands for
core profile alignment system (CPA)
72
The cut has to be so precise that it produces an end angle of less than ____ deg on a prepared fiber
1) 0.1 deg
2) 0.5 deg
3) 1.0 deg
0.5 deg
73
It is desirable to limit the average splice loss to less than ___ dB.
1) 0.1 dB
2) 0.5 dB
3) 1.0 dB
0.1 dB.
74
An OTDR uses the effects of
1) Rayleigh scattering
2) Fresnel reflection
3) both
both
75
__________ occur when the light traveling down the fiber encounters abrupt changes in material density that may occur at connections or breaks where an air gap exists
1) Rayleigh scattering
2) Fresnel reflection
3) both
Fresnel reflection
(The strength of the reflection depends on the degree of change in the index of refraction.
The reflection is greater than Rayleigh scattering)
76
light gets reflected back due to changes in the molecular density of the glass. Measuring this light is equivalent to measuring fiber attenuation. (T/F)
T
77
The ________ uses avalanche photodiode (APD)
1) OTDR
2) Power meter
3) Fusion splicer
4) All of the above
OTDR
78
Whenever the light passes through a cleaved end of a piece of fiber, a _______ occurs.
1) Rayleigh scattering
2) Fresnel reflection
Fresnel reflection
79
Fresnel reflection from launch connector causes
1) launch dead zone
2) ringing effect
3) saturation of photo diode
4) all the above
all the above
(saturation of photo diode ->ringing effect and hence dead zone)
80
________ do not generally cause any Fresnel reflections
1) de-matable fiber-optic connectors
2) mechanical splices
3) fusion splices
4) all the above
fusion splices
(Any signs of a Fresnel reflection is a sure sign of a very poor fusion splice.)
81
For _________ events, the event loss can appear as an event gain, displaying a
step-up on the OTDR trace
1) reflective events
2) non-reflective events
non-reflective events
82
LSA method is the most precise way to measure fiber linear attenuation. LSA stands for
Least Squares Approximation
83
LSA method for finding fiber attenuation requires 1) a continuous section of fiber
2) a minimum number of OTDR acquisition points
3) a relatively clean backscatter signal, which is free of noise
4) all the above
all the above
84
__________ can result from a strong reflective event on the fiber
1) Ghosts
2) Noise
Ghosts
85
What is mandrel wrap? for what is it used?
If the event causing the ghost is situated at the end of the fiber, a few short turns around a suitable tool, such as a pen, pencil, or mandrel, will sufficiently attenuate the amount of light being reflected back to the source and eliminate the ghost. This technique is known as a mandrel wrap. A suitable mandrel, will prevent excess bending.
86
Splice gain occurs when
1) different mode field diameters, such as core size, are joined
2) different types of fiber in a multimode
span
3) joining two fibers with different backscatter coefficients
4) all of the above
all of the above
87
Optical power meter calibration is wavelength
1) dependent
2) independent
dependent
88
power meter photodiodes use Silicon for
1) single mode applications
2) multi mode applications
multi mode applications
89
for single mode applications, use photodiodes
1) Silicon (Si)
2) Germanium (Ge)
3) Indium Gallium Arsenide (InGaAs)
2) Germanium (Ge)
3) Indium Gallium Arsenide (InGaAs)
90
____ photodiodes are more adapted to the 1625 nm wavelength (4th window)
1) Silicon (Si)
2) Germanium (Ge)
3) Indium Gallium Arsenide (InGaAs)
Indium Gallium Arsenide (InGaAs)
(Ge photodiodes good for 1310 and 1550 but drop off rapidly at the 1600 nm)
91
The difference between the maximum input and the minimum sensitivity of the power meter is termed the ____
1) dynamic range
2) allowed range
dynamic range
92
VFL stands for
Visual Fault Locator
93
Optical Loss Test Sets (OLTS) includes
1) Optical Light Source (OLS)
2) Visual Fault Locator (VFL)
3) both
both
94
the optical loss can vary significantly as the wavelength varies when _______ fiber is used
1) single mode
2) multi mode
multi mode
