Fiber Optic Communications Flashcards
concepts
1
Q
It is based on the principle that light in a glass medium can carry more information over longer distances than electrical signals can carry in a copper medium.
A
FIBER OPTIC COMMUNICATIONS
2
Q
It is the science, study, or technology dealing with light transmission.
A
FIBER OPTICS
3
Q
It is the medium, channel or path where light signals travel.
A
OPTICAL FIBER
It is also known as a light pipe or light guide
4
Q
It is the internal material of the fiber, specifically the central part of the fiber where the light propagates.
A
CORE
innermost
5
Q
It is the material of lower refractive index that surrounds the core.
A
CLADDING
n(core)>n(clad)
6
Q
A special lacquer, silicone br acrylate coating applied to the outside of the cladding to seal and preserve the fiber’s strength and protects fiber from moisture.
A
PROTECTIVE COATING
reduces stress corrosion (static fatigue) caused by high humidity
7
Q
Provides the cable additional protection against abrasion and shock.
A
BUFFER JACKET
8
Q
Encapsulates the buffer jacket, which increases the tensile strength of the overall cable assembly.
A
STRENGTH MEMBERS
9
Q
It is where the entire cable assembly is contained.
A
POLYURETHANE OUTER JACKET
outermost
10
Q
Optical Fiber Types
A
PCP (plastic-clad-plastic)
PCS (plastic-clad-silica)
SCS (silica-clad-silica)
11
Q
Made up of plastic core and plastic cladding
A
PCP (plastic-clad-plastic)
has higher attenuation
12
Q
Made up of glass core and plastic cladding
A
PCS (plastic-clad-silica)
has less attenuation
13
Q
Made up of glass core and glass cladding
A
SCS (silica-clad-silica)
best propagation characteristics
14
Q
Optical fiber type that does not exist
A
SCP (Silica-Clad-Plastic)
n(core)>n(clad)
15
Q
Cable configuration in which each fiber is contained in protective tube, with polyurethane inside it that prevents water intrusion
A
LOOSE TUBE CONFIGURATION
16
Q
Cable configuration wherein fiber is sorrounded by primary and secondary buffer comprised of Kevlar Yarn
A
CONSTRAINED FIBER CONFIGURATION
17
Q
Cable configuration which includes a steel central member and a layer of Mylar tape wrap to increase the cable’s tensile strength.
A
MULTIPLE STRANDS CONFIGURATION
18
Q
Optical Fiber Coding Scheme (EIA 598)
A
“Bakit O-orgasm Ganun? Bakit Sobrang Wild? Ratrat Biyak Yan, Virgin Raw Ako?!”
blue, brown, black, red, rose
19
Q
An electromagnetic wave having a very high oscillation frequency and very short wavelength
A
LIGHT
20
Q
Band of high frequencies that is too low to be seen by the human eye
A
INFRARED
range: 770 nm- 10^6 nm
21
Q
The band of light frequencies to which the human eye will respond
A
VISIBLE
range: 390 nm-770 nm
22
Q
The band of frequencies that are too high to be seen by the human eye
A
ULTRAVIOLET
range: 10 nm-390 nm
23
Q
Refers to the range of wavelength that can be
satisfactorily used in an optical fiber.
A
WINDOW
24
Q
1 micron
A
10^-6 m
25
1 Angstrom
10^-10 m
26
It states that when visible light or high frequency electromagnetic radiation illuminates a metallic surface, electrons are emitted (Photoelectric Effect).
Planck's Law
27
Photon energy
E = hf
28
It is the science of measuring only light waves that are visible to the human eye.
PHOTOMETRY
29
It is described in terms of luminous flux density in lumens per unit area.
LIGHT INTENSITY
30
It measures light throughout the entire electromagnetic spectrum.
RADIOMETRY
31
Also known as** radiant flux**. It measures the rate at which electromagnetic waves transfer light energy.
OPTICAL POWER
32
Bouncing of light
REFLECTION
33
Bending of light
REFRACTION
34
Separation of light
DISPERSION
35
Scattering of light
DIFFRACTION
36
Bands where optical fiber systems operate
INFRARED BANDS
37
Most important optical property that is used in fiber optics
REFRACTION
38
The spectral separation of white light is known as the
PRISMATIC REFLECTION
39
Refracted the **most** in prismatic reflection
VIOLET WAVELENGTHS
40
Refracted the **least** in prismatic reflection
RED WAVELEGTHS
41
Refractive index
n = c/vp = 1/vf = √εr
| vp - velocity propagation, vf - velocity factor
42
Line that is perpendicular to the interface between the two media.
NORMAL LINE
43
Angle at which the propagating ray strikes the interface with respect to the normal.
ANGLE OF INCIDENCE
44
Angle formed between the propagating ray and the normal after the ray has entered the second medium.
ANGLE OF REFRACTION
45
Minimum angle of incidence at which light ray may strike the interface of two media and result in an angle of refraction of 90°.
CRITICAL ANGLE
46
Conditions for Total Internal Reflection
n(core) > n(clad)
θinc > θcrit
47
Occurs when angle of incidence is less than the critical angle
REFRACTION
48
When angle of incidence equal to the critical angle, light travels through the
Interface
| clad core boundary
49
Occurs when the angle of incidence is greater than the critical angle
TOTAL INTERNAL REFLECTION
50
When incident ray travels from less dense to more dense, refracted ray moves ________ the normal
toward
| LMT (less dense to more dense, toward)
51
When incident ray travels from more dense to less dense, refracted ray moves ________ the normal
AWAY
| MLA (more dense to less dense, away)
52
Maximum angle between the axis of an optical fiber and a ray of light entering a fiber
ACCEPTANCE ANGLE
| or acceptance cone half angle
53
Equal to twice the maximum acceptance angle
ACCEPTANCE CONE ANGLE
| apex angle
54
Light gathering ability of an optical fiber
NUMERICAL APERTURE
55
The relationship between the incident rays and the refracted rays at a boundary between mediums with different indexes of refraction describes what law?
SNELL'S LAW
56
Light travels only in one path, and its core has smaller diameter
SINGLE MODE
57
Light travels in two or more paths, and its core has larger diameter
MULTIMODE
58
Chromatic (wavelength) dispersion occurs in this mode of propagation
SINGLE MODE
59
Modal dispersion (pulse spreading) occurs in this mode of propagation
MULTIMODE
60
Graphical representation of the value of the refractive index across the fiber
INDEX PROFILE
61
Core is surrounded by an outside cladding with uniform refractive index less than that of the core
STEP INDEX
62
Index of refraction of the core is not constant, instead it varies smoothly and continuously over the diameter of the core
GRADED INDEX
| highest n at the center, decreases graually
63
Has minimum dispersion, wider bandwidth and higher transmission rate, suited for very long haul applications
SINGLE MODE STEP IDEX
64
The key parameter that describes the mode structure of a fiber
V NUMBER
65
Esier to couple light into and out of the fiber, large light-to-fiber aperture, inexpensive, simple to manufacture and best suited for short haul applications
MULTIMODE STEP INDEX
66
The light rays are propagated in different paths and has a non-uniform refractive index.
MULTIMODE GRADED INDEX (GRIN)
| intermediate fiber
67
Multimode glass optical fiber core diameter
62.5 ±3 µm
| typical value
68
Multimode glass optical fiber cladding diameter
125 ±3 µm
69
Results in reduction in the power f the light wave as it travels down the cable
ATTENUATION (POWER LOSS)
70
It is analogous to power dissipation in copper cable, wherein impurities in the fiber absorb the light and convert it to heat
ABSORPTION LOSS
71
Absorption loss caused by valence electrons
ULTRAVIOLET ABSORPTION
72
Absorption loss caused by photons of light
INFRARED ABSORPTION
73
Absorption loss caused by OH ions
ION RESONANCE ABSORPTION
74
It is due to the imperfections in the fiber that are formed during manufacturing process.
MATERIAL (RAYLEIGH) SCATTERING LOSS
75
When light rays strike these impurities, they are diffracted, this is known as
RAYLEIGH SCATTERING LOSS
76
It occurs to non-coherent light sources where light contains combination of different wavelengths
CHROMATIC (WAVELENGTH) DISPERSION
77
It can occur only in single mode of propagation, and can be eliminated by using a monochromatic source such as an ILD.
CHROMATIC (WAVELENGTH) DISPERSION
78
Predominantly caused by small bends and kinks in the fiber
BENDING (RADIATION) LOSS
79
Bending caused by manufacturing
MICROBEND
80
Bending caused by installation
CONSTANT-RADIUS BEND
81
It is also known as pulse width dispersion, which is caused by the difference in the propagation times of light ray that take different path down the fiber, and can occur only in multimode fibers.
MODAL DISPERSION (PULSE SPREADING)
| multimode only
82
In multimode propagation, dispersion is often expressed as
BDP (bandwidth distance product) or BLP (bandwidth length product).
83
It is the difference between the absolute delay times of the fastest and slowest rays of light propagating down a fiber of unit length
PULSE SPREADING CONSTANT
| nanoseconds per km
84
It occurs in some types of optical junctions: source-to-fiber, fiber-to-fiber and fiber-to-detector connections.
COUPLING LOSS
85
Devices that converts electrical energy into light energy
OPTICAL SOURCES
86
Common spectracl width of LEDs
30 nm to 50 nm
87
Surface emitters LEDs
HOMOJUNCTION LEDs
88
Edge emitters LEDs
HETEROJUNCTION LEDs
| better than homo
89
# Comm
Common spectral width of injection laser diode (ILD)
1 nm to 3 nm
90
ILDs emit ____ light; LEDs emit ____ light
coherent(orderly); incoherent (disorderly)
91
Devices which converts light energy to electrical energy
LIGHT DETECTORS
92
It is a depletion layer photodiode and is probably the most common device used as a light detector in fiber optic communications system.
PIN DIODE
| operates opposite of LED
93
Has a PIPN structure, more sensitive than PIN diodes and requires less amplification
AVALANCHE PHOTODIODE (ILD)
94
measure of conversion efficiency of a photodetector
RESPONSIVITY
| ampere/watts
95
time it takes a light-induced carrier to travel across the depletion region
transit time
96
range of wavelength values that can be used for a given photodiode
SPECTRAL RESPONSE
97
Minimum optical power a light detector can receive
LIGHT SENSITIVITY
| dBm or dBu
98
LEDs are usually used for ________ speed applications. ILDs and LASERS are used for ________ speed applications.
low; high
99
____ are usually used for low speed applications and used together with **LEDs**. ____ are used for high speed applications and used together with** ILDs or LASERS**.
PIN diodes; APDs
100
is the wavelength equivalent of bandwidth.
LINEWIDTH
101
Holds the fiber securely in place
FERRULE
| optical fiber connector
102
means permanently attaching the end of one cable to another
SPLICING
103
cutting the cable
CLEAVING
104
It is the leakage current that flows through a photodiode with no light input. It is caused by the thermally generated carriers in the diode.
DARK CURRENT
105
uses micro-manipulators to bring the prepared ends of the fiber into closed alignment
FUSION SPLICING TECHNIQUE
106
splits the signals into two channels, but the polarizations in each output are orthogonal.
POLARIZATION SPLITTER
107
it combines two or more input channels into one output channel.
COMBINER
108
it is a splitter that couples very little light into the monitor port.
MONITOR
109
it is a non-reciprocal device that isolates one input from the other
DIRECTIONAL COUPLER
110
it is a combiner that joins two or more source signals of differing wavelengths
MULTIPLEXER
111
it is a three-terminal device that allows light entering at terminal 1 to be coupled out of terminal 2-with 100% efficiency, also, light entering at terminal 2 is coupled out of terminal 3 with 100% efficiency.
CIRCULATOR
112
the use of two or more light sources at different wavelengths separately modulated with the same fiber.
WDM (wavelength division multiplexing)
113
Single pulses that can travel through a medium with no dispersion
SOLITON
114
designed for high data rate capability of fiber optic transmission
SONET (synchronous optical network)
| north american standard by ANSI (1988)
115
the basic modular signal for SONET digital hierarchy
SYNCHRONOUS TRANSPORT SIGNAL (STS)
116
STS-1 Frame consists of ____ columns and ____ rows of ____ -bit bytes for a total of ____ bytes. It has frame length of ____ us
90; 9; 8; 810; 125
117
portion of the STS frame structure that allows for OAM&P (Operations, Administration, Maintenance, and Provisioning).
OVERHEAD
118
revenue-producing traffic being transported and routed over the SONET network.
| portion of STS Frame
SYNCHRONOUS PAYLOAD ENVELOPE
119
carry low-speed signals across the SONET network.
VIRTUAL TRIBUTARY
120
the basic modular signal for the SDH digital hierarchy.
SYNCHRONOUS TRANSPORT MODULE (STM)
121
The base level for SDH is the STM-1 with a bit rate of
155.52 Mbps
122
STM-1 Frame consists of ____ columns and ____ rows. It has frame length of ____ us (the same as for PCM).
270; 9; 125
123
it is the first 9 columns of the STM frame structure
OVERHEAD
124
It the revenue-producing traffic being transported and routed over the SDH network.
PAYLOAD
125
it is the payload entity that travels across the network, being created and dismantled at or near the service termination point.
VIRTUAL CONTAINER
126
is a 100 Mbps LAN signaling standard intended for use with fiber optics but also used with coax.
FDDI (fiber distributed data intrface)
127
is use of fiber optic cable for telephone subscriber connections.
FITP (fiber in the loop)
128
is the use of fiber for all of a telephone system except for the subscriber loop.
FTTC (fiber to the curve)
129
it is the optical counterpart of the STS
OPTICAL CARRIER (OC)
