16/01/2025 16:22
Fiber optics exam 1
Total internal reflection
Trapping light in a material (fiber optic) by surrounding it by another material with a
lower refractive index is the phenomenon of
Index of Refraction
Ration of Speed of light in a material/Speed of light in a vacuum
Measure to how much light slows down when entering a material
Attenuation
The reduction in optical power (Loss) as it passes along a fiber, usually expressed in
dB
Optical fiber data link is made of 3 elements
1) Light source
2)Fiber
3) Light Detector
Typical fiber optic data link
1) Transmitter = source driver and light
2) Connectors
3) Cables/Fiber
4)photodiode receiver
Buffer Coating
Physical protection around the Cladding/core
Cladding
Covering around glass that keeps light inside of Core via Total Internal Refraction
Core
Center glass where light travels
Multi mode Step index
1 type of glass
Light travels in straight lines
Multi mode graded index
Many layers of glass in the core
100x faster then Step-Index
Single Mode
Light travels in one mode
NO modal dispersion
Bandwidth increases
CATV
Community Antenna Television
62.5/125
Diameter of core/Diameter of Cladding
Numerical Aperture
Highest angle that light can enter a fiber
Calculated by (difference in the indices of refraction of the core and cladding) via
Snells law
Mode
Direction of light
Single mode - 1 light direction
Multi-mode. - multiple angles of light
Chromatic Dispersion
, 16/01/2025 16:22
Occurs with LED's
Change of light by the prism effect that disperses light into its color wave lengths
which changes the speed of light in a fiber
Advantages of Fiber Optics
Transport more Info
Transport info faster
Transport info farther
More secure
Light Flow of a graded index multi-mode fiber
Index Profile approximates a parabola - Helps modal dispersion
Modal Dispersion
Light makes it to the end of the fiber at different times
3 ways to fabricate fiber
Modified Chemical Vapor Dispersion
Outside Vapor Dispersion
Vapor Axil Dispersion
Graded Index multi-mode application
Data communication
Step-index multimode application
Efficient source power coupling
Single Mode application
Long distance telecommunications
Bandwidth is is limited by 2 things
Modal dispersion
Chromatic dispersion
LANS reason for fiber
Upgradability
CATV's reason for fiber
Reliability
Telecom's reason for fiber
High Bandwidth and distance advantages
FTTC
Fiber to the curb
FTTH
Fiber to the home
AM analog systems made fiber:
Cost effective for CATV Applications
Unshielded twisted pair cable was adopted for computer networks because it was
Already used for telephone
Cheaper than coax
Easier to install than coax
Cat 5e replacement with fiber , most of the additional cost is in
Electronics
Which are not necessary in a centralized fiber optic cabling architecture
Repeaters and hubs
Copper Networks can be converted to fiber optics easily using
Media Converters
Buffered Fiber comes in 3 styles
Fiber optics exam 1
Total internal reflection
Trapping light in a material (fiber optic) by surrounding it by another material with a
lower refractive index is the phenomenon of
Index of Refraction
Ration of Speed of light in a material/Speed of light in a vacuum
Measure to how much light slows down when entering a material
Attenuation
The reduction in optical power (Loss) as it passes along a fiber, usually expressed in
dB
Optical fiber data link is made of 3 elements
1) Light source
2)Fiber
3) Light Detector
Typical fiber optic data link
1) Transmitter = source driver and light
2) Connectors
3) Cables/Fiber
4)photodiode receiver
Buffer Coating
Physical protection around the Cladding/core
Cladding
Covering around glass that keeps light inside of Core via Total Internal Refraction
Core
Center glass where light travels
Multi mode Step index
1 type of glass
Light travels in straight lines
Multi mode graded index
Many layers of glass in the core
100x faster then Step-Index
Single Mode
Light travels in one mode
NO modal dispersion
Bandwidth increases
CATV
Community Antenna Television
62.5/125
Diameter of core/Diameter of Cladding
Numerical Aperture
Highest angle that light can enter a fiber
Calculated by (difference in the indices of refraction of the core and cladding) via
Snells law
Mode
Direction of light
Single mode - 1 light direction
Multi-mode. - multiple angles of light
Chromatic Dispersion
, 16/01/2025 16:22
Occurs with LED's
Change of light by the prism effect that disperses light into its color wave lengths
which changes the speed of light in a fiber
Advantages of Fiber Optics
Transport more Info
Transport info faster
Transport info farther
More secure
Light Flow of a graded index multi-mode fiber
Index Profile approximates a parabola - Helps modal dispersion
Modal Dispersion
Light makes it to the end of the fiber at different times
3 ways to fabricate fiber
Modified Chemical Vapor Dispersion
Outside Vapor Dispersion
Vapor Axil Dispersion
Graded Index multi-mode application
Data communication
Step-index multimode application
Efficient source power coupling
Single Mode application
Long distance telecommunications
Bandwidth is is limited by 2 things
Modal dispersion
Chromatic dispersion
LANS reason for fiber
Upgradability
CATV's reason for fiber
Reliability
Telecom's reason for fiber
High Bandwidth and distance advantages
FTTC
Fiber to the curb
FTTH
Fiber to the home
AM analog systems made fiber:
Cost effective for CATV Applications
Unshielded twisted pair cable was adopted for computer networks because it was
Already used for telephone
Cheaper than coax
Easier to install than coax
Cat 5e replacement with fiber , most of the additional cost is in
Electronics
Which are not necessary in a centralized fiber optic cabling architecture
Repeaters and hubs
Copper Networks can be converted to fiber optics easily using
Media Converters
Buffered Fiber comes in 3 styles
