Optics Flashcards
Optical wave guide or “light pipe”
Optical fiber
An optical source is usually a/an
LED or laser
Typical optical detector
Photodiode.
Greek letter used to represent wavelength
Lambda
Speed of light in a vacuum
C, ~300million meters per second
299,792 kilometers per second.
186,282 miles per second
Visible spectrum
400Thz-790Thz
750nm-380nm
1Ghz in wavelength
300cm
54 MHz in wave length
5.6 m
1550 nm in frequency
193.5 Thz
1310 nm to frequency
229 Thz
1000nm in frequency
300 Thz
750 nm in frequency
400 Thz.
Also red light
3 Phz in wavelength
10 um
455 nm to frequency
659 Thz
Also violet light
480 nm to frequency
625 Thz
Also blue light
550 nm to frequency
545 Thz
Also green light
750 nm to frequency
400 Thz
Optical fiber index of refraction
1.47
In telecom fiber both the core and cladding is made of
Plastic, glass or silica
Protective cover is made of
One or more layers of polymer or other protective substances
At the output of the fiber the varying path delays result in a
Smearing of the output signal as a function of time.
Smearing of the output signal as a function of time. AKA
Modal dispersion
As the diameter of the core of the fiber decreases the number of paths for light
Also decreases.
Typical multi mode fiber core size
50-62.5 um
Typical single mode fiber core diameter
9 um
Typical cladding size for both single and multi mode fibers
125 um
Fiber bent to sharply results in
Macrobend
Tool to use finding macro bends
Visual fault locator
Bend radius for fiber
5-10 times the outer diameter unloaded
15 times the outer diameter loaded
1 inch or 3cm for single mode fiber
Causes high loss by allowing light to escape into the cladding
Macrobend
Tiny kinks or nicks in fiber during manufacturing or by mishandling
Microbends
Components of an optical fiber cable.
Optical fiber Buffer tube Strength member Water blocking elements Armor Jacket
Contains multiple bundles of fibers.that are loosely grouped in a hollow buffer tube that surrounds a central member
Central loose tube
Has groups of fibers contained in buffer tubes to facilitate fiber identification and fiber splicing
Stranded loose tube.
Typical fiber bundle contains how many fibers.
12 fibers
Has multiple fibers arranged in a flat row
Ribbon fiber or stacked ribbon fiber
Directly codes digital 1s and 0s as pulses of light
Baseband digital modulation
Varies the intensity of light in direct proportion to the analog signal that is applied
Analog intensity modulation
Is robust and can be sent long distances over optical fibers
Baseband digital modulation
Does not require linear optical sources or optical detectors
Baseband digital modulation
BDM requires optical sources to be turned up and down how offten
Millions or billions of times per second
A seniconductor device that converts light into an electrical current
Photodiode
Highly linear optical sources and detectors are required for high quality
Analog intensity modulation
A 1 dB change in optical loss will result in what for the electrical output
2 dB change
Analog intensity modulation can use this as an input and will produce this as an output
RF signal
Constructed using special fibers that have been doped(infused with) special impurities
Fiber amplifier
Used where high optical power is required at the input of the optical fiber
EDFA
Used where links of 75 mi are possible using a wavelength of 1550 nm
EDFA
EDFA’s produce an optical power in the range of
+26 dBm
Almost half a watt
Can cause severe eye damage and burn connectors if not handled properly
Popular because of spetral purity, linearity and excellent power output levels
DFB
Distributed feed back
Can produce +11 dBm
Has low output and high dispersion
Fabre-Perot
An optical technology allowing multiple optical signals onto a single fiber by using different wavelengths
Wave division multiplexing
Architecture that directly connects the headend to a customer premise location
FTTP
Conventional HFC networks can also be called
Fiber to the node
Removes all amplifiers between the optical node and customer premise
Fiber deep.
ODN
Optical distribution network
Describes networks in which the fiber extends to within several hundred miles of the customers home or not all the way to customers home
FTTP
This is a passive optical splitter
Multiplexing point
By reducing the amount of hardline cable we limit exposure to
Ingress and egress
Mid split frequency range up and down
5-88 up
108- 1002 down
All MHz
Take in fiber from headend or hub and distribute it to within 1000’ of the customer home
Multiplexing point
R-ONU acts a an interface between these two things
ODN and the subscriber coaxial wiring.
Ethernet standard for EPON
802.3ah
A router with Ethernet interfaces on one side and coax RF interfaces on the other side
CMTS
GPON ODN interfaces with
ONT
Optical network terminal
EPON ODN interfaces with
ONU
Optical network unit
Use this to examine optical fibers
Video fiber scope
When cutting or splicing you should work above a
Tacky mat
Fiber working table should be
A flat smooth surface
Chemical resistant
Dark preferably black
Floor of the work area for fiber should be
Smooth material such as a coated or polished concrete
Made of a non patterned flooring material
What should you use to pick up fiber remnants
Teflon tipped tweezers
Damage to eye from amplified light
Retinal burns or
Cataracts
Affected tissue shows burn characteristics and damage due to
Denaturation of protein
Used to detect the output of a fiber optic line
Infrared detection card
