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this is the 31st lecture and the FO a series of lectures

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I fiber optics and this lecture

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a technique used to share an optical fiber

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among man! different signals "all simultaneousl!

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wavelength division multiplexing uses that

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fact that light can be traveling down the fiber

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simultaneousl! from man! different colors of wh!

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without mixing or interfering with each other

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we've seen this all the time

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I liked being dispersed fire prism where all the different colors is like a

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are able to move through the air simultaneousl!0:

until the! reach the prism which separates them into their component

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colors

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we can do exactl! the same sa!ing &pple fiber

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so let's use a large core plastic fibre

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and some laser pointers to see exactl! what's happening

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wavelength division multiplexing is used

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this is a large

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stick fiber and will use a red laser pointer

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&ndrew modulated to show how signals are t!picall! modulated

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now to I read laser pointer

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lets a degree ma(or pointer and as !ou can see

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isn't bothered at all b! the second light traveling in the fiber

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if we had other colors and laser pointers

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we can even had more colors and this is a good example how to callers

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can be transmitted simultaneousl! down the fiber

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without interfering with each other

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*hester show

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+rance for the collars let's reverse it will take the green light and send it

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down the center is a her

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and then we'll start sending red light through separatel!#:#0

and as !ou can see exactl! the same thing happens

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the green light is not bother to now and the modulation is a red light

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in the same fighter

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this technique was first used for wavelength division multiplexing

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in sending ,te two signals over 1 !r

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the same time !ou simpl! need to cut waste

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to couple the light and two and have the fighter to different sources to differ

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receivers and optical filters those filters

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stop one color flight and let the other through

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can carr! different signals to read detectors

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simultaneousl! actuall! that pine s!stems passive optical networks

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except the!'re sending fiber signals and opposite directions

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and different colors the same technique applies

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it's t!pical

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sense networks toda! to use wavelength division multiplexing

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I'm ver! long distance lakes here we use dense wavelength division multiplexing

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made more than sixt! four channels tightl! spaced

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with fiber amplifiers for repeaters we also can use coarse wavelength division

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multiplexing

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with fewer channels wider spaced$:7

for those we need low water - h!per

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which allows asked to use the entire spectrum

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a single mode fiber in assistance toda!

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its preferred to and waved flags instead of having more fibers

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and !ou can use it for bi directional signals over single fiber

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as is used in fiber to the home

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s!stem has its own wa! flag

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range ./. use tightl! space wa! flanks

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and the angers roughl! 14 1 1) 1 animators

4:$7that's the range where fiber amplifiers can t!picall! be used

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and long2distance s!stems to happen if I the signal

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for repeaters coarse wavelength division multiplexing

4:1uses broader space wa! flanks over the full range

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I've 1## 1)1 animators

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before angers single2mode fiber but it needs low2water peak fiber

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so the high attenuation in the water peaks as attenuate the signals

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for critical wa! flax

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awa! flanks used in ./.

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and */. are quite different because

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./. has so man! different channels

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the lasers are spaced 0 points

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3ana meters massive one animator:$#

and the stabilit! of these wa! flanks

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requires using expensive .+ lasers

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coarse wavelength division multiplexing

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uses lasers at twent! 3ana meter spacing

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so it's much less critical on the wa! flanks

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have all the different lasers

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im long2distance networks fiber amplifiers are use

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to regenerate to signup it's not a repeater is (ust an amplifier

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it does it convert the signal to an electrical signal and then back to an

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and actuall! works more like a fiber amplifier

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where the incoming signal goes in .ecember be in doubt fiber

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along fiber amplifier fiber itself

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he's erbium2doped fiber amplifiers work in that 140

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1)1 at a meter range that's used for dense wavelength division

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multiplexing look for another video soon on fiber amplifiers

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where

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terms that uses wavelength division multiplexing

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it's not uncommon on longer lengths of fiber

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to task spectral attenuation because we need to ensure

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that over the entire band that we're doing our wavelength division7:0#

multiplexing

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that the fiber can transmit the signals

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with roughl! equal attenuation s!stems

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tested this wa! are generall! tested with roadwa! flank sources

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to cover the entire wavelength range we have

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another video I'm testing long2distance networks

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that goes into more detail I'm testing

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testing

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do !ou have

7:$p5m5 s!stem ur */. s!stem isn't all that difficult

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after is it wa! flights have been the multiplexed

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into each individual wavelength channel an! standard power meter 10 &sia power

7:4%back the individual services ma!be

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requiring testing for /avelink as the wavelength is critical

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for making sure that the s!stem operates properl!

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if the wa! for exchanges the d multiplexing and multiplexing

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have the wavelength ma! not work properl!

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before he has man! other videos lectures on fiber optics

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in for missus cabling hats and fiber optics

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and hands2on videos for both fiber and copper

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on our 6ouube sacked please be sure to check those out

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and see what others !ou're interested in where the fiber optic &ssociation:$

the International professional societ!

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a fiber optics promoting fiber

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through education certification

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and testing find out more on our website

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www the + awa!

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gotta work