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Laser &Laser & OpticalOpticalFibersFibers

Prepared by :Prepared by : Nikhil KumarNikhil Kumar

M.TechM.Tech in Laser Technologyin Laser TechnologyRoll noRoll no--001131201006001131201006


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ContentsContents

Fiber LaserFiber Laser

Advantages of Fiber LaserAdvantages of Fiber Laser

Disadvantages of Fiber LaserDisadvantages of Fiber Laser

Design and manufactureDesign and manufacture Fiber Disk LasersFiber Disk Lasers

Optical fibersOptical fibers

Use

ofOptical

fibersUse

ofOptical

fibers

Advantages of Optical fibersAdvantages of Optical fibers

Disadvantages of Optical fibersDisadvantages of Optical fibers


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Fiber LaserFiber LaserAA fiberfiber laserlaser is a laser in which the active gainis a laser in which the active gainmedium is anoptical fiber doped with raremedium is anoptical fiber doped with rare--earthearthelements such as erbium,elements such as erbium, ytterbiumytterbium and thulium.and thulium.They are related to doped fiber amplifiers, whichThey are related to doped fiber amplifiers, whichprovide light amplification without lasing. Fiberprovide light amplification without lasing. Fiber

nonlinearities, such as stimulated Ramannonlinearities, such as stimulated Ramanscattering orfourscattering orfour--wave mixing can also providewave mixing can also provide

gain and thus serve as gain media for a fiber laser.gain and thus serve as gain media for a fiber laser.


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Advantages ofFiber LaserAdvantages ofFiber Laser

High Power: ease ofcooling in long fiberHigh Power: ease ofcooling in long fiberHigh Stability: spliced wave guiding fibersHigh Stability: spliced wave guiding fibers

High Reliability: operate 24/7 for decadesHigh Reliability: operate 24/7 for decades

Lower total cost ofownershipLower total cost ofownership

Low jitter and low amplitude noiseLow jitter and low amplitude noise

Compact form factorCompact form factorImmune to tough environmental changesImmune to tough environmental changes

TurnTurn--key Operationkey Operation


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Disadvantages ofFiberDisadvantages ofFiber

LaserLaserPulse pedestals from non-ideal optical

spectrum for higher energy pulses.

Undesired nonlinearoptical effects at high

pulse energy, such as self-phase modulation

and Raman scattering.


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Design & ManufactureDesign & Manufacture

Unlike most other types of lasers, the laser cavity infiber lasers is constructed monolithically by fusionsplicing different types offiber ; fiber Bragggratings replace conventional dielectric mirrors to

provide optical feedback. Another type is thesingle longitudinal mode operationofultra narrowdistributed feedback lasers where a phase-shiftedBragg grating overlap the gain medium. Fiberlasers are pumped by semiconductor laser diodesor by otherfiber lasers.


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Power ScalingPower ScalingRecent developments infiber laser technology

have led to a rapid and large rise in achieveddiffraction-limited beam powers from diode-pumped solid-state lasers. Due to theintroductionof large mode area (LMA) fibersas well as continuing advances in high powerand high brightness diodes, continuous-wavesingle-transverse-mode powers from Yb-doped

fiber lasers have increased from 100 W in 2001to >50 kW. Single mode lasers have reached10 kW inCW power .


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Fiber disk lasersFiber disk lasers

Another type offiber laser is the fiber disk laser.

In such, the pump is not confined within the

cladding of the fiber (as in the double-cladfiber), but pump light is delivered across the

core multiple times because the core is coiled

on itself like a rope. This configuration issuitable for power scaling in which many

pump sources are used around the periphery of

the coil.


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Optical FiberOptical Fiber


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Optical FiberOptical Fiber

Anoptical fiber is a flexible, transparent fiber madeofvery pure glass (silica) not much wider than a

human hair that acts as a waveguide, or "light

pipe", to transmit light between the two ends of thefiber . Optical fiber typically consists ofa

transparent core surrounded by a transparentcladding material with a lower index of refraction.Light is kept in the core by total internal reflection.


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Uses of Optical FibersUses of Optical Fibers

Opticalfibers

offer huge c

ommu

nicati

oncapacity. A single fiber can carry the

conversations ofevery man, woman and childon the face of this planet, at the same time,twice over. The latest generations ofopticaltransmission systems are beginning to exploit asignificant part of this huge capacity, to satisfythe rapidly growing demand for datacommunications and the Internet.


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Advantages of Optical FibersAdvantages of Optical Fibers

CapacityCapacity

Size and Weight

Running Costs

Security


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CapacityCapacityOptical fibers carry signals with much less energy loss

than copper cable and with a much higher

bandwidth . This means that fibers can carry more

channels of informationover longer distances andwith fewer repeaters required.


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Size and WeightSize and Weight

Optical fiber cables are much lighter and thinnerOptical fiber cables are much lighter and thinner

than copper cables with the same bandwidth. Thisthan copper cables with the same bandwidth. This

means that much less space is required inmeans that much less space is required in

underground cabling ducts. Also they are easierforunderground cabling ducts. Also they are easierfor

installation engineers to handleinstallation engineers to handle..


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SecuritySecurity

Optical fibers are much more difficult to tapinformationfrom undetected; a great advantage for

banks and security installations. They are immune to

Electromagnetic interference from radio signals, carignition systems, lightning etc. They can be routed

safely through explosive orflammable atmospheres,

for example, in the petrochemical industries or

munitions sites, without any riskof ignition.


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Running CostsRunning Costs

The main consideration in choosing fiber wheninstalling domestic cable TV networks is the

electric bill. Although copper coaxial cable can

handle the bandwidth requirement over the shortdistances ofa housing scheme, a copper system

consumes far more electrical power thanfibre,

simply to carry the signals.


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Disadvantages of Optical fiberDisadvantages of Optical fiber1. Enormous Bandwidths

2. Low transmission loss

3. Immunity to cross talk

4. Small size and weight

5. Signal security

6. Electrical Isolation

7. Ruggedness and flexibility

8. Low cost and availability9. Reliability


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