Post on 14-Mar-2020
RubyLaser
RubyLaser
Nd:YAG Laser
Nd:YAGLaser– ActiveMaterial
Nd3+ trappedinaYAGhost(typicaldopinglevel:1%atom).
Nd3+ SubstituteY3+ ionsinthecrystallinehostYAG=YttriumAluminumGarnet– Y3Al5O12
4-LevelLaserLevelsareprovidedby4felectronsofNd3+ andweaklyinfluencedbytheCrystallinestructure
[1]SpringerHandbookofLasersandOptics– TrägerEd.
LevelStructure
A.M.PARAMETERS: ��1k = 230µs
�e = 2.8⇥ 10�19cm�2
Nt = 1.38⇥ 1020 ions/cm2
�⌫ ' 0.15 THz
Nd:YAGLaser– SpectroscopyofActiveMedium
[1]SpringerHandbookofLasersandOptics– TrägerEd.[2]).Svelto– PrinciplesofLasers– 4th Edition
AbsorptionSpectrum
EmissionSpectrum
l=1064nm– PrincipalEmission
l=946nm–notsoenergetic(lamppumping)l=1319nm– notsoenergetic(diodepumping)
Roddiameter:3-6mmRodlength:5-15cm
YAG“Family”– DifferentActiveMaterials
ManyionscanbeusedtodopeYAGcrystal.thisgivesrisetoabroadvarietyofsolidstatelasersbasedonYAGhosts.
Differentdopingionscorrespondtodifferentwavelengths.
Nd:YAGLaser- Performances
REGIMES:CW– Q-Switch(10ns)– ModeLocked(psrealm– passiveML)[1]SpringerHandbookofLasersandOptics– TrägerEd.[2]O.Svelto,PrinciplesofLasers– 4th Edition
PUMPING:Lamps(XeforCWandKrforPulsedregime)->3%EfficiencyDiode(longitudinalandtransversalconfiguration)->10%Efficiency
OUTPUTPOWER:LampPumped:uptoafewkW(1-3kW)inCWDiodePumped:15W(CW)forlongitudinallypumpedabove100W(CW)fortransversallypumped
LampPumping
DiodePumping
Longitudinal
Transversal
Nd:YAGLaser– Applications(1/2)
DRILLING- QSMARKING
WELDING- QS
P 50-100 WE 5-10 J
⌧pulse 1-10 msRp 10-100 Hz
Upto2kW.GreatadvantagewithrespectToCO2 becauseNd:YAGcanbeconveyedinopticalfibers
[2]O.Svelto,PrinciplesofLasers– 4th Edition
Nd:YAGLaser– Applications(2/2)EYE-SURGERY
RESEARCH:AssubstituteofAr-Laserforpumping(Nd:YAGfrequencydoubled@532nm– green)
MEDICALAPPLICATIONS:Coagulationandtissueevaporation– CWupto50WPhotoablation(eyesurgery)- QS
RANGING- QS
E 100 mJ⌧pulse 5-20 nsRp 1-20 Hz
[2]O.Svelto,PrinciplesofLasers– 4th Edition
Er-Laser– Why?
[3]G.P.Agrawal,NonlinearFiberOptics– AcademicPress
SiO2 spectrum.Minimallossesat1.55µm
ThemostefficientLasersourceinthatregionisEr-Laser!
Opticalfibersarewidelyusedinopticaltelecommunicationsystems.TheyaremadeofSiO2.Weneedtofindagoodlasersourceattelecomwavelength(1.55µm)
Er:Yb:Glass/Fiber :NotpossibletodirectlyPumpEr3+.ResonantpumpWithYb3+Diodepumped@980nm
Er-Laser– Basics
Upperlevellifetime(Er:Yb:Glass)ca.8ms
TheErbiumLaserisathreelevelsystem!!!!
Erbium Ytterbium
ClassBlaser
ErbiumFiberLaser
Q-Switching[4]E 9 µJ
⌧pulse 420 nsRp 0.1-2 kHz
[4]Tzong-YowTsaiet.al.,Opt.Expr.18,10049(2010)[5]H.Zhanget.al.,Opt.Expr.17,17630(2009)
ModeLocking[5]E 7.3 nJ
⌧pulse 415 fsRp ' 6 MHz
Mainapplicationintelecomsystems!
Π polarization1
0.8
0.6
0.4
0.2
0Inte
nsity
[arb
. uni
ts]
wavelength [nm]400 500 600 700 800 900
Absorbance Fluorescence
Ti:Sa laser
HeNe
Terminalmirror(flat) Terminalmirror(concave)
mirrorholder(endings)
Brewsterwindow
cathode
endofcapillary
gasdischargecapillary
Springs(tocenterthecapillaryend)
mirrorholder
glass-tube
He-NeLaser
HeNemixture~4-7mbarandaneoncontentof~10%
gamma= 6.6x106 s-1
k= 3.1x106 s-1
He-NeLaser
CO2laser
O OC
sym. stretching mode
O OC
antisym. stretching mode
O O
C
bending mode
(1000)
(0000)
(0200)
(0110)
(0001)
1000
2000
3000
0
∆E ~18 cm-1
10.6 µm
9.6 µm
v=0
v=1
CO2 N2
CO2 laser
gamma= 3x104 s-1
k= 9.6x106 s-1
gamma/k= 3.125x10-3
3levelsystem