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23/10/2013, 20:15
... Inc.
opticalwaveutilizingthestimulatedemissioninamediumwherepopulation
inversionisproducedbyexcitation.Thestateofthemediumwith
populationinversioniscalledthelaser-activestate.Insemiconductor
injectionlasers,populationinversionisrealizedthroughinjectionof
minoritycarrierswithahighenergyinthevicinityofap–njunctionby
supplyingaforwardcurrent.Althoughinthischapterthepossibilityof
enhancementofopticalpowerbystimulatedphotonemissionwasshown
basedonconsiderationofthestatesofanelectronandtheenergy
eigenstatesoftheopticalfield,thisdiscussiondoesnotensurethepossibility
ofenhancementofopticalamplitudeincludingthephase,i.e.,thecoherent
amplificationofanopticalwave.Thepossibilityofcoherentamplification
willbediscussedonthebasisofananalysisusingthedensitymatrixin
Chap.3.Spontaneousemissionalsotakesplaceinparalleltothelaser
action.Itaffectssignificantlythelaserperformances;e.g.,itgivesrisetothe
laseroscillationthresholdandthequantumnoiseintheoutputlight.
REFERENCES
1.W.Heitler,TheQuantumTheoryofRadiation,OxfordUniversityPress,
Oxford(1954).
2.A.Yariv,QuantumElectronics,JohnWiley,NewYork(1967).
3.L.I.Schiff,QuantumMechanics,McGraw-Hill,NewYork(1968).
4.Y.Fujii,OpticalandQuantumElectronics(inJapanese),Kyoritsu,Tokyo(1978).
5.M.SargentIII,M.O.Scully,andW.E.Lamb,Jr,LaserPhysics,Addison-
Wesley,Reading,MA(1974).
6.D.Marcuse,PrinciplesofQuantumElectronics,AcademicPress,NewYork
(1980).
7.K.Shimoda,IntroductiontoLaserPhysics(inJapanese),Iwanami,Tokyo
(1983).
8.P.MeystreandM.SargentIII,ElementsofQuantumOptics,Springer,
Berlin(1991).
9.T.Suhara,QuantumElectronics(inJapanese),Ohmsha,Tokyo(1993).
36Chapter2
Copyright ... Hamiltonians of the electron, of the field energy,
and of the interaction energy, respectively, and H
0
describes a Hamiltonian
for total energy under an assumption that there is no interaction. ... emission of a photon of a mode of
frequency !
m
¼ðE
i
E
f
Þ=hh takes place. If the electron is initially in the
lower energy level E
i
(E
i
< E
f
), incidence of an optical wave of frequency
!
m
¼ðE
f
...