Laser Physics I - University of Alabama at Birminghampeople.cas.uab.edu/~mirov/Lectures 3-4 ch2 fall...

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Laser Physics I PH481/581-VT (Mirov)

Optical Frequency Amplifiers

Lectures 3-4 chapter 2

Fall 2015C. Davis, “Lasers and Electro-optics”

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Optical Frequency Amplifiers

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Homogeneous Line Broadening

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e(+iot

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Inhomogeneous Broadening

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Homogeneous Line Broadening

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Inhomogeneous Broadening

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Optical Frequency Amplification with a Homogeneously Broadened Transition

B21

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‘Pump area

Z2

'212

22 1

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Cross section of emission ( , )8c A g

gN Ng

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The Stimulated Emission rate in a Homogeneously Broadened Transition

2'21

21 3( ) ( , )8

eA c I IW gh h

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Optical Frequency Amplification with Inhomogeneous Broadening

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L

• – ’ : distance from line center• L : Lorentz half-width• D : Doppler half-width

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'2 2

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2 ln 2( , ) Normalized Voight Profile( )

2( ) ln 2 2 ln 2ln 2 , , and ,

where is shift in central frequency due to molecules collision

t

D

L

D D D

y eg dty x t

y x t

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Optical Frequency Oscillation - Saturation

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Power output from a laser amplifier

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Inhomogeneous system

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