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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Ruby lasers

Ruby [Al2O3:Cr 3+(~0,05%)] is an aluminum oxide crystal

in which some of the aluminum atoms have beenreplaced with chromium atoms. Chromium gives ruby its

characteristic red color and is responsible for the lasing

behavior of the crystal. Chromium atoms absorb green

and blue light and emit or reflect only red light. For a ruby

laser, a crystal of ruby is formed into a cylinder. A fully

reflecting mirror is placed on one end and a partially

reflecting mirror on the other. A high-intensity lamp isspiraled around the ruby cylinder to provide a flash of 

white light that triggers the laser action.

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Cr:Al2O3 energy level diagram levels

E 

4A2

4T1

2A

694nm

Blue-greenlight from aflash lamp

Fast decay

Lasertransition

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Typical system

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

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Ruby laser

First laser: Ted Maiman

Hughes Research Labs1960

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Typical laser beam

Laser beam

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Nd:YAG laser

Relevant

energy

levels of Nd

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Typical Nd:YAG laser

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Elliptical cavity

Double elliptical cavities with two flash lamps

Helical flash

lamp

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Nd 3+ :YAG (single crystal, nano-powders in the form of disks are

being developed)

1064 nm : emission wavelength

CW ~100W

Pulsed~100J(ms)

Q-switched ~100 GW(10-20ns)Glass as host, pulsed

oscillator-amplifier chains for fusion

Frequency doubling: 532nm (green); 1st harmonic2nd harmonic, 3rd harmonic

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

1. Active Material: Al2O

3,YAG, BeAl

2O

4,YVO4

2. Beam Modification (Q-switching): Al2O3 

3. Frequency mixing : LiNbO3, KDP,ADP,KTP

CsLiB6O10 (CLBO), ……….. 4. Components (windows, lenses etc): ZnSe,

CdTe, NaCl, Al2O3, ……. 

Organic materials are catching upDoped crystals/pure crystals

Crystals used in lasers

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

1. Solution Growth

2. Growth from the melt

3. Growth from vapour

The fundamentals are relatively simple butthe interactions involved and the

individuality of the different materials are

so complex that theoretical predictionshave met with very limited success.

To-date CRYSTAL GROWTH REMAINS AN ART.

Crystal growth techniques

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Crystals grown from solution

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LPU/PHY 803/Laser Technology Autumn Term 2010-11

Lecture on ruby and Nd:YAG lasers for internal use in LPU only 

Typical melt growth

Melt Initial growth

Final crystal