Lecture 18 - Lecture 18 Lecture 18 Various laser types...

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Lecture 18 1 © Jeffrey Bokor, 2000, all rights reserved Lecture 18 Various laser types Laser pumping processes: Electrons: Gas discharge or electron beam Optical: a) incoherent – flashlamp, arc lamp, solar b) coherent – another laser Electrical current: Semiconductor diode laser Gas discharge laser construction – Ne excited states glued mirrors 1 s 2 2 s 2 2 p 5 3 s 1 s 2 2 s 2 2 p 5 3 p 1 s 2 2 s 2 2 p He/Ne Energy Levels ~ ~ He Ne 0 135,000 165,000 155,000 145,000 recall: 1eV 8066 cm 1 = Energy cm 1  1 s 2 s 2 S 1 2 p 5 5 S 1 s 2 1 S 1 1 s 2 s 2 S 3 1 s 2 2 s 2 2 p 6 1 S 1 1 S 1 2 p 5 4 s 2 p 5 3 s 2 p 5 3 p 2 S 3.39 m 3 S 2 p 5 4 p 1.15 m 6096Å 6678Å 5944Å 6328Å Main Ne sign emission 2.395 m 1 S
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Lecture 18 2 © Jeffrey Bokor, 2000, all rights reserved Optically pumped lasers Nd:YAG laser Diode pumping Q-switching Upper-level lifetime in Nd:YAG is ~ 100 sec 1. Modulator has low transmission 2. Population builds up in upper state 3. Inversion density >> threshold, but no lasing 4. Modulator switches to high transmission 5.
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Lecture 18 - Lecture 18 Lecture 18 Various laser types...

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