8.2ApplicationsofQuantumMechanics

8.2ApplicationsofQuantumMechanics - Lasers 8.2 Applications...

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1 8.2 Applications of Quantum Mechanics Lasers Semiconductors Semiconductor devices Lasers A laser is a light source that produces a focused, collimated, monochromatic beam of light. The laser operates using the principle of stimulated emission of light. Stimulated Absorption of light Oscillating electric field at the resonant frequency excited an electron. Eh f ∆= Spontaneous Emission of light This is the normal process of emission e.g. in an atomic arc lamp. Stimulated Emission of light Similar to stimulated absorption except from the excited state. The excess energy is emitted as a photon that is in phase with the incident photon. Probabilities of simulated absorption and emission The probabilities for absorption and emission are the same. Normally absorption dominates emission because most atoms are in the ground state. absorption emission (few atoms) (most atoms)
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2 Laser Need to have more atoms in the excited state than in the ground state i.e. Population Inversion a scheme for producing a population inversion in He Ne laser (collisions) Fast Laser cavity Stimulated Emission is enhanced along the direction of the reflected light giving a collimated light beam.
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This note was uploaded on 06/03/2010 for the course PHYS physics 1c taught by Professor Smith during the Spring '09 term at UCSD.

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8.2ApplicationsofQuantumMechanics - Lasers 8.2 Applications...

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