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LASERS A short introduction on how “lasing” is achieved.

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Presentation on theme: "LASERS A short introduction on how “lasing” is achieved."— Presentation transcript:


2 LASERS A short introduction on how “lasing” is achieved

3 Applications of Lasers To annoy people at the movies Lasers in Industry Lasers in Geography Lasers in Astronomy Lasers in Communication

4 3 ways radiation interact with the energy levels of atoms Spontaneous Emission –atom*  atom + photon Induced absorption –atom + photon  atom* Induced/stimulated emission –Responsible for laser creation –Atom* + photon  atom + 2photons –2 photons travel in exactly the same direction with the same energy and in phase

5 Importance of Induced Emission Laser = Light Amplification by Stimulated Emission of Radiation Simple Model –Why won’t this work? Population Inversion –More atoms in upper/excited state than lower state –Done by pumping the ground states to excited states –Once pumped – decay rapidly (sp. em) to a metastable state –More atoms in a metastable state than ground state –Achieves population inversion

6 Lasing Transition Can happen once population inversion is maintained Transition from metastable state to the ground state Atom* + photon  atom + 2photons

7 3 level laser Ruby laser 1960 by Theodore Maiman

8 4 level laser Relieves population inversion difficulty

9 Summary How A laser Works

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