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Lasers

Amplified light from the stimulated emission of radiation.

  1. Intro to Lasers

  2. Stimulated Emission

  3. Population Inversion

  4. 3 and 4 Level Systems

  5. Construction and Laser Diodes

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1. Introduction to Lasers

Everyone loves playing with lasers and they are really useful for many experiments in A Level Physics. The monochromatic light of one wavelength is great for showing diffraction and many other wave phenomena.

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2. Stimulated Emission

To understand how lasers work we need to look at the three processes that occur within an atom when it interacts with a photon: absorption, spontaneous emission or even stimulated emission.

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3. Population Inversion

In order to allow an in increase in the total number of photons emitted by a sample there needs to be more atoms held in the high energy excited state. Here I explain why.

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4. 3 and 4 Level Systems

In reality, a three or four level energy system is used to allow a population inversion, with the atoms excited by pumping them with an external source of energy.

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5. Construction and Laser Diodes

Here I show you the general construction of a laser and also how the small semiconductor laser diodes are constructed. These have hundred of uses and can be found everywhere in the modern world.

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