The physics of a laser how it works. How the atom interacts with light. I’ll use this knowledge to simulate a working laser. We will learn how Lasers relies on Stimulated absorption, Spontaneous emission, and most importantly: Stimulated Emission This last type interacts with an excited atom, causing it to relax / deexcite. It will send out a photon with the same phase, frequency, polarization and direction. We exploit this principle in a optical cavity, with the atom as a gain medium.

It turns out the pump will cause stimulated emission for the wrong excited state and we need to use a 3 level atom in order to obtain population inversion.

I'll also cover metastable state, phosphorescence, radiationless transitions and photoluminescence.

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  / higgsino  


Longer simulation video:
   • Laser  Simulation only (No talk)  



0:00 Introduction
0:18 1.1: Atom and light interaction
1:53 1.2: Phosphorescence
2:40 1.3: Stimulated emission
4:10 2.1: The Optical cavity
5:19 2.2: Overall plan for LASER
6:20 2.3: Population inversion problem
7:43 3.1: The 3 level atom
8:18 3.2: Photoluminescence
9:03 3.3 Radiationless transitions
10:25 4.1: A working LASER
11:44 4.2: Coherent monochromatic photons