Introduction to Computational Physics - Class Project


Uri Ezra - Physics, Technion.

A three level LASER consists of atoms that oscillate among three electronic levels. The top level ( denoted by |c> ), is very unstable and decays to the middle level ( denoted by |b> ), on time scale of 10E-13 [sec]. The middle one is more stable and decays to the ground state ( |g> ) on a time scale of 10E-7 [sec]. This property of the atoms makes it possible to make a "Population Inversion" ( a population that does not satisfy "Boltzman's equation") of the electrons. Population inversion is obtined by lighting the system with white light (light in wide band wavelength), this operation is called: "Pumping the system". Once the population is inverted an applied electric field oscillating at the proper frequency causes a stimulated emission and the output is an amplified wave. The program illustrates the oscillation of an atom beteen two levels, under the applied electric field, this is known as a "Rabi oscillation". A hydrogenlike atom can be treated as a two level atom when dealing with the lower atomic levels, and applied field rotates at a frequency close to the natural frequency w0. This project uses FORTRAN and PGPLOT; the programs can be obtained by http from the Computational Physics http server. They are compiled with the command ``f77 atom.f -o atom.ex -lpgplot -lX11'' on the Technion Unix machines. (More information by email.)

Online material is avaliable for the Fall 1997

Computational Physics Class

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