Lab #7 Lasers

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Lasers simulation from PhET

Conceptual goal: Develop a basic understanding of the relationship between energy levels in an atom and how lasers work.
Experimental goal: Use of a spectrometer to record intensity vs. wavelength. Relate results to an energy level diagram.

Both Physics and EE students should understand the basic operation of Lasers since they are widely used in research and industry. Students will discover the requirements for building a laser while following this tutorial and exploring the associated PhET simulation. We have extended the tutorial developed at UC-Boulder to include rate equations and Einstein coefficients.

In the experimental portion of this laboratory students will use spectrometers to record the spectra of the side (non-lasing) light of a clear-case HeNe laser. Students will analyze the photon counts for different wavelengths and develop an energy level diagram that includes the different electronic transitions involved.

Sample Results:



The PhET activity, "How to Make a Laser," developed by Sam McKagan, Kathy Perkins, and Carl Wieman, can be found here. If you want to use the modified version of this activity in your own course, please contact mlpuerto at

This material is based upon work supported by the National Science Foundation under Grant Number DUE-1140034.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.