Also known as the "Acoustic Waveguide", this experiment is designed to introduce the physics of dispersive pulse propagation, and propagation in waveguides -- a good prototype for light propagating in optical . A set of speakers drives sound pulses down different modes of an acoustic waveguide, and the student studies what the system (differential equation plus boundary conditions) imposes on the pulses.
(The experiment is currently located in MP246; last write-up revision: September 2004.)
Some additional resources:
This experiment is part of the Photonics/Optics Teaching Laboratory at the Department of Physics, UniversityToronto
Here is the experiment setup, showing the 6 metre long waveguide, and the computer which runs the speakers and microphones.
Here is the view down the waveguide.
This plot of pulse intensity versus frequency (vertical axis) and time (horizontal axis) shows the affects of dispersion on the pulse. Data taken by Kevin Hurley on January 31, 2006.
Another beautiful chirp plot: intensity at each frequency and time (both arbitrary units) show delay increasing as frequency approaches the cutoff. Data taken by Benjamin Leung, March 2006.
Last updated on 10 January 2011