Teaching Physics with 670-nm Diode Lasers -- Experiments with Fabry-perot Cavities

In a previous paper we described details of the construction of stabilized 670-nm diode lasers for use in undergraduate physics laboratories. We report here a series of experiments that can be performed using the 670-nm diode laser, a homemade scanning Fabry-Perot cavity, a helium-neon laser, a simple photodiode, and a few pieces of electronics hardware. The experiments include: 1) an introduction to the scanning confocal Fabry-Perot cavity, and to its use as an optical spectrum analyzer; 2) laser frequency modulation and observation of FM sidebands using the optical spectrum analyzer; and 3) the Pound-Drever method for servo-locking a Fabry-Perot cavity to a laser. These experiments are relatively easy to set up and perform, yet they demonstrate a number of useful optical principles and experimental techniques.