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