The self-pulsing laser oscillator

The self-pulsing laser oscillator is examined theoretically by developing a simple model based on the assumption that the pulse in the laser cavity is a 180° pulse for the medium. The concept of an optical 180° pulse is closely analogous to the idea of a 180° RF pulse discussed in spin-echo studies. The range of parameters for which a laser oscillator is expected to be self-pulsing is found from this theory, and the results are compared with experimental observations of the behavior of a 6328 Å He-Ne laser oscillator. Observations of self-pulsing are made as a function of cavity length, position of the gain medium in the laser cavity, and laser excitation. Observations of pulse widths and output frequency spectra are also reported. It is found that the main features of the experimental observations agree well with the theoretical predictions.