Abstract

It is well known that when the frequency difference between two laser modes is small, as a result of nonlinear interaction, the frequencies of these two modes will lock together spontaneously. This phenomenon was called laser modelocking. A characteristic of traditional laser modelocking is that without mode interaction, each mode involved can be considered as in its steady state; namely, both its amplitude and phase are constant with time. However, under certain, conditions a laser can also operate in a chaotic state, and in this state both the amplitude and phase of the laser modes vary with time. It is still possible that two chaotically emitting laser modes spontaneously lock together? To explore the possibility of chaotic laser modelocking, we have conducted experiments to study the nonlinear mode interaction between two chaotic laser modes. Our experimental setup used an optically pumped bidirectional NH₃ ring laser operating in the wavelength of 153 μm. It was shown previously that under suitable conditions both of the forward and backward modes of the laser can operate chaotically. Use of a bidirectional ring laser has the advantage that the individual interacting modes easily can be detected separately at the same time.

© 1996 Optical Society of America