Physical Review A
Rabi resonance in frequency conversion by four-wave mixing in lasers and its connection with the multimode laser instability
F. Castelli, L. A. Lugiato, R. Pirovano
Abstract
We analyze the behavior of a laser upon injection of a weak-field resonant with a cavity mode adjacent to the lasing mode; the four-wave-mixing coupling generates also a field with the frequency of the symmetrical adjacent mode. Using the Maxwell-Bloch equations, we show that under appropriate conditions there is a spectacular amount of frequency conversion, with a peak when the free spectral range is equal to the Rabi frequency of the laser field multiplied by \ensuremath{\surd}2 . The origin of this effect is identified with the help of the linear stability analysis of the free-running laser, which shows also the deep connections with the classical laser instability, predicted by Risken and Nummedal [J. Appl. Phys. 39, 4662 (1968)] and Graham and Haken [Z. Phys. 213, 420 (1968)]. The Rabi peak is a precursor of the multimode laser instability, but it arises for smaller values of the pump parameter and is only weakly sensitive to the transverse shape of the laser beam.