“…Interest in ring lasers developed almost simultaneously with the invention of laser itself [1,2,3,4,5]. Intensive work on this device has been motivated both by fundamental aspects (especially in the field of non linear dynamics, phase transitions, instabilities and chaos [6,7,8,9,10,11,12,13,14,15]) and by practical applications (amongst which are the ring laser gyroscope [16,17,18] and the single-frequency unidirectional ring laser [19,20,21]). The recent achievement of active beat note stabilization in a diode-pumped Nd-YAG ring laser [22] revived interest for homogeneously broadened (e.g.…”