MODE LOCKING OF THE CO2 LASER BY INTRACAVITY PHASE MODULATION

Abstract
Stable mode locking of a CO2 laser has been obtained with the use of a resonated internal electro‐optic phase modulator driven at frequencies near the axial‐mode interval. Pulses of 25‐nsec duration and 147‐nsec period were observed. Pulse trains at twice the fundamental mode frequency were also obtained. Stable locking was achieved with an rf input power to the modulator of less than 1 mW. Locking could be induced when the modulation frequency was within ± 130 kHz of the fundamental axial‐mode frequency.