INSTABILITY IN A CO2 SEQUENCE-BAND LASER WITH A SATURABLE ABSORBER AND VIBRATION-TO-VIBRATION ENERGY-TRANSFER PROCESSES

Several types of instability are observed in the passive Q-switching (PQS) pulsation of a CO2 sequence-band laser with a saturable absorber. The observed pulse shapes are different from those of a regular-band CO2 laser in detailed structure. We propose a novel model for the PQS instability of a CO2 sequence-band laser by considering two vibration-to-vibration energy-transfer processes. We find that the sequence-band PQS pulse width critically depends on the rate of vibrational relaxation in the nu3 mode. The vibration-to-vibration relaxation rate is estimated from the analysis of the pulse shapes.