Limits in CW injection-locking of stable resonator CO2 TEA lasers

The performances of CW injection-locking of CO₂ TEA lasers at line center and at ～600 MHz off line center are compared experimentally. Heterodyning of the injection frequency permits one to measure accurately the locking bandwidth as a function of the injected intensity. The minimum intensities needed to obtain reproducible frequency-looking were found to be 0.5 μW/cm² and 0.2 mW/cm² respectively. An analytical approach is described for predicting the tunability of injection-locked stable resonator CO₂ TEA lasers.