Abstract

A new type of CO₂ ring laser has been developed incorporating a line selecting grating and an intracavity cell for non linear absorbing gases, as schematized in Fig. 1. Its continuous wave (cw) operation^[1] which can be set to a single line, and tunable over a single mode, shows unidirectional emission, selected by the Doppler effect on the gain medium gas flow with direction switching at line center. Full line tuning with unidirectional emission was also obtained with selection by the saturated absorption of SF₆ in the intracavity cell. Furthermore directional bistability was verified as due to the competition between the effects of saturated absorption in the cell and the Doppler shift on the flowing gain medium.^[1]

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