Pulse mode operation of a phase coupled CO2 waveguide lasers array

Phase coupled of CO2 waveguide lasers array by intracavity spatial filtering has been already reported in Ref. 1 in cw mode. The theoretical analysis for such a configuration gives a coupling efficiency larger than 70%,2 whereas the experimental measurements have been found as poor as 10%. The results discrepancy seems to be the consequence of the thermal loading of the optical elements set inside the laser cavity in which the light intensity is very large. By using a three mirrors cavity, it has been possible to reduce the power level on the optical elements resulting in an improvement of the coupling efficiency up to 66%.