Suppression of thermal lensing effects in intra-cavity coherent combining of lasers

An efficient approach to suppress thermal lensing, when coherently combining several laser distributions, is presented. It is based on incorporating a compensating lens inside the laser cavity. The results reveal that with compensation the overall efficiencies can be more than 80% when combining four laser distributions and more than 90% when combining two laser distributions even at relatively high pulse repetition rates. A model for analyzing coherent combining is developed, where predicted results are in good agreement with the experimental results.