Coherent combining of large-aperture high-energy Nd:glass laser amplifiers

We present coherent beam combining of nanosecond pulses with 20-J energy and large beams using a Sagnac interferometer geometry based on Nd:glass rod-type amplifiers. In this study, we demonstrate that coherent beam combining is compatible with large-diameter energetic beams, presenting, therefore, an interesting and solid perspective towards the performance improvement of large-scale laser facilities, especially in terms of high-repetition-rate and high-energy operation. We demonstrate that for energy of 20 J, the coherent combination efficiency is around 92%, with high beam quality and long-term stability. A thorough temporal and spatial characterization of the system’s operation is provided to forecast the various potentialities available for large-scale facilities.