Highly scalable femtosecond coherent beam combining

Summary form only given. Coherent beam combining (CBC) [1] of fiber amplifiers provides an attractive mean of reaching simultaneously the high peak and high average powers required for various industrial, scientific and defense applications. By using this technique, the highest energy provided by an ultrafast fiber laser system was recently established [2]. For much higher energies, architecture has to be compatible with very large number of fibers [3]. Thus, the goal of the XCAN project is to overcome all the key scientific and technological barriers to the design and development of an experimental laser demonstrator with 61 fiber amplifiers coherently combined.Interferometric phase measurement has proven to be particularly well suited to phase-lock a very large number of fibers in continuous regime [4,5]. A small fraction of the N beamlets in a tiled-aperture configuration is imaged onto a camera. The beamlets interfere independently with a reference beam. The phase mismatch of each beam with the reference is then calculated from the interferences' position. With this technique, we demonstrate the coherent combination of 19 femtosecond pulses in passive fiber architecture.