1.5 MW peak power diffraction limited monolithic Yb-doped tapered fiber amplifier

High peak power lasers are of great importance for a wide number of applications like material processing, remote sensing and etc. The most impressive, and still record, result has been demonstrated with using of photonics crystal fibers (PCFs), where amplification to more than 1 MW peak power directly from amplifier was demonstrated [1, 2]. However such fiber are difficult in production, handling and requires use of bulk optics, that negates the benefits of truly all-fiber systems. For this reason, the development of alternative LMA design is still very actual task. One of the promising one is the tapered step-index fiber [3, 4]. Such fibers have robust single-mode (SM) input end part (to couple signal) and a very big core and outer diameters output end part. The output signal end is formally highly multi-mode, but slowly increasing diameter along the tapered fiber, ensuring of adiabatic enlargement of fundamental mode and suppress excitation of high order modes. A larger first cladding diameter at the output tapered fiber end makes possible counter-pumping using a low-brightness cheap pump diodes. Recently we have demonstrated chirped pulse amplification system, with final cascade based on Yb-doped PM fiber, generating diffraction limited (M²<;1.2) 5-ps pulses at 1057-nm with 0.5 MW of peak power and 7-ps pulses at 1035-nm with 100 kW of peak power, which were compressed down to 130-fs with 60% efficiency [4].