Q-Switched Rod-Type Multicore Fibre Laser Delivering 3.1 mJ Pulses

Multicore fibres (MCFs) with active doped cores are a promising technology to increase effective mode area and therefore available power and energy of fibre amplifiers and lasers, most recently demonstrated in coherently combined systems [1] . With ns-class pulses, energies of up to 26 mJ have been extracted from advanced fibre designs in multi-stage amplifiers [2] . Self-focusing at peak powers of around 5 MW limits the maximum pulse energy extracted from a single fused silica core, but MCF lasers potentially enable continued scaling beyond these limitations by distributing energy over many cores. Modelling of rod-type MCFs show potential to achieve multi-kW average power and Joule-class combined pulses from a 1 m long fibre [3] . In this submission, a Q-switched 16-core rod-type Yb-doped MCF is demonstrated, which can directly seed further MCF amplification stages without the need for fibre arrays or beam-splitting optics.