title: High power, compact, picosecond MOPA based on single trench fiber with single polarized diffraction-limited output.
abstract: We experimentally demonstrate an all-solid Yb-doped 30 μm core diameter single trench fiber. Measurements ensure a robust effective single-mode operation without the need of tight coiling as required for conventional fibers thanks to the ultralow NA (∼0.038) and resonant ring surrounding the core. All-solid and cylindrical design ensures the suitability for mass scale production with the added benefit of all-fiberized device structure. A compact master oscillator power amplifier (MOPA) has been built using this fiber delivering ∼23.5  ps pulses at 13.5 MHz repetition rate delivering up to ∼52  W of average output power corresponding to a pulse energy of ∼3.8  μJ and peak power of >160  kW, while maintaining ∼76% slope efficiency. The output beam exhibits a polarization extinction ratio of more than 15 dB and a M2 less than 1.15.
authors.forename: D
authors.initials: D
authors.lastname: Jain
authors.forename: S
authors.initials: S
authors.lastname: Alam
authors.forename: C
authors.initials: C
authors.lastname: Codemard
authors.forename: Y
authors.initials: Y
authors.lastname: Jung
authors.forename: M N
authors.initials: MN
authors.lastname: Zervas
authors.forename: J K
authors.initials: JK
authors.lastname: Sahu