title: Nanosecond vortex laser pulses with millijoule pulse energies from a Yb-doped double-clad fiber power amplifier.
abstract: Nanosecond vortex pulses were generated using a stressed, large-mode-area, Yb-doped, fiber amplifier with an off-axis coupling technique for the first time. A pulse energy of 0.83 mJ (corresponding to a peak power of 59 kW) was achieved at a pump power of 25.7 W. The optical-optical efficiency was measured to be 31%. The millijoule nanosecond vortex pulses will be potentially applied to novel material processing, such as metal microneedle fabrication.
authors.affiliation: Graduate School of Advanced Integration Science, Chiba University,1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
authors.forename: Mio
authors.initials: M
authors.lastname: Koyama
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hirose
authors.forename: Masahito
authors.initials: M
authors.lastname: Okida
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Takashige
authors.initials: T
authors.lastname: Omatsu