title: 240 W high-average-power square-shaped nanosecond all-fiber-integrated laser with near diffraction-limited beam quality.
abstract: We report an all-fiber-integrated high-average-power square-shaped nanosecond pulse laser operating at 1068 nm based on the master oscillator power amplifier configuration. The seed source is a passively mode-locked Yb-doped fiber laser with fundamental cavity repetition rate of 1.86 MHz. Output pulses with a square shape can be tuned in pulse width from 271 ps to the nanosecond level. The average output power reaches to 9.21 W after three preamplifiers. Finally, a main amplifier is developed to boost the average output power to 240 W, and the corresponding pulse energy and peak power are ∼ 129.3 μJ and 36 kW, respectively. The efficiency of the main amplifier is ∼ 61.3%, and the beam quality represented by M(2) factors is below 1.3 and 1.2 in the X and Y directions.
authors.forename: Hailong
authors.initials: H
authors.lastname: Yu
authors.forename: Rumao
authors.initials: R
authors.lastname: Tao
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wang
authors.forename: Pu
authors.initials: P
authors.lastname: Zhou
authors.forename: Jinbao
authors.initials: J
authors.lastname: Chen
mesh_terms: D000669:Amplifiers, Electronic; D004735:Energy Transfer; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D007834:Lasers; D009991:Oscillometry / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*; D018511:Systems Integration