All-fiberized very-large-mode-area Yb-doped fiber based high-peak-power narrow-linewidth nanosecond amplifier with tunable pulse width and repetition rate*

Abstract

We demonstrate an all-fiberized narrow-linewidth nanosecond amplifier with high peak power, tunable pulse width, and repetition rate. A fiber-coupled narrow-linewidth laser diode operating at 1064.1 nm is employed as the seed source, which is gain-switched to generate nanosecond pulses with tunable pulse widths of 1–200 ns and tunable repetition rates of 10 Hz–100 kHz. By utilizing a very-large-mode-area Yb-doped fiber with a core diameter of 50 μm in the power amplifier, thresholds of the stimulated Brillouin scattering at different pulse widths and repetition rates are increased. The maximum average power reaches 30.8 W at the pulse width of 4 ns and a repetition rate of 100 kHz, corresponding to an optical-to-optical conversion efficiency of ∼55.2%. Pulse energy and peak power are calculated to be 0.2 mJ and 50 kW, respectively, which are limited by stimulated Brillouin scattering. The 3-dB spectral linewidth remains around 0.05 nm during the power scaling process. The stimulated Brillouin scattering limited output powers at different pulse widths and repetition rates are investigated. Peak power of 47.5 kW (0.19 mJ) is obtained for the 4 ns pulses at a repetition rate of 50 kHz, which is nearly the same as that of 4 ns pulses at 100 kHz. When the pulse width of the seed source is increased to 8 ns, peak powers/pulse energies are decreased to 19.6 kW/0.11 mJ and 13.3 kW/0.08 mJ at repetition rates of 50 kHz and 100 kHz, respectively.

The 266-nm ultraviolet-beam generation of all-fiberized super-large-mode-area narrow-linewidth nanosecond amplifier with tunable pulse width and repetition rate

“…The basic narrow-linewidth fiber amplifier architecture followed our previous work. [29] When the pulse duration and the repetition frequency of the laser amplifier system were set to be 4 ns and 100 kHz, respectively, the laser amplifier delivered 13.8-W average power corresponding to the pulse energy of 138 µJ centered at 1064.1 nm as shown in Fig. 2.…”

Hundred-watt level all-fiber visible supercontinuum generation from a graded-index multimode fiber

“…The maximum SC output power is boosted from 102 W to 204 W and 362 W, when varying the pulse duration from 1 ns up to 3 ns and 6 ns, respectively. This is because a long pulse can extract more energy from the pump, resulting in the increase of the main-amplifier output power and then the SC output power [24] . The final SC output spectra of different pulse durations are shown in Fig.…”