In this paper, we propose an optimized design of the picosecond MOPA fiber laser by using hybrid-doped Yb fibers. The
detailed implementation is that high-doped gain fiber with relatively small fiber core is adopted in the low-power
pre-amplifiers, thus the shortest fiber could be ensured and the thermal load is not so heavy. In the power amplifier stage,
the normal-doped large mode area gain fiber is utilized, then the thermal effects can be minimized and the output beam
quality could be ensured. The design simultaneously takes into consider the output beam quality, thermal load, nonlinear
phase shift, pulse peak power of the picosecond fiber laser. With using the existed Yb-doped fibers, we demonstrate a
high-power picosecond MOPA fiber laser with the proposed method. The average output power is up to 110 W, the total
optical conversion efficiency is 63.2%. No stimulated Raman scattering, amplified spontaneous emission and residual
pump light are observed in the output spectrum. The - 6 dB bandwidth of the output spectrum at the full output power is
~ 4 nm.
Photonic crystal fiber has been widely used in visible and near-infrared
supercontinuum generation due to its flexible dispersion control and high nonlinearity.
However, the maximum average output power of supercontinuum from a photonic crystal
fiber has not exceed one hundred watt owing to the small core diameter of the photonic
crystal fiber and the low coupling efficiency between the pump and the photonic crystal fiber.
Recently, supercontinuum generation directly from a nonlinear fiber amplifier attracts lots of
attention as a result of its simple structure and low splicing loss and many excellent results
have been achieved either in low and high average power, which is proved to be a promising
method to realize kilowatt level high power near-infrared supercontinuum. However, the
numerical study on high power near-infrared supercontinuum generation from a nonlinear
fiber amplifier has been rarely reported, so there is great necessity to carry out some
theoretical study on it. In this paper the complex Ginzburg-Landau equation is used to
describe the formation and propagation of high power near-infrared supercontinuum
generation in a nonlinear fiber amplifier. The chromatic dispersion of the ytterbium-doped
fiber is measured by a Mach-Zehnder interferometer. The roles of the small signal gain, input
pulse width and initial chirp of the input pulse played on the continuum formation are
analyzed in detail. The results are in good agreement with the experiments which can provide
some theoretical guidance on future optimization of the flatness and width of the
supercontinuum generation from a nonlinear fiber amplifier.