Gain-Managed Nonlinear Amplifier:

Details of pulse evolution shown in the amination:

The animation shows pulse evolution in 4 meters of 10 μm core double-clad (Nufern PLMA-YDF-10/125-VIII) gain fiber. The seed pulse is 1 nJ, and 0.8 ps transform-limited Gaussian with a repletion rate of 50 MHz. The gain fiber is cladding co-pumped with 12 Watt at 976 nm. 

GMN amplifier Design:

In the GMN amplification regime, the nonlinear spectral broadening is balanced by strong, longitudinally evolving gain-shaping. In contrast with conventional ultrafast amplifiers, in which the gain is assumed to be static, in the GMN regime, the gain spectrum’s evolution plays an important role. Typically, GMN amplifiers require normal dispersion and longitudinal evolution of spectral gain profile. Practically, GMN amplifiers are implemented with cladding-pumped YDF in co-pumping configuration and require several propagation meters to evolve to the gain-managed regime. The practical limitation of the achievable pulse energy is stimulated Raman scattering. The amplified pulse duration is typically equal to several ps, and the pulse can be compressed with a grating pair close to a transform-limited duration. 

Related Papers:

1. P. Sidorenko, W. Fu, and F. Wise. “Nonlinear ultrafast fiber amplifiers beyond the gain-narrowing limit.” Optica 6, 1328 (2019).

2. P. Sidorenko and F. Wise, “Generation of 1  µJ and 40  fs pulses from a large mode area gain-managed nonlinear amplifier,” Opt. Lett. 45, 4084-4087 (2020)