Lossless Suppression and Enhancement of Soliton Self-Frequency Shifts

Soliton self-frequency shifts (SSFS) can be suppressed in optical fibers through spectral recoil, but this process leads to losses through continuous transfer of energy to a dispersive wave. We demonstrate a novel way to alter the strength of SSFS in photonic crystal fibers through a frequency-dependent nonlinear parameter $\gamma(\omega)$. Our numerical simulations show both suppression and enhancement of SSFS depending on the sign of nonlinear slope. A large enough positive value of this slope can lead to total suppression of SSFS, without spectral recoil and without energy transfer to a resonant dispersive wave. Numerical simulations are supported by mathematical predictions based on the moment method.