Spectral shaping of an ultrafast ytterbium fiber laser via a passive intracavity optical filter: a simple and reliable route to sub-45  fs pulses

Abstract

We investigate the use of passive intracavity optical filters for controlling the laser output spectrum of a polarization-mode-locked, ultrafast ytterbium fiber laser. The overall lasing bandwidth is increased or extended by strategic choice of the filter cutoff frequency. Overall laser performance, including pulse compression and intensity noise, is investigated for both shortpass and longpass filters with a range of cutoff frequencies. The intracavity filter not only shapes the output spectra, but also provides a route for overall broader bandwidths and shorter pulses in ytterbium fiber lasers. These results demonstrate that spectral shaping with a passive filter is a useful tool to routinely achieve sub-45 fs pulse durations in ytterbium fiber lasers.

Methods Controlling Radiation Parameters of Mode-Locked All-Fiberized Lasers

“…The drawback of this method is that it is not compatible with the "all-fibre" format. For the same reason and because electrical control is not possible, passive radiation intensity filters are rarely used [76]. Spectral filters with variable transmission bandwidth may have fibre-optical input and output [77], and also may be electrically driven [78], but they are used infrequently in their simple configurations (as a free-space component without electrical control [79]).…”