Continuous Wave Diode Laser Seeding of Tunable Femtosecond Soliton Pulses

In the near infra red, frequency tunable,femtosecond pulses can be readily obtained using the soliton Raman generation process (1). This continuum consists of several solitons the number of which is not particularly controllable although it is dependent on the pump power. In addition, the spectral extent is not finely controllable and as such the soliton Raman continuum is of limited use as a practical source. It is possible however, to spectrally filter a region of interest to generate a wavelength selectable femtosecond soliton and this method has been used to give a practical source for pump-probe experiments (2), where the time jitter between consecutive solitons in the pulse train is unimportant. One problem with this method is that it is inefficient, since most of the generated radiation from the continuum is discarded.