Characteristics of a visible modulation instability fiber laser

Cross-phase modulation has been harnessed to construct a modulation instability laser operating at 514.5 nm. The laser output consists of orthogonally polarized upshifted and downshifted sideband pulses separated in wavelength by 2.1 nm from the pump. The laser configuration has been found to generate a much more stable source of terahertz modulated light pulses than the single-pass configuration previously used to demonstrate modulation instability in the visible. The extra stability arises from the feedback, which provides a seed for the modulation, and hence a reduction in the pump power necessary compared with the single-pass configuration, which in turn reduces the Raman gain, and the asymmetry of the sideband amplitudes. The sideband pulses can be combined to generate a modulated envelope of 4-THz oscillations with a duration of 10-15 ps