Manipulation of the Raman process via incoherent pump, tunable intensity, and phase control

We present a proposal to manipulate the Raman process via incoherent pump, tunable intensity, and phase control of the driving fields. It is found that Raman absorptive peaks can become Raman gain peaks by controlling the incoherent pump, and this property leads to the group velocity of a weak probe pulse from subluminal to superluminal with less absorption or gain. Furthermore, it is also shown that Raman gain peaks can be controlled not only by controlling the intensities of the driving fields but also by adjusting phases of the driving fields, and this leads to the strong negative dispersion with less gain.