## 1 Introduction
The gain on the Stokes side is explained by a three-photon resonance between two manifolds in the dressed state picture from the lower state in the lower manifold to the upper state of the next highest manifold. The loss on the anti-Stokes side is the single photon resonant absorption between two adjacent manifolds also from the lower state to the upper state in the upper manifold. The opposite response would be expected for blue detuning of the pump, as the upper state would now have the initial population and so the transitions would be from the upper state to the lower state of the next highest manifold. Now if we consider the two-photon dressed states, each of the Raman levels would be split into two coherent states with a separation of \(\Omega^{\prime}\), the two-photon Rabi frequency because of strong laser pumping at the pump frequency \(\omega_{0}\) and the first Stokes frequency, \(\omega_{-1}\). A schematic of two manifolds in a two-photon dressed state picture is depicted in Figure 1.  
The manifolds are separated by the Raman frequency. In order to efficiently generate MRG orders, the pump beams need to be red-detuned to be resonant with the single-color Stark shifted transition. This red-detuning leads to the lower state of each manifold to be the initially populated state. From linear Raman scattering, each of the MRG orders, \(\omega_{\mathrm{j}}\), could either amplify a Stokes order \(\omega_{\mathrm{j}-1}\) as depicted in Figure 1a or could as shown in Figure 1c be amplified itself by the scattering of the anti-Stokes order \(\omega_{\mathrm{j+1}}\). Other resonant interactions are also possible. The system could be left in the higher coherent state and generate a photon at the frequency of \(\omega_{\mathrm{j-1}}-\Omega^{\prime}\) as shown in Figure 1b. This Rabi-shifted frequency can then experience gain through stimulated Raman scattering. On the other hand, the higher coherent state can also be reached as depicted in Figure 1d by absorption of the Rabi-shifted anti-Stokes frequency \(\omega_{\mathrm{j+1}}+\Omega^{\prime}\) with gain on the MRG order \(\omega_{\mathrm{j}}\). This would assume that  
Figure 1: Diagram showing linear Raman scattering from two-photon dressed states; (**a**) scattering of pump beam, \(\omega_{\mathrm{j}}\), to Stokes \(\omega_{\mathrm{j-1}}\); (**b**) scattering of pump beam, \(\omega_{\mathrm{j}}\), to Stark shifted Stokes \(\omega_{\mathrm{j-1}}-\Omega^{\prime}\); (**c**) gain of pump beam, \(\omega_{\mathrm{j}}\) by scattering of anti-Stokes beam \(\omega_{\mathrm{j+1}}\); (**d**) gain of pump beam, \(\omega_{\mathrm{j}}\) by scattering of Stark shifted anti-Stokes beam \(\omega_{\mathrm{j+1}}+\Omega^{\prime}\). there were frequencies present at \(\omega_{\rm j+1}+\Omega^{\prime}\), which could be there if a background continuum was generated. In our previous work, where we stretched the pulses to just 600 fs, there was a strong continuum under the Raman peaks and we observed red-shifted shoulders and dips in the continuum spectrum on the blue side of the Raman orders [7]. Linear Raman scattering of the continuum spectrum can cause gain on the red side of the MRG orders and absorption on the blue side. If the two pump beams were blue detuned from resonance, then the upper dressed state should be in the initially populated state and we would expect gain on the blue shifted side of the peaks and absorption on the red side.