Raman effective Rabi frequency ($|{\Omega }_{\mathrm{eff}}|=|{\Omega }_1{\Omega }_2|/(2|\Delta |)$)

Eliminating a common far-detuned intermediate state with single-photon couplings $\hslash {\Omega }_1/2$ and $\hslash {\Omega }_2/2$ gives effective Rabi angular frequency of magnitude $|{\Omega }_1{\Omega }_2|/(2|\Delta |)$. The complex laser phases set the coupling phase, and differential AC Stark shifts change the two-photon resonance.