Theoretical output probe gain G_p as a function of the two-photon detuning δ/γ and the probe-pump angle θ with (a) a single pump field and (b) two pump fields. The area intersecting the dashed line is the area selected by our experimental parameters. The angle between pump fields P₁ and P₂ is θ₀/2 = 0.615°. The angles between the probe field and the pump fields P₁ and P₂ are θ₁ = θ₂ = θ = 0.861°.