Figure 1

(a) Energy-level diagram of the four-level, double-$\Lambda$ system driven by three optical fields: driving ($B$ and $C$) and probe ($P$) beams in a four-wave mixing configuration giving rise to the signal beam ($S$). (b) Illustration of the proposed setup for an EIG with maximal coherence. Multiple slits are added to the $B$ and $C$ fields which are combined in a beam splitter with the probe field in a collinear configuration. The $z$ axis is parallel to the propagation direction. The probe and signal fields diffract along the transverse $x$ direction. (c) Intensity mask to be added to the driving fields consisting of multiple slits of width $w$ separated by $D$.Reuse & Permissions

Figure 2

Probe and signal wave amplitudes as a function of propagation distance (in units of the probe absorption length $z_0$) with driving fields on ($\Omega =0.5\gamma$) and off ($\Omega =0$). Field amplitudes are normalized such that, at the input, the probe amplitude is $E_p\left(0\right)=1$. We used ${\gamma }_0=0.001\gamma$.Reuse & Permissions

Figure 3

(a) Probe and (b) signal transmission functions plotted vs the transverse distance $x$ (in units of the grating period $D$) for $L=2z_0$ [dashed (red) line] and $L=10z_0$ [(solid (blue) line]. In regions of high transmission, the driving fields are on, and in regions of low transmission, the fields are off. The slit width was chosen to be $w=D/2$.Reuse & Permissions

Figure 4

Fraunhoffer diffraction patterns for the (a) probe and (b) signal waves. The intensity is normalized such that if $T_p\left(x\right)=1$, then $I_p(\theta =0)=1$.Reuse & Permissions