Fig. 1. (a) Energy level scheme of the ⁸⁷Rb D₁ transition and the transitions of the probe and the control. (b) Time sequence of the experiment. (c) Experimental setup. A probe pulse is reflected from a computer-controlled SLM with modulation into the desired modes. A 4f system images the SLM plane to the center of the Rb cell. Two PBSs can combine and separate the control and the probe beams. Another 4f system is used afterward to image the retrieved beam onto the ICCD camera. Before the beam enters the ICCD, an atomic filter is used to filter the remaining control beam.

Fig. 2. Storing eIG_10,2,2 and IG_10,2,2 beams. Elegant beams with even modes are shown in row (a) and odd modes in row (c). Row (b) and row (d) correspond to the standard even and odd IG beams, respectively. Column (1), theoretical simulations of the original patterns. Column (2), images obtained experimentally before storage. Columns (3)–(5), images obtained after being stored for different time intervals 1 µs, 2 µs, and 3 µs, respectively.

Fig. 3. Storing eIG_20,4,2^e mode [row (a)] and eIG_20,4,2^o mode [row (b)]. Same as Fig. 2, columns (1) and (2) are theoretical simulations and experimentally obtained images before storage, and columns (3)–(6) are retrieved results with storage time increasing from 1 µs to 4 µs.

Fig. 4. Storing eIG_20,4,ε^e modes with ε being 0, 0.5, 1, 2, 3, 4, and 200 [column (1) to column (7)]. Row (a) shows obtained images before storage. Row (b) shows retrieved modes after a storage time of 3 µs.

Fig. 5. Pearson correlated coefficient (PCC) values of the even eIG_10,2,2 modes (with solid circles), the even IG_10,2,2 modes (with hollow circles), the odd eIG_10,2,2 modes (with solid squares), the odd IG_10,2,2 modes (with hollow squares), the even eIG_20,4,2 modes (with triangles), and the odd eIG_20,4,2 modes (with inverse triangles) with storage times increasing from 1 µs to 3 µs.

Fig. 6. Schematic diagrams illustrating the principle of the anti-diffusion mechanism of the eIG mode. Intensity distributions of the eIG and the IG modes in the spatial domain before storage [column (1)] and after storage [column (4)], and distributions in the frequency domain before storage [column (2)] and after storage, which is Gaussian filtered [column (3)]. Row (a) eIG_10,2,2^e. Row (b) IG_10,2,2^e. Row (c) eIG_10,2,2^o. Row (d) IG_10,2,2^o.