Two-dimensional gain cross-grating based on spatial modulation of active Raman gain

Wang Li^{1, 2}, Zhou Feng-Xue¹, Guo Hong-Ju³, Niu Yue-Ping¹, Gong Shang-Qing^{1, †,}

(a) Schematic diagram of the four-level N-type atomic system. The possible levels correspond to the hyperfine levels of ⁸⁵Rb atoms: |⁵S_1/2, F = 3, m = −3〉 = |1〉, |⁵S_1/2, F = 2, m = −1〉 = |2〉, |⁵P_1/2, F = 2, m = −2〉 = |3〉, and |⁵P_3/2, F = 1, m = 0〉 = |4〉. (b) Sketch of a prototype.