Electromagnetically induced phase grating controlled by spontaneous emission

<p id="sp0005">Electromagnetically induced phase grating controlled by spontaneous emission is studied. The results show that the diffraction efficiency of phase grating is strikingly enhanced due to the existence of spontaneously generated coherence (SGC), and the diffraction efficiency of 35% can be obtained in optimal SGC parameter case. Furthermore, at large SGC parameter, the high efficiency of phase grating can be maintained by the application of weak coupled and relatively strong probe fields, and choosing the proper length of atomic sample. At the same time, in such an atomic system, the SGC effect depends on incoherent pump.