Abstract An electromagnetically induced grating in a four-level tripod-type atomic system is studied theoretically. By virtue of a weak standing-wave signal field, the phase modulation effectively diffracts a weak probe field into the first-order direction. By changing the weak signal field, the diffraction of the weak probe field can be modulated in real time, and a first-order diffraction efficiency of more than 32% can be obtained with proper parameters. Such a system has a potential application in an all-optical switch controlled by a weak optical signal.
Fund: Project supported by the National Natural Science Foundation of China (Grants Nos. 11004126 and 61275212), the Natural Science Foundation of Shanxi Province, China (Grant No. 2011021003-1), and the National Basic Research Program of China (Grant No. 2010CB923102).
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