Asymmetric 2D diffraction grating via vortex field in an inverted-Y-type atomic system

Abstract

We propose a theoretical scheme to realize two-dimensional (2D) diffraction grating in a four-level inverted-Y-type atomic system coupled by a standing-wave (SW) field and a Laguerre-Gaussian (LG) vortex field. Owing to asymmetric spatial modulation of the LG vortex field, the incident probe field can be lopsidedly diffracted into four domains and asymmetric 2D electromagnetically induced grating (EIG) is created. By adjusting the detunings of the probe field and the LG vortex field, the intensities of the LG vortex field and the coherent SW field, as well as the interaction length, the diffraction properties and efficiency can be effectively manipulated. In addition, the effect of the azimuthal parameter on the Fraunhofer diffraction of the probe field is also discussed. The scheme of symmetric 2D diffraction grating may provide a versatile platform for designing quantum devices that require asymmetric light ransmission.