Squeezing induced high-efficiency diffraction grating in two-level system.

We show the effect of squeezed vacuum on laser-induced grating in a weak standing-wave-driving two-level atomic system. Using the optical Bloch equation and the Floquet harmonic expansion, we obtain the linear response of the medium with respect to the probe field, which determines the transmission spectrum and diffraction intensity. At the presence of the squeezing, the grating with large intensity both in the first- and higher-order directions can be obtainable even though the driving is relatively weak. The responsible mechanism is due to squeezing-induced gain accompanied by the large dispersion. Based on the spatial gain and phase modulations, the first- and high-order diffraction intensities simultaneously could have the large values. Such a scheme we present could have potential applications in implementing lensless imaging and developing the photon devices in quantum information processing.