Showing papers on "Electromagnetically induced grating published in 2021"

Azimuthal modulation of electromagnetically induced grating using structured light.

Abstract: We propose a theoretical scheme for creating a two-dimensional Electromagnetically Induced Grating in a three-level $$\Lambda $$ -type atomic system interacting with a weak probe field and two simultaneous position-dependent coupling fields—a two dimensional standing wave and an optical vortex beam. Upon derivation of the Maxwell wave equation, describing the dynamic response of the probe light in the atomic medium, we perform numerical calculations of the amplitude, phase modulations and Fraunhofer diffraction pattern of the probe field under different system parameters. We show that due to the azimuthal modulation of the Laguerre–Gaussian field, a two-dimensional asymmetric grating is observed, giving an increase of the zeroth and high orders of diffraction, thus transferring the probe energy to the high orders of direction. The asymmetry is especially seen in the case of combining a resonant probe with an off-resonant standing wave coupling and optical vortex fields. Unlike in previously reported asymmetric diffraction gratings for PT symmetric structures, the parity time symmetric structure is not necessary for the asymmetric diffraction grating presented here. The asymmetry is due to the constructive and destructive interference between the amplitude and phase modulations of the grating system, resulting in complete blocking of the diffracted photons at negative or positive angles, due to the coupling of the vortex beam. A detailed analysis of the probe field energy transfer to different orders of diffraction in the case of off-resonant standing wave coupling field proves the possibility of direct control over the performance of the grating.

Effects of giant Kerr and quintic nonlinearities on electromagnetically induced grating in multiple quantum wells

Abstract: The characteristics of an electromagnetically induced grating (EIG) created in symmetric multiple quantum wells in the regime of electromagnetically induced transparency have been presented. The EIG is created due to absorption and phase modulation under the electromagnetically induced transparency. The increasing value of the Rabi frequency of control standing wave enhances transmission through the EIG. In addition, it is found that the diffraction efficiency of the grating and the intensity of the first-order diffraction can be controlled by controlling the Rabi frequency of the standing wave control field and the interaction length in the quantum well. Optical nonlinearities can improve the diffraction intensity of significant orders, particularly zeroth and first order. The improvement is largest in case only the Kerr is the dominant nonlinearity and moderate under quintic nonlinearity. Present results may be useful in communication and signal processing.

Phase and amplitude control of atomic grating in a three level closed lambda System

Abstract: We have theoretically studied the electromagnetically induced grating (EIG) in a three-level \textbf{closed $\Lambda$-type atomic system}. The upper level is coupled to the two lower levels via a strong control and a weak probe \textbf{field}. In addition to these two optical fields a weak microwave field is also applied to couple the lower two levels. Our results show that the relative phase of the three fields \textbf{in the} presence of microwave field enhances the dispersion in the medium and consequently provides control over magnitude of the diffraction intensities. We \textbf{have optimized} the system parameters such as \textbf{strength of the fields} and interaction length to attain increased first order diffraction. Furthermore, we have also studied the effects of probe detuning on diffraction intensities. Interestingly, the probe detuning results in suppression of the zeroth order intensity while increasing the higher order intensities.

Electromagnetically induced grating in a 3-level symmetric quantum well

Abstract: We propose a scheme of electromagnetically induced grating in 3-level symmetric quantum wells. Based on electromagnetically induced transparency, we obtain the intensity distribution of the Fraunhofer diffraction pattern of the probe field that is governed by a control field. The distribution of the intensity of the diffraction pattern of the grating can be controlled by controlling the Rabi-frequency of the control field, and the interaction length of the QW. Our results could be potentially used in semiconductor quantum well based photonic devices.