Abstract A new theoretical scheme for two-dimensional (2D) electromagnetically induced grating (EIG) is proposed in a three-level Ξ-type atomic system. The system is driven by a weak probe field and two position-dependent coupling fields—a 2D standing-wave field and a vortex field. Due to lopsided spatial modulation of the vortex Laguerre–Gaussian field, the weak probe light could be diffracted into different domains and asymmetric 2D EIG is formed. The result shows that the diffraction patterns and efficiency could be effectively modulated by the azimuthal parameter of the vortex field. Also, the system parameters such as the probe field detuning, the intensity of the vortex field, and the interaction length could be used to regulate the diffraction properties of the 2D EIG effectively. The scheme of asymmetric 2D EIG may have some potential application in all-optical information processing and the design of quantum devices.
Abstract A new theoretical scheme for two-dimensional (2D) electromagnetically induced grating (EIG) is proposed in a three-level Ξ-type atomic system. The system is driven by a weak probe field and two position-dependent coupling fields—a 2D standing-wave field and a vortex field. Due to lopsided spatial modulation of the vortex Laguerre–Gaussian field, the weak probe light could be diffracted into different domains and asymmetric 2D EIG is formed. The result shows that the diffraction patterns and efficiency could be effectively modulated by the azimuthal parameter of the vortex field. Also, the system parameters such as the probe field detuning, the intensity of the vortex field, and the interaction length could be used to regulate the diffraction properties of the 2D EIG effectively. The scheme of asymmetric 2D EIG may have some potential application in all-optical information processing and the design of quantum devices.
Abstract We propose a theoretical scheme to realize a 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 an asymmetric 2D electromagnetically induced grating 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. This asymmetric 2D diffraction grating scheme may provide a versatile platform for designing quantum devices that require asymmetric light transmission.
Abstract A two-dimensional (2D) asymmetric diffraction grating controlled by vortex light in a double-Λ-type atomic system is studied. Such an atomic system is driven by a weak traveling-wave probe field and a signal field, a position-dependent strong standing-wave (SW) control field, and a Laguerre–Gaussian (LG) vortex field. Due to the asymmetric properties of the LG vortex field, the probe photons can be asymmetrically diffracted into four different domains after passing through the atomic media. The Diffraction patterns and intensities of the 2D asymmetric diffraction grating can be manipulated by the detuning of the probe field, the interaction length, and the intensity of SW control field. In addition, the relative phase and the azimuth parameter which is closely related to the vortex light also can be used to regulate the asymmetric diffraction grating effectively. This work may provide useful reference for optical information processing, especially for the design of optical beam dividers with desired intensities and novel quantum devices requiring asymmetric optical transmission.
Abstract We present a theoretical scheme to realize two-dimensional (2D) asymmetric diffraction grating in a five-level inverted Y-type asymmetric double semiconductor quantum wells (SQWs) structure with resonant tunneling. The SQW structure interacts with a weak probe laser field, a spatially independent 2D standing-wave (SW) field, and a Laguerre–Gaussian (LG) vortex field, respectively. The results indicate that the diffraction patterns are highly sensitive to amplitude modulation and phase modulation. Because of the existence of vortex light, it is possible to realize asymmetric high-order diffraction in the SQW structure, and then a 2D asymmetric grating is established. By adjusting the detunings of the probe field, vortex field, and SW field, as well as the interaction length, diffraction intensity, and direction of the 2D asymmetric electromagnetically induced grating (EIG) can be controlled effectively. In addition, the number of orbital angular momenta (OAM) and beam waist parameter can be used to modulate the diffraction intensity and energy transfer of the probe light in different regions. High-order diffraction intensity is enhanced and high-efficiency 2D asymmetric diffraction grating with different diffraction patterns is obtained in the scheme. Such 2D asymmetric diffraction grating may be beneficial to the research of optical communication and innovative semiconductor quantum devices.
We propose a theoretical scheme for creating a two-dimensional Electromagnetically Induced Grating in a three-level [Formula: see text]-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.
Abstract We propose a theoretical scheme for realizing a two-dimensional (2D) asymmetric diffraction grating in a four-level quantum dot molecules (QDMs) system with double tunneling effects. The QDMs system interacts with a weak probe field, a 2D SW control field and a composite Laguerre–Gaussian (LG) vortex field. By adjusting system parameters such as the orbital angular momentum (OAM) number, the beam waist parameter of the vortex light, the tunneling strength, and the detuning of the standing-wave (SW) field, the energy distribution and the diffraction intensity of the probe field can be controlled effectively. In addition, the detuning of the probe field can be used to achieve the symmetrical switching control of the 2D diffraction grating between the second and the fourth quadrants. This investigation may have potential application in beam splitting technology and optical device design.
Abstract We proposed a theoretical scheme for two-dimensional (2D) electromagnetically induced grating (EIG) in a closed-loop four-level atomic system driven by a weak probe field, a traveling-wave control field, two orthogonal standing-wave fields and a microwave field. Due to low amplitude modulation accompanied with large phase modulation, EIG can be obtained and the probe energy can be diffracted into first-order and even high-order directions with high efficiency. The results show that the diffraction pattern and efficiency of the EIG could be adjusted effectively by the probe field detuning, the coherent field intensity, the interaction length. Meanwhile, the quantum interference between the amplitude modulation and phase modulation can be manipulated by the relative phase, which can be used to regulate the diffraction pattern and efficiency of the 2D EIG. Our scheme of 2D EIG may be useful in beam splitting and all-optical switching.