Search

This work models electromagnetically induced grating (EIG) in a metal nanoparticle (MNP)–double quantum dot (DQD) hybrid system considering the Coulomb effect to specify the scattering rates where the strong-coupling case is considered. This work does not take normalized values or values from different structures; it is of the material property by calculating the energy states of DQDs and their transition momenta. The wetting layer (WL) where quantum dots (QDs) are grown is taken in the calculations where both QD–QD and WL–QD transition momenta are considered, and the orthogonalized plane wave is considered for the last transitions. The screening effect is taken when modeling Rabi frequencies. Although complexity faces Coulomb problems in their modeling and computation, one gains the realization of scattering time under this many-body effect, which was not specified earlier. The transmission coefficient is reduced with the probe. Detuning the probe increases the transmission. Tunneling increases the transmission due to an overall increase in scattering rates. A small distance between the MNP–DQD increases the transmission, while a long distance reduces it, where the scattering rates are reduced. Increasing the MNP radius reduced the transmission. The detuning is more effective than other factors. The MNP inhibits the zeroth-order diffraction, while other orders are strengthened due to the modulation of the EIG behavior of the DQD structure by the MNP. The results indicate that the scattering rates control the processes in this system. [ABSTRACT FROM AUTHOR]

In this work, the external magnetic field is employed as a "knob" to transfer the light energy from the zero-order diffraction to the high-order diffractions of electromagnetically induced grating in a degenerate two-level atomic medium. Under a standing-wave coupling field, the diffraction of the probe beam is created with the diffraction pattern including zero-, first- and second-order diffractions. When the magnetic field is not applied, the absorption grating is formed based on amplitude modulation of the transmission function; most of the probe light energy is focused on the zero-order diffraction (about 70%) and only about 6% of the first-order diffraction. However, when the external magnetic field is applied, the phase grating is formed based on the phase modulation of transmission function; the probe light energy is transferred from zero-order diffraction to first- and second-order diffractions, in which the first-order diffraction efficiency can be obtained about 32% with proper magnetic field strength. Moreover, the probe light energy can also be transferred from zero-order diffraction to first- and second-order diffractions by adjusting the frequency and/or the intensity of the coupling and probe fields in the presence of external magnetic field. [ABSTRACT FROM AUTHOR]

The effect of Er 3 + ion concentration and incoherent pumping field on the Fraunhofer diffraction pattern of the transmitted light beam in Er 3 + : YAG crystal is discussed. It is shown that under different concentration of Er 3 + ion in crystal, the energy of the probe light can transfer to the higher orders of the grating. Also, it is shown that the switching from electromagnetically induced grating to electromagnetically induced phase gratin or vice versa can be obtained by different concentration of Er 3 + ion and incoherent pumping rate in crystal. Moreover, we have found that by replacing the probe light by optical vortex light, the asymmetric diffraction pattern can be obtained by tuning the optical vorticity of optical vortex light. In this case, the asymmetric diffraction pattern can also be controlled at different ion concentration. [ABSTRACT FROM AUTHOR]

We propose an atomic grating based on an electromagnetically induced transparency phenomenon that switches between zeroth-order diffraction to a distinct higher-order diffraction pattern by driving a planar gaseous medium of a four-level tripod ( ⋔) atoms with three laser beams: modulation of standing wave control beam propagating nearly perpendicular to the planar medium, while vortex and weak plane probe beams directed perpendicular to the medium. We numerically investigate the behavior of the amplitude, phase modulations, and probe field diffraction intensities of different orders by the variation of the field detunings and orbital angular momentum number of the composite vortex light beam. Specifically, in the off-resonant case, the interplay between a square lattice of the control and an additional spatial variation of the vortex beam allows the emergence of higher diffraction orders and variable gain due to double transparency windows in this complex optical system. We believe that our proposed scheme might be useful in optical memory devices via the storage of information to diffraction orders of the atomic grating. [ABSTRACT FROM AUTHOR]

We propose a scheme to study the electromagnetically induced grating (EIG) of surface polaritons (SPs) in a negative index metamaterial/rare-earth-ion-doped crystal interface waveguide system, based on coherent population oscillation (CPO) modulating by a standing wave control field. Absorption grating can be formed via the large absorption modulation induced by the linear susceptibility of the system; the diffraction of SPs can be realized but with a very small first-order diffraction efficiency and the phase modulation in this case, is negligible. However, when the giant Kerr nonlinearity is taken into account, the phase modulation can be significantly enhanced and accompanied by high transmission at the same time, thus, a phase grating, which effectively diffracts SPs into a high-order direction, can be induced. For both the absorption and phase grating, the dependencies of the first-order diffraction efficiency on the Rabi frequency of the standing wave control field, optical detuning, and interaction length are discussed. The results obtained here have certain theoretical significance for spectral enhancements and precision measurements at the micro–nanoscales. [ABSTRACT FROM AUTHOR]

We investigate the realization and manipulation of a two-dimension (2D), asymmetric, electromagnetically induced grating (EIG) in a sample of Rydberg atoms exhibiting the van der Waals ( v d W ) interactions. The scheme relies on the application of a strong control field and a weak probe field, with the former periodically modulated in a 2D plane and the latter incident perpendicular to the 2D plane. We find that the probe field can be diffracted into an asymmetric intensity distribution depending on the relevant modulation parameters of the control field, as well as the density and length of the atomic sample. In particular, higher-order diffraction intensities can be enhanced in different ways as the v d W interaction, modulation strength, or sample length is increased. It is also of interest that the asymmetric diffraction distribution can be shifted to different quadrants by choosing appropriate modulation phases of the control field. These results may be used to develop new photonic devices with asymmetric diffraction properties required in future all-optical networks. [ABSTRACT FROM AUTHOR]

We propose an atomic grating based on an electromagnetically induced transparency phenomenon that switches between zeroth-order diffraction to a distinct higher-order diffraction pattern by driving a planar gaseous medium of a four-level tripod ( $\pitchfork$ ) atoms with three laser beams: modulation of standing wave control beam propagating nearly perpendicular to the planar medium, while vortex and weak plane probe beams directed perpendicular to the medium. We numerically investigate the behavior of the amplitude, phase modulations, and probe field diffraction intensities of different orders by the variation of the field detunings and orbital angular momentum number of the composite vortex light beam. Specifically, in the off-resonant case, the interplay between a square lattice of the control and an additional spatial variation of the vortex beam allows the emergence of higher diffraction orders and variable gain due to double transparency windows in this complex optical system. We believe that our proposed scheme might be useful in optical memory devices via the storage of information to diffraction orders of the atomic grating.

In this paper, we investigated the electromagnetically induced phase grating in a four-level quantum system with closed loop configuration via relative phase between applied fields. We found that the diffraction intensity can be adjusted via intensities and relative phase of applied lights. We also studied separately the diffraction patterns of amplitude and phase modulations of the probe light by controlling the intensity of cycling field. We found that the probe energy can transfer from zero order to high orders of diffraction when the phase modulation of the probe light becomes important. This study may be used for application in novel photonic devices in future quantum information processing. [ABSTRACT FROM AUTHOR]

We investigate the realization and manipulation of a two-dimension (2D), asymmetric, electromagnetically induced grating (EIG) in a sample of Rydberg atoms exhibiting the van der Waals (vdW) interactions. The scheme relies on the application of a strong control field and a weak probe field, with the former periodically modulated in a 2D plane and the latter incident perpendicular to the 2D plane. We find that the probe field can be diffracted into an asymmetric intensity distribution depending on the relevant modulation parameters of the control field, as well as the density and length of the atomic sample. In particular, higher-order diffraction intensities can be enhanced in different ways as the vdW interaction, modulation strength, or sample length is increased. It is also of interest that the asymmetric diffraction distribution can be shifted to different quadrants by choosing appropriate modulation phases of the control field. These results may be used to develop new photonic devices with asymmetric diffraction properties required in future all-optical networks.

We propose a scheme to study the electromagnetically induced grating (EIG) of surface polaritons (SPs) in a negative index metamaterial/rare-earth-ion-doped crystal interface waveguide system, based on coherent population oscillation (CPO) modulating by a standing wave control field. Absorption grating can be formed via the large absorption modulation induced by the linear susceptibility of the system; the diffraction of SPs can be realized but with a very small first-order diffraction efficiency and the phase modulation in this case, is negligible. However, when the giant Kerr nonlinearity is taken into account, the phase modulation can be significantly enhanced and accompanied by high transmission at the same time, thus, a phase grating, which effectively diffracts SPs into a high-order direction, can be induced. For both the absorption and phase grating, the dependencies of the first-order diffraction efficiency on the Rabi frequency of the standing wave control field, optical detuning, and interaction length are discussed. The results obtained here have certain theoretical significance for spectral enhancements and precision measurements at the micro–nanoscales.

Electromagnetically induced grating (EIG) is extensively investigated as an artificial periodic structure in recent years owed to its simple reconfiguration and flexible adjustability. We report the experimental observation of EIG in cold rubidium atoms. The coupling and probe lasers are corresponding to the 5 S 1 / 2 − 5 P 1 / 2 and 5 S 1 / 2 − 5 P 3 / 2 transitions of a V-type electromagnetically induced transparency (EIT) configuration, respectively. A clear spatial intensity distribution of the probe laser with distinguished third-order diffraction pattern is recorded to character the EIG. The influence of the pertinent experimental parameters, such as coupling laser intensity and two-photon detuning on the diffraction pattern is investigated in detail. This is the first observation in visual form of the EIG in cold rubidium atoms. These results may potentially provide a nondestructive method to image cold atoms and pave the way for investigating non-Hermitian physics and the control of light dynamics. [ABSTRACT FROM AUTHOR]

Electromagnetically induced grating (EIG) in the ladder-plus-Y double quantum dot system is modeled and the diffraction grating properties are explored in this structure. A high transmission function is obtained under the high pump field. This function is reduced under increasing the probe field due to the Kerr effect. The phase of this function depends on pumping. It is shown that the application of another two fields from the wetting layer (WL)-quantum dot (QD) type is more efficient in obtaining very high diffraction intensity. So, EIG with high diffraction intensity is obtained under a four-field application. Note that, WL-QD field effect is not studied earlier. Neglecting the WL effect reduces the transmission by five times. The diffraction intensity of this system is six times higher than that obtained from a single QD structure. [ABSTRACT FROM AUTHOR]

The radiation intensity redistribution of the probe field upon its scattering by spatially periodic atomic population gratings in a medium with a four-level tripod configuration of atomic states is investigated theoretically. Conditions are found under which a significant redistribution of the probe-wave field intensity occurs, and a "diffraction" pattern is formed with an efficient probe-field intensity transfer to the first-order maxima. [ABSTRACT FROM AUTHOR]

Electromagnetically induced grating (EIG) is extensively investigated as an artificial periodic structure in recent years owed to its simple reconfiguration and flexible adjustability. We report the experimental observation of EIG in cold rubidium atoms. The coupling and probe lasers are corresponding to the 5S1/2−5P1/2 and 5S1/2−5P3/2 transitions of a V-type electromagnetically induced transparency (EIT) configuration, respectively. A clear spatial intensity distribution of the probe laser with distinguished third-order diffraction pattern is recorded to character the EIG. The influence of the pertinent experimental parameters, such as coupling laser intensity and two-photon detuning on the diffraction pattern is investigated in detail. This is the first observation in visual form of the EIG in cold rubidium atoms. These results may potentially provide a nondestructive method to image cold atoms and pave the way for investigating non-Hermitian physics and the control of light dynamics.

We propose a scheme for generating an electromagnetically induced grating in a three-level -type atomic system via multicolor coherence. Using the multicolour coupling field, the diffraction intensity of grating, especially the first-order diffraction can be significantly enhanced. The diffraction efficiency of grating can be controlled by changing the sum of the phases and the intensity of sidebands in the trichromatic driving field, and detuning the probe field frequency. This work may be useful for designing novel photonic devices for quantum information processing, quantum networking and optical imaging. [ABSTRACT FROM AUTHOR]

We propose a scheme for creating electromagnetically induced grating in a four-level double- Λ atomic system driven by a coupling field and an incoherent pump field. Owing to the incoherent pumping process, large refractivity accompanied with vanishing absorption or even gain across the probe field can be built up in the atoms, thus phase grating or gain-phase grating, which diffracts a probe light into different directions, can be formed with the help of a standing-wave coupling field. The diffraction efficiency of the gratings can be tuned by the coupling field intensity and the incoherent pump rate, hence the proposed gratings should be suitable for beam splitter and optical switching in optical communication and networking. [ABSTRACT FROM AUTHOR]

We propose a scheme for realizing electromagnetically induced two-dimensional grating in a double-Λ system driven simultaneously by a coherent field and an incoherent pump field. In such an atomic configuration, the absorption is suppressed owing to the incoherent pumping process and the probe can be even amplified, while the refractivity is mainly attributed to the dynamically induced coherence. With the help of a standing-wave pattern coherent field, we obtain periodically modulated refractive index without or with gain, and therefore phase grating or gain-phase grating which diffracts a probe light into high-order direction efficiently can be formed in the medium via appropriate manipulation of the system parameters. The diffraction efficiency attainable by the present gratings can be controlled by tuning the coherent field intensity or the interaction length. Hence, the two-dimensional grating can be utilized as all-optical splitter or router in optical networking and communication. [ABSTRACT FROM AUTHOR]

We investigate the response of the molecular system to the magnetic field modulation. Molecular magnets are subjected to a strong standing ac magnetic field and a weak probe magnetic field. The transmission and absorption of the weak probe magnetic field can be changed due to quantum coherence and the spatially modulating of the standing field. And a electromagnetically induced grating is formed in the crystal of molecular magnets via electromagnetically induced transparency (EIT). The diffraction efficiency of the grating can be adjusted efficiently by tuning the intensity of the standing wave field and the single photon detuning. [ABSTRACT FROM AUTHOR]

We present two schemes of Lau effect for an object, an electromagnetically induced grating generated based on the electromagnetically induced effect. The Lau interference pattern is detected either directly in the way of the traditional Lau effect measurement with a classical thermal light being the imaging light, or indirectly and nonlocally in the way of two-photon coincidence measurement with a pair of entangled photons being the imaging light. [ABSTRACT FROM AUTHOR]

We study the quantum holographic imaging of one-dimensional electromagnetically induced grating created by a strong standing wave in an atomic medium. Entangled photon pairs, generated in a spontaneous parametric down-conversion process, are employed as the imaging light to realize coincidence recording. By theoretical analysis and numerical simulation, we find that both the amplitude and phase information of the object can be imaged with the characteristic of imaging nonlocally and of arbitrarily controllable image variation in size. [ABSTRACT FROM AUTHOR]

The electromagnetically induced Talbot effect offers a nondestructive and lensless way to image ultracold atoms or molecules (Wen et al., 2011 [12] ). In this paper, we propose another atomic imaging scheme based on the holographic imaging principle, in which three types of light source are employed as the imaging light to perform spatial interference. Compared to the previous self-imaging scheme, in the present one both the amplitude and phase information of the object can be imaged with the characteristic of arbitrarily controllable image variation in size, and the object to be imaged is no longer subject to the periodic structure. [ABSTRACT FROM AUTHOR]

We theoretically investigate the phenomena of electromagnetically induced grating in a doppler-broadened Λ-type three-level atomic system with the spontaneously generated coherence (SGC) effect enhanced by an incoherence pump. It is found that the model can effectively diffract a weak probe field into high-order direction. We attribute the enhancement of diffraction mainly to the quantum interference resulting from the cross coupling between the two decay pathways. The diffraction efficiency behaves phase and doppler broadening-dependent phenomena, and can be greatly modulated by the SGC effect. Compared to the counter-propagating case, the co-propagating setting is more suitable for the purpose considered in this paper due to the effectiveness of Doppler-free. [ABSTRACT FROM AUTHOR]

For the first time, we investigate the photonic band gap (PBG) structure in the static and moving electromagnetically induced grating (EIG) through scanning the frequency detunings of the probe field, dressing field and coupling field. Especially, the suppression and enhancement of the four wave mixing band gap signal (FWM BGS) and the probe transmission signal (PTS) can be observed when we scan the dressing field frequency detuning in the FWM BGS system. It is worth noting that the PBG structure and FWM BGS appear at the right of the electromagnetically induced transparency (EIT) position in the case of scanning the frequency detuning of the coupling field in the FWM BGS system, while the PBG structure and FWM BGS appears at the left of the EIT position on the condition of scanning the probe field frequency detuning. Moreover, in the moving PBG structure, we can obtain the nonreciprocity of FWM BGS. Furthermore, we can modulate the intensity, width, location of the FWM BGS and PTS through changing the frequency detunings and intensities of the probe field, dressing field and coupling field, sample length and the frequency difference of coupling fields in EIG. Such scheme could have potential applications in optical diodes, amplifiers and quantum information processing. [ABSTRACT FROM AUTHOR]

We propose a scheme to generate an electromagnetically induced grating via coherently driven four-level atoms in a N-type configuration in the presence of a standing signal field, a coupling field and a probe field. We show that a nearly ideal phase grating can be realized by adjusting the frequency detuning of signal field, the interaction length of atomic medium, and the ratio of the intensity between the signal field and the coupling field. The first-order diffraction efficiency of the grating is about 29.9 %, which is close to that of an ideal sinusoidal phase grating. [ABSTRACT FROM AUTHOR]

A new scheme for two-dimensional (2D) electromagnetically induced grating is proposed based on spontaneously generated coherence in a Λ -type atomic system, in which the atom interacts with two orthogonal standing-wave fields and an incoherent pumping field. Due to spatial periodical modulation, the zero absorption or even gain accompanied with large dispersion is obtained in atomic medium, and electromagnetically induced grating is formed. Thus the weak probe field could be diffracted into first-order or high-order directions with high efficiency. The diffraction feature and efficiency of the gratings could be adjusted by the probe field detuning, the interaction length, the incoherent pumping field intensity, and the relative phase as well. The scheme of 2D grating we presented may have some potential application in beam splitting and all-optical switching. • A scheme for 2D EIG based on SGC effect is proposed. • High efficiency EIG can be realized in a weak incoherent pumping field. • The relative phase can be used to modulate EIG effectively. • Our results may have potential application in beam splitting and all-optical switching. [ABSTRACT FROM AUTHOR]

Abstract: We study the electromagnetically induced grating in an transition interacting with a weak probe, a strong standing-wave coupling field and a static magnetic field. With a standing-wave coupling field, the phase modulation effectively diffracts a weak probe light into the first-order direction by applying a static magnetic field. Moreover, the diffraction pattern of probe beam could be dynamically tuned by manipulating the magnetic field, and the high efficiency of phase grating can be obtained by choosing the proper parameters. [Copyright &y& Elsevier]