Absorption Of Probe Field Research Articles

Topologically protected optomechanically induced transparency in a one-dimensional optomechanical array

We investigate the optomechanically induced transparency (OMIT) in an optomechanical lattice. By controlling the frequency of the external drivings in a periodic manner, the optomechanical lattice can be regarded as a Su-Schrieffer-Heeger model. By calculating the local photon density of states for the system, we investigate the response of the system to a weak probe field. In the nondeep topological nontrivial phase, we find that the system has two nondegenerate edge modes due to the finite size of the system. In this regime, a narrow transparency window of the probe field, which is much narrower than the scale set by photon decay, can be observed due to the destructive interference of the probe field absorption paths induced by the two nondegenerate edge modes. In the deep topological nontrivial phase, the two edge modes become degenerate and the narrow transparency window changes into a wide absorption window. The OMIT of the optomechanical array can also be observed in the presence of large disorders of the many-photon optomechanical couplings. Our work generalizes the OMIT of a single optomechanical cavity to a topological optomechanical system and might have potential applications in quantum information processing and quantum optical devices.

Спектры поглощения пробного сигнала и резонансной флуоресценции для излучателей при их взаимодействии с локальным окружением в прозрачных средах

The current paper demonstrates theoretical analysis of two types of spectral curves for several configurations of system of two-level light emitters, considering the influence of local field and close environment inside a transparent medium. Probe field absorption spectra and resonant fluorescence spectra are calculated under excitation of a strong monochromatic cw laser. The sensitivity of absorption and emission optical spectroscopy method is compared for revealing the effects of the medium on individual emitters and their ensembles. Spectral curves were calculated for model emitters considering local field influence of a transparent dielectric medium and local electron-phonon interactions, which determined the response of the emitters to an external laser field and effective relaxation mechanisms. The calculation formalism is based on a semiclassical approach, while the relaxation processes associated with the phonon contribution are introduced phenomenologically with references to other studies.

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The current paper demonstrates theoretical analysis of two types of spectral curves for several configurations of system of two-level light emitters, considering the influence of local field and close environment inside a transparent medium. Probe field absorption spectra and resonant fluorescence spectra are calculated under excitation of a strong monochromatic cw laser. The sensitivity of absorption and emission optical spectroscopy method is compared for revealing the effects of the medium on individual emitters and their ensembles. Spectral curves were calculated for model emitters considering local field influence of a transparent dielectric medium and local electron-phonon interactions, which determined the response of the emitters to an external laser field and effective relaxation mechanisms. The calculation formalism is based on a semiclassical approach, while the relaxation processes associated with the phonon contribution are introduced phenomenologically with references to other studies.

Lateral and rotary light-drag enhancement in a vee+ladder configuration comprising a Rydberg state

The lateral and rotary light-drag effects in a four-level vee+ladder configuration comprising a Rydberg state as the topmost level is theoretically investigated. We found that it is difficult to obtain enhanced lateral and rotary light drags accompanied by suppressed absorption in the three-level vee and ladder configurations. However, in the proposed four-level vee+ladder configuration both lateral and rotary light drags are significantly enhanced as well as suppressing the absorption of the weak probe field via electromagnetically induced transparency (EIT). The profound impacts of the intensity of the controlling fields on both the lateral and rotary light drags are discussed. It is demonstrated that intensifying the controlling fields leads to enhancing the lateral and rotary light-drag effects accompanied by negligible probe field absorption. Furthermore, it is shown that light is dragged opposite of the direction of the host medium motion while the superluminal light propagation dominates. Nevertheless, the light is dragged along the same direction of the host medium motion in the subluminal propagation condition. In addition, we present the real quantities of all the parameters used in this study for future empirical investigations.

Controllable two- and three-dimensional atom localization via spontaneously generated coherence

A scheme for two-dimensional (2D) and three-dimensional (3D) atom localization in a four-level N-type atomic system is proposed. The scheme is based on the probe absorption measurement when the atom passes through the orthogonal standing-wave fields. Using the electromagnetically induced transparency, we prove that the probe field absorption is spatially localized in sub-wavelength domain. We also show that the spatial resolution of 2D and 3D atom localization strongly depends on the probe field detuning, the quantum interference parameters induced by spontaneous emission, and the relative phase between the driving fields.

Tunable multiwindow magnomechanically induced transparency, Fano resonances, and slow-to-fast light conversion

We investigate the absorption and transmission properties of a weak probe field under the influence of a strong control field in a cavity magnomechanical system. The system consists of two ferromagnetic-material yttrium iron garnet (YIG) spheres coupled to a single cavity mode. In addition to two magnon-induced transparencies (MITs) that arise due to magnon-photon interactions, we observe a magnomechanically induced transparency (MMIT) due to the presence of nonlinear magnon-phonon interaction. We discuss the emergence of Fano resonances and explain the splitting of a single Fano profile to double and triple Fano profiles due to additional couplings in the proposed system. Moreover, by considering a two-YIG system, the group delay of the probe field can be enhanced by one order of magnitude as compared with a single-YIG magnomechanical system. Furthermore, we show that the group delay depends on the tunability of the coupling strength of the first YIG with respect to the coupling frequency of of the second YIG, and vice versa. This helps to achieve larger group delays for weak magnon-photon coupling strengths.

Azimuthal modulation of probe absorption and transfer of optical vortices

We analyze azimuthal modulation of probe field absorption profile in a closed four-level inverted Y-type atomic system. We employ a Laguerre–Gaussian beam and a microwave field to realize spatially varying atomic susceptibility, which is responsible for the generation of structured light. An extra nonvortex control beam is used to ensure electromagnetically induced transparency at the core of Laguerre–Gaussian beam. Our proposed model exhibits both absorption and gain at different azimuthal angles, and orbital angular momentum of light can be identified via absorption profile of the probe field. We further discuss the transfer of optical vortices from Laguerre–Gaussian beam to the transmitted probe field.

Innovative fiber Bragg grating filter based on a graphene photonic crystal microcavity.

We propose a new model for a fiber Bragg grating (FBG) filter based on one-dimensional defective photonic bandgap structures, which operates within telecom windows. The device is realized in an asymmetric $ {{\rm SiO}_2}/{{\rm TiO}_2} $SiO2/TiO2 photonic crystal (PC) microcavity with the defect layer of the graphene disk placed in the center of the structure. The theoretical analysis of the optical properties of the narrowband FBG filter is given based on the combination of the density matrix approach with the transfer matrix method. The effect of the incident angle and the polarization of the probe field on the transmittance spectra is calculated. Also, tuning the filtering wavelength and the number of guided modes is performed by changing the properties of PC's defect layer. It is shown that depending on the ratio of the coupling fields' intensity, the probe field absorption can be minimized and even be amplified in $ {\lambda _0} = 1550\;{\rm nm} $λ0=1550nm. The results show very promising potential for fabrication of FBG filters operating in the near-infrared regime for light wave communications.

Dynamical and steady-state properties of absorption-dispersion curves in a monolayer graphene system

In this article, we discuss the dynamic and steady-state features of the absorption-dispersion of a graphene monolayer system, interacting with an elliptically polarized control and coherent pumping fields. We find that, under a proper condition of parameters selection, the absorption, dispersion and group index of the weakly probe field in a monolayer graphene system can be adjusted. We show that, under optimal conditions, the controlling of the group velocity can be possible to achieve the subluminal and superluminal light propagation. Moreover, we realize that the amplification of the probe light due to the presence and absence of population inversion can be obtained by the proper choice of controllable parameters. Our findings may be useful for high-speed optical communications based on a graphene monolayer system.

Light amplification without population inversion in one-dimensional photonic crystal doped by rare-earth ions

Abstract Probe field amplification without population inversion in a one-dimensional photonic crystal (1DPC) doped by four-level rare-earth ions is proposed. By controlling the intensity of the coupling field, probe field absorption with population inversion converts to probe field amplification without population inversion. It is found that the amount of probe field amplification through the photonic crystal doped by rare-earth ions is larger than the probe field amplification for the same ions in free space. For a particular coupling field intensity, i.e. Ω c = 5.1 Γ , the probe field absorption converts to probe field amplification just by manipulating the probe field detuning.

Efficient two-dimensional sub-wavelength atom localisation via probe absorption in a four-level Λ-shaped atomic system

Two-dimensional (2D) atom localisation of a four-level Λ-shaped atomic system with a nearly hyper-fine doublet interacting with two orthogonal standing-wave fields is investigated. The spatial information of a moving atom in xy plane is obtained by measuring the probe field absorption. The effect of quantum interference on two-dimensional atom localisation is described. The intensity of standing-waves and the detuning of the probe and standing-wave fields are found to strongly affect the two-dimensional atom localisation that lead to different spatial distribution patterns.

Azimuthal modulation of electromagnetically induced transparency using structured light.

Recently a scheme has been proposed for detection of the structured light by measuring the transmission of a vortex beam through a cloud of cold rubidium atoms with energy levels of the Λ-type configuration [N. Radwell et al., Phys. Rev. Lett.114, 123603 (2015) ]. This enables observation of regions of spatially dependent electromagnetically induced transparency (EIT). Here we suggest another scenario for detection of the structured light by measuring the absorption profile of a weak nonvortex probe beam in a highly resonant five-level combined tripod and Λ (CTL) atom-light coupling setup. We demonstrate that due to the closed-loop structure of CTL scheme, the absorption of the probe beam depends on the azimuthal angle and orbital angular momentum (OAM) of the control vortex beams. This feature is missing in simple Λ or tripod schemes, as there is no loop in such atom-light couplings. One can identify different regions of spatially structured transparency through measuring the absorption of probe field under different configurations of structured control light.

Phase Control of Transient Optical Properties of Double Coupled Quantum-Dot Nanostructure via Gaussian Laser Beams

We theoretically analyze the transient properties of a probe field absorption and dispersion in a coupled semiconductor double-quantum-dot nanostructure. We show that in the presence of the Gaussian laser beams, absorption and dispersion of the probe field can be dramatically influenced by the relative phase between applied fields and intensity of the Gaussian laser beams. Transient and steady-state behaviors of the probe field absorption and dispersion are discussed to estimate the required switching time. The estimated range is between 5–8 ps for subluminal to superluminal light propagation.

Phase control of transmission in one-dimensional photonic crystal with defect layer doped by quantum dots

We discuss the propagation of an electromagnetic field through one-dimensional photonic crystal doped by quantum-dot molecules in defect layer. It is shown that in the presence of inter-dot tunneling, the transmitted and the reflected light pulse completely become phase dependent. By proper choice of the phase deference between applied fields probe field amplification through one-dimensional photonic crystal has been obtained. In this way, simultaneous subluminal transmission and reflection are achieved. The transient behavior of probe field absorption and the slope of dispersion are also presented.

Photon drag enhancement by a slow-light moving medium via electromagnetically-induced transparency amplification

Recently, a considerable enhancement has been observed in the celebrated Fresnel–Fizeau light drag by innovative experimental and theoretical approaches because of its fundamental and practical interest in the emerging technology of quantum optics and photonics. We present a semiclassical density matrix approach on the demonstration of light drag in a slow-light moving medium comprising five-level single tripod atomic configuration. To accomplish this, we introduce Kerr-type nonlinearity that leads to electromagnetically-induced transparency amplification under resonance conditions. By switching ON Kerr-type nonlinearity effect, we observe a prominent transparency window in probe field's absorption spectrum whose width and amplitude can be controlled further by the intensity of Kerr field and control field. The incorporation of Kerr field also switches light propagation from superluminal to subluminal domain. We predict a significant enhancement both in the lateral and the rotary photon drag owing to drag of light linear polarization state subjected to translation and rotation of the host medium, respectively. Consistent with earlier results, light drag considerably depends on both transverse and angular velocity of the host medium. In regime of subluminal propagation, light polarization state drags along the medium motion while in the superluminal propagation region it drags opposite to the medium motion.

Effects of electric field and structure on the electromagnetically induced transparency in double quantum dot

We theoretically investigated the effects of electric field and structural parameters of the confining potential on the optical properties of a GaAs/AlGaAs double quantum dot related to the occurrence of the electromagnetically induced transparency phenomenon, using the compact density-matrix formalism and the effective mass approximation. The dependences of the absorption coefficient, refraction index and light group velocity on the Rabi frequency of the control field, intensity of the static electric field, asymmetry parameter of the potential and dot dimension are discussed in detail. It is found that electromagnetically induced transparency occurs in the system for intermediate field values and its transparency window for probe field absorption and sub- and super-luminal frequency interval of the probe field are blueshifted by the increment of the electric field strength and dot dimension but are redshifted by the augment of the asymmetry parameter of the potential.

Plasmonic Control of Refractive Index Without Absorption in Metallic Photonic Crystals Doped with Quantum Dots

We investigate the refractive index without absorption in metallic photonic crystals doped with quantum dots. It is found that the absorption and dispersion of probe field can be easily controlled via adjusting properly the corresponding parameters of the system. The effect of the dipole-dipole interaction has also been included in the formulation, which leads to interesting phenomena. Our scheme opens the possibility to control the refractive index without absorption in polaritonic materials doped with nanoparticles.

Mixture of Electromagnetically Induced Transparency and Autler–Townes Splitting in a Five-Level Atomic System**Supported by the National Natural Science Foundation of China under Grant Nos. 11274132, 11547208, and the Science Foundation of China Three Gorges University

Discerning electromagnetically induced transparency (EIT) from Autler–Townes splitting (ATS) is a significant issue in quantum optics and has attracted wide attention in various three-level configurations. Here we present a detailed study of EIT and ATS in a five-level atomic system considered to be composed of a four-level Y-type subsystem and a three-level Λ-type subsystem. In our theoretical calculations with standard density matrix formalism and steady-state approximation, we obtain the general analytical expression of the first-order matrix element responsible for the probe-field absorption. In light of the well-known three-level EIT and ATS criteria, we numerically show an intersection of EIT with ATS for the Y-type subsystem. Furthermore, we show that an EIT dip is sandwiched between two ATS dips (i.e., multi-dip mixture of EIT and ATS) in the absorption line for the five-level system, which can be explained by the dressed-state theory and Fano interference.

Two-dimensional Sub-wavelength Atom Localization of a Four-Level $$\varLambda$$ Λ -type Atomic System with two Adjacent Lower Levels Via Probe Absorption

Two-dimensional atom localization of a four-level \(\varLambda\)-shaped atom with two adjacent lower levels interacting with two orthogonal standing wave fields is considered. By measuring the probe field absorption, spatial information of position of a moving atom is obtained in \(x - y\) plane. The position of atom through two-dimensional standing wave field strongly depends on the intensity of standing waves, detuning of the probe and standing wave fields. Choosing the appropriate controlling parameters, the two-dimensional atom localization through the standing wave fields in a sub-wavelength domain will be achieved.

Propagation of a laser pulse and electro-optic switch in a GaAs/AlGaAs quadruple-coupled quantum dot molecule nanostructure

Based on a GaAs/AlGaAs quadruple-coupled quantum dot heterostructure, an optical switch for controlling superluminal and subluminal light propagation is suggested. The transient and steady state behaviour of the absorption and dispersion of a probe pulse laser field through a quadruple quantum dot molecule are studied. We show that the group velocity of a light pulse can be controlled from superluminal to subluminal, or vice versa, by controlling the tunnelling rates between the quantum dots. The required switching time is calculated and we find it to be about 8 ps. We also investigated a method for the all-optical switching of probe field absorption from a large amount to nearly zero just by applying an incoherent pumping field. We estimated the required switching time for this case to be between 3 and 14 ps.