Three-level Atomic Medium Research Articles

Electromagnetically induced grating via amplitude and phase modulations in a three-level V-type atomic medium

Abstract A probe laser beam can be completely absorbed in an atomic resonance frequency region, however, if a coupling laser beam is further applied to the atom, the atomic medium can exhibit electromagnetically induced transparency (EIT), i.e, the probe beam can be completely transmitted through the atomic medium. Thus, if the coupling beam is a standing wave field with nodes and antinodes, it will cause in space a periodic modulation of the transmitted spectrum of the probe field. This means that the probe field propagates through the atomic medium just as it passes through a diffraction grating which is called electromagnetically induced grating (EIG). Based on amplitude or phase modulation of transmission function, the absorption grating or the phase grating can be formed, respectively. In this work, based on controllable absorption and dispersion properties of a three-level V-type atomic system, we study the control of the absorption grating and the phase grating with respect to the intensity and the frequency of the laser fields. The absorption diffraction pattern at the two-photon resonance is obtained, while the phase diffraction pattern appears when there is a frequency shift of either the coupling frequency or the probe frequency compared to the corresponding atomic resonance frequency. By adjusting the coupling or/and probe laser frequency, the absorption grating can be converted into the phase grating and the high-order diffraction efficiency can also be improved.

Generation and control of population difference gratings in a three-level hydrogen atomic medium using half-cycle attosecond pulses nonoverlapping in the medium

Generation and control of population difference gratings in a three-level hydrogen atomic medium using half-cycle attosecond pulses nonoverlapping in the medium

All optical switching in a three-level V-type atomic medium based on electromagnetically induced transparency

All optical switching in a three-level V-type atomic medium based on electromagnetically induced transparency

Dynamical propagation and all-optical switching in a ladder-type three-level system under the influence of spontaneously generated coherence

We investigate the dynamical of pulse propagation and all-optical switching via a spontaneously generated coherence (SGC) in a three-level ladder-type atomic medium driven by a coupling field under the presence of incoherent pumping. Results show that the SGC causes modulations at the leading edge of the pulse envelope shape. These modulations increase with the together growth of SGC and distance. Furthermore, it is shown that the continuous-wave input probe field is switched ON or OFF by periodically modulating the coupling field. The spontaneously generated coherence has a strong effect on switching efficiency and switching pulse shape. The proposed scheme may have applications in the design of optical switching and optical gain devices in optical telecommunications.

Negative refractive index in a Doppler broadened three-level Λ-type atomic medium

We have achieved a negative refractive index with significantly reduced absorption in a three-level Λ-type atomic gas medium under Doppler broadening. It shows that the conditions for obtaining negative refractive index in the presence of Doppler broadening are very different from those of Doppler broadening absent. In particular, in order to obtain negative refractive index in the case of Doppler broadening the coupling laser intensity must be approximately ten times greater than that when the Doppler broadening is ignored. Meanwhile, the frequency band of negative refractive index with Doppler broadening is significantly expanded (about a hundred times) compared to that without Doppler broadening, however, the amplitude of negative refractive index decreases with increasing temperature (or Doppler width). Even in some cases as temperature (Doppler width) increases, the left-handedness of the material can disappear. In addition, we also show that the amplitude and the frequency band of negative refractive index can be changed by adjusting the intensity and the frequency of coupling laser. Our theoretical investigation can be useful for selection of laser parameters under different temperature conditions to achieve negative refractive index in experimental implementation.

All-optical switching via spontaneously generated coherence, relative phase and incoherent pumping in a V-type three-level system

All-optical switching in a V-type three-level atomic medium is studied and controlled by spontaneously generated coherence (SGC), relative phase of applied fields and incoherent pumping rate. By simultaneously numerical solving the coupled Maxwell–Bloch equations for atom and field on a spatio-temporal grid, we have observed a continuous-wave probe field is switched ON or OFF by periodically modulating the coupling field intensity or the relative phase of applied fields. It also is shows that although the SGC can distort the switching probe pulse, however, under the SGC the response of the medium depends sensitively on the relative phase, and the probe field can be switched synchronous or anti-synchronous with the relative phase. On the other hand, in order to overcome the switching pulse distortion caused by SGC, we have included an incoherent pumping field. By choosing the appropriate phase and pumping rate, the fluctuations of switching probe pulse can be easily overcome. The proposed model can be useful for the design of optical switches and optical storage devices as well as possible experimental implementations.

Subluminal and superluminal light pulse propagation under external magnetic field in a vee-type three-level atomic medium

In this work, we investigate subluminal and superluminal light propagation in a vee-type three-level atomic medium under an external magnetic field. The dispersion and absorption behaviors are studied for the cases of absence and presence of a magnetic field. It is found that under an electromagnetically induced transparency condition, the light pulse can be switched between subluminal and superluminal propagation by ON-OFF switching of the magnetic field. Finally, the transient response of the medium is discussed, which shows that the considered scheme has potential applications in magneto-optic switching devices. Full Text: PDF ReferencesBoller K J, Imamoglu A, Harris S E, "Observation of electromagnetically induced transparency", Phys. Rev. Lett. 66 (1991) 2593. CrossRef Fleischhauer M, Imamoglu A, Marangos J P, "Electromagnetically induced transparency: Optics in coherent media", Rev. Mod. Phys. 77 (2005) 633. CrossRef L.V. Hau, S. E. Harris, Z. Dutton, C.H. Bejroozi, "Light speed reduction to 17 metres per second in an ultracold atomic gas", Nature, 397 (1999) 594. CrossRef Z. Dutton, N.G.C. Slowe, L.V. Hau, "The art of taming light: ultra-slow and stopped light", Europhysics News, 35 (2004) 33. CrossRef V. Bharti, V. Natarajan, "Sub- and super-luminal light propagation using a Rydberg state", Opt. Commun. 392 (2017) 180-184. CrossRef Khoa D X, Doai L V, Son D H and Bang N H, "Enhancement of self-Kerr nonlinearity via electromagnetically induced transparency in a five-level cascade system: an analytical approach", J. Opt. Soc. Am. B. 31 (2014) 1330. CrossRef Hamedi H R, Gharamaleki A H, and Sahrai M, "Colossal Kerr nonlinearity based on electromagnetically induced transparency in a five-level double-ladder atomic system", Appl. Opt 22 (2016) 5892. CrossRef A. Fountoulakis, A.F. Terzis, E. Paspalakis, "All-optical modulation based on electromagnetically induced transparency", Phys. Lett. A 374, (2010) 3354. CrossRef Khoa D X, Doai L V, Mai Anh L. N, Trung L. C, Thuan P. V, Dung N. T, and Bang N. H, J. "Optical bistability in a five-level cascade EIT medium: an analytical approach", Opt. Soc. Am. B, 33 (2016) 735. CrossRef Hoang Minh Dong, and Nguyen Huy Bang, "Controllable optical switching in a closed-loop three-level lambda system", Phy. Scr. 94, (2019) 115510. CrossRef Dong H M, Doai L V, Sau V N, Khoa D X and Bang N H, "Propagation of a laser pulse in a three-level cascade atomic medium under conditions of electromagnetically induced transparency", Photonics Letter of Poland, 3 (2016) 73. CrossRef Khoa D X, Dong H M, Doai L V and Bang N H, "Propagation of laser pulse in a three-level cascade inhomogeneously broadened medium under electromagnetically induced transparency conditions", Optik 131 (2017) 497. CrossRef H. M. Dong, L.V. Doai, and N.H. Bang, "Pulse propagation in an atomic medium under spontaneously generated coherence, incoherent pumping, and relative laser phase", Opt. Commun. 426 (2018) 553-557. CrossRef Jiahua Li, Rong Yu, Liugang Si, and Xiaoxue Yang, "Propagation of twin light pulses under magneto-optical switching operations in a four-level inverted-Y atomic medium", J. Phys. B: At. Mol. Opt. Phys. 43 (2010) 065502. CrossRef S. H. Asadpour, H. R. Soleimani, "Polarization dependence of optical bistability in the presence of external magnetic field", Opt. Commun 310 (2014) 120-124. CrossRef H.M. Dong, L.T.Y. Nga, and N.H. Bang, "Optical switching and bistability in a degenerated two-level atomic medium under an external magnetic field", App. Opt. 58, (2019) 4192. CrossRef H. M. Dong, L. T. Y. Nga, D. X. Khoa, N. H. Bang, "Controllable ultraslow optical solitons in a degenerated two-level atomic medium under EIT assisted by a magnetic field", Sci. Rep. 10 (2020) 15298. CrossRef Daniel A. Steck, "Rubidium 87D Line Data," http://steck.us/alkalidata. CrossRef

Spatial-dependent probe transmission based high-precision two-dimensional atomic localization

Herein, we propose a scheme for the realization of two-dimensional atomic localization in a λ-type three-level atomic medium such that the atom interacts with the two orthogonal standing-wave fields and a probe field. Because of the spatially dependent atom-field interaction, the information about the position of the atom can be obtained by monitoring the probe transmission spectra of the weak probe field for the first time. A single and double sharp localized peaks are observed in the one-wavelength domain. We have theoretically archived high-resolution and high-precision atomic localization within a region smaller than λ/25 × λ/25. The results may have potential applications in the field of nano-lithography and advance laser cooling technology.

Manipulating the steady-state entanglement via three-level atoms in a hybrid levitated optomechanical system

We theoretically investigate the generation of steady-state entanglement in a levitated optomechanical system with a cascade three-level atomic medium and a dielectric nanosphere. There are two cavity modes, driven by two external laser beams with different frequencies, which are responsible for trapping and cooling the nanosphere. Atoms prepared in coherent superposition are injected into the cavity to manipulate the optical fields and the effective optomechanical coupling. We show that the entanglement between the nanosphere and the cavity modes can be enhanced by selecting properly the initial population of the lower atomic level. In particular, when the atoms are prepared at that level, the corresponding optomechanical entanglement increases with the increase of the atom-field coupling strength. We also investigate in detail the influence of the effective cavity field detunings, the atomic detunings, the driving power, and the nanosphere's radius and found that there exist optimal values of the effective cavity field detuning and the driving power that maximize the optomechanical entanglement. By selecting the system's parameters properly, we further demonstrate the generation of genuine tripartite entanglement between three degrees of freedom in the system. The findings here may help flexible control of the steady-state entanglement in hybrid optomechanical systems.

Population Gratings Created by a Pair of Unipolar Attosecond Pulses in a Three-Level Atomic Medium

The possibility of inducing population gratings in a three-level resonant medium using a pair of unipolar attosecond pulses that do not overlap in the medium has been studied theoretically. It has been shown that the results of the approximate solution of the Schrodinger equation agree with the results of the numerical solution of the system of equations for the density matrix of a three-level medium whose parameters are close to the parameters of atomic vapors of rubidium.

Analog multicolor optomechanically induced transparency in a distant cavity-optomechanical system assisted by a three-level atomic medium

The multiple optomechanically induced transparency (OMIT) of a compound optomechanical system is studied. The system contains two distant cavities and one of the cavity is filled with a three-level atomic medium. We focus on the number of OMIT windows, which is influenced by the coherent interactions between the system components. We find that four transparency windows can be observed from the output field at the probe frequency. When some of the internal interactions disappear, the number of transparent windows decreases. Moreover, we studied the influence of various factors on OMIT. The results show that the number and the width of the transparent windows are affected by the classical driving power, the coupling strength (between cavity field and atoms or between the two cavities), as well as the Rabi frequency. Our study provides a great flexibility for phonon storage and has potential applications in quantum information processing.

Modifying optical properties of three-level V-type atomic medium by varying external magnetic field

Optical properties including absorption, dispersion, group index, Kerr nonlinearity, and optical bistability of a three-level V-type atomic medium have modified by varying an external magnetic field. By changing the magnitude or the sign of the external magnetic field, the transparency window with normal dispersion transfers to the enhanced absorption with anomalous dispersion at the line center, and hence the light propagation switches between subluminal and superluminal modes. The magnitude and the sign of the Kerr nonlinearity are controlled with the strength and the sign of the magnetic field. As a consequence, the behaviors of optical bistability are also made to appear or disappear when switching on/off the magnetic field. Moreover, the threshold intensity and width of optical bistability are also changed by the magnetic field and the coupling field. The results can be used to control the working characteristics of applied devices and study the related effects.

Double electromagnetically induced transparency windows in the [formula omitted]-type three-level atoms-assisted optomechanical system

We investigate electromagnetically induced transparency (EIT) in an optomechanical system that consists of a Λ-type three-level atomic medium confined inside an optical cavity with an oscillating mirror in the one end. The atoms are driven by a quantized field that acts as a control field of the EIT system and the quantized cavity field is known as a probe field. It can be seen double EIT windows separated by an absorption peak at the center of the EIT window in the output probe field. We analyse in detail effect of the photon numbers of the control and probe fields, the phonon number and the frequency of the oscillating mirror on the transparency windows. The results show that the width of transparency windows increases with the increase of the photon number of the control field and the phonon number of the oscillating mirror. Also, it is shown that the full width at half maximum (FWHM) of the absorption peaks changes with changing the above-mentioned parameters.

Solitary waves propagation in three-level atomic media

In this paper analytical solutions of a non-linear differential equations describing solitary wave-pair propagation are derived as well as the existence conditions in absorbing optical dense media.

Propagation of a laser pulse under electromagnetically induced transparency conditions

We investigate the propagation dynamics of a pair of probe and coupling laser pulses in a three-level type-V atomic medium under the condition of electromagnetically induced transparency (EIT) by numerical solving the Maxwell-Bloch equations for atoms and fields. Influences of the intensity and pulse area of the coupling laser on the EIT formation of probe laser pulse are studied in a wide region from micro- to pico-second of pulse duration. It is found that a nearly solition pulse can be established at the smallest pulse area in the pico-second region and with the largest pulse area in the micro-second region. These results can be important for applications in all-optical switching, and quantum information processing and transmission.

Surface polaritonic solitons and breathers in a planar plasmonic waveguide structure via electromagnetically induced transparency

We propose a scheme for the coupler-free excitation of surface polaritonic solitons and breathers in a planar plasmonic waveguide structure comprising of a transparent layer, a metal layer and a layer of three-level lambda-type atomic medium. In the proposed system, an enhanced Kerr nonlinearity is achieved via electromagnetically induced transparency (EIT) in the bottom atomic medium, which can be controlled through proper modulation of the frequency detunings and Rabi frequencies of the driving laser fields. This nonlinearity balances the dispersion in the system, thus providing the necessary condition for the excitation of polaritonic solitons in the proposed system. As a result, the system yields laterally self-trapped bright and dark surface polaritonic solitons which are tightly guided at the interface of the metal and the EIT medium. Furthermore, we investigate the excitation of surface polaritonic Akhmediev breathers at the metal-EIT medium interface in the proposed system. A stable propagation of the surface polaritonic Akhmediev breathers is achieved with proper choice of parameters in the proposed planar plasmonic waveguide structure. This experimentally feasible scheme could be significant in the development of highly compact nano-photonic devices in the optical regime.

Influences of polarization and relative phase of laser fields on the optical properties of three-level cascade atomic medium

In this work, we study the influences of interference parameter of spontaneously emissions (generated by the polarization of light and the non-orthogonal orientation of electric dipole moments) p and relative phase of the laser fields  on the absorption and dispersion coefficients of 85Rb three-level cascade atomic medium by analytical method. The results show that the influence of parameter p leads to a narrower of the transparent window, while the absorption spectrum on both sides of the transparent window is enhanced. This increases the slope of normal dispersion curve inside the transparent spectral domain; the absorption and dispersion coefficients vary according to the phase difference with the period of 2. At  = 0 and  = 2, the absorption coefficient is largest, while at  = , the absorption coefficient is smallest. For dispersion coefficient, at  = 0,  = 2 and  = , the dispersion coefficient is vanished, while it reaches the extreme value when  = /2 and  = 3/4. Analytical results are useful for experimental observation and related applications.

Pulse propagation in an atomic medium under spontaneously generated coherence, incoherent pumping, and relative laser phase

Influences of spontaneously generated coherence (SGC) and relative phase of laser fields on a probe laser pulse propagating in a three-level cascade atomic medium under incoherent pumping and electromagnetically induced transparency (EIT) are studied theoretically. It is shown that the leading edge of the pulse oscillates during its propagation. Furthermore, the oscillating magnitude is enhanced by growing SGC, however, it can be depressed by choosing a suitable relative phase between the laser fields. Indeed, the probe pulse depends sensitively on the relative phase with a period of 2 π in which it oscillates strongest at ϕ=0, π and 2 π; whereas it is unchanged at ϕ=π∕2 and 3π/2. On the other hand, the influences of SGC and the relative phase on the pulse envelope are more effective as growing the incoherent pumping rate.

Dipolar exchange induced transparency with Rydberg atoms

A three-level atomic medium can be made transparent to a resonant probe field in the presence of a strong control field acting on an adjacent atomic transition to a long-lived state, which can be represented by a highly excited Rydberg state. The long-range interactions between the Rydberg state atoms then translate into strong, non-local, dispersive or absorptive interactions between the probe photons, which can be used to achieve deterministic quantum logic gates and single photon sources. Here we show that long-range dipole–dipole exchange interaction with one or more spins—two-level systems represented by atoms in suitable Rydberg states—can play the role of control field for the optically dense medium of atoms. This induces transparency of the medium for a number of probe photons np not exceeding the number of spins ns, while all the excess photons are resonantly absorbed upon propagation. In the most practical case of a single spin atom prepared in the Rydberg state, the medium is thus transparent only to a single input probe photon. For larger number of spins ns, all np ≤ ns photon components of the probe field would experience transparency but with an np-dependent group velocity.

Low-noise optical field phase-shifting manipulated using a coherently-prepared three-level atomic medium

We propose a multifunction phase-shifting manipulator with low noise at a single-photon level,by using a threelevel atomic scheme.This three-level system interacts with a strong pumping field and a weak probe field with a large detuning.Due to this large detuning,two lower states can be coherently prepared prior to the injection of the pump and probe fields.In our configuration,the duration of the pumping field is much longer than that of the probe field. By solving the Heisenberg-Langevin equations of our system under the steady state approximation,we calculate the linear susceptibility of the system and examine the quantum noise properties of the probe field in detail.We show that this scheme,which rests on the process of two-wave mixing with initial atomic coherence,exhibits many interesting properties that neither typical electromagnetically induced transparency (EIT) schemes nor active Raman gain (ARG) schemes possess.Although both EIT-and ARG-based schemes have been widely investigated in atomic medium,the direct generalizations of these schemes to the single/few photon limit prove to be more problematic.The low fidelity due to the significant probe-field attenuation in EIT medium and the large quantum noise due to the amplification of the probe field in an active Raman gain medium are the main obstacles that prohibit a high-fidelity,low-noise phase shifter from being realized in the single/few photon limit.Physically,this scheme can be viewed as a hybrid scheme in which two processes of different physical principles are allowed to interfere with each other to achieve many desired functionalities. For instance,it can be used as a lossless two-photon-broadband phase-shifter with suitable system parameters.It can also be used as an attenuator/amplifier and a total transparency with a zero phase shift.In particular,we show that by locking the pump field intensity and the two-photon detuning simultaneously a flat constant π-phase shift can be realized with unit probe fidelity in a broad probe field frequency range.Applying the quantum regression theorem,we calculate the noise spectrum of the outgoing probe field as a large phase shift is achieved,and show that this two-photon-insensitive π-phase shift may significantly reduce the quantum noise fluctuations associated with a Raman gain process,and have a lot of potential applications for quantum information processing and optical telecommunication.The realization of this broadband π-phase-shift with significantly reduced quantum noise fluctuations makes this scheme attractive for the realization of low-noise phase-gate/polarization-gate at single-photon level.