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Coherent control of the incident light propagation in a defect one-dimensional photonic crystal
Abstract
In this paper, we have discussed the transmission and reflection properties of the infrared laser pulse propagated through one-dimensional photonic crystal (1DPC) with single layer of graphene nanotrusses. The single layer graphene system interacts with a probe laser field and two coupling lights. We analytically solve the optical susceptibility of the single layer graphene system for adapting the dielectric function of the 1DPC. After that we discuss the transmission and reflection properties of the incident laser pulse on 1DPC by controlling the intensity for the coupling lights and relative phase between applied lights. We have also found that the absorption and population spectrums of the medium can be controlled by the relative phase between applied lights. Our results show that the gain without population inversion can be obtained for the simultaneous slow light propagation in the transmission and reflection pulses. Our results may have potential application in the future of the all-optical devices in quantum technologies.
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Coherent Ising machine (CIM) is a hardware solver that simulates the Ising model and finds optimal solutions to combinatorial optimization problems. However, for practical tasks, the computational process may be trapped in local minima, which is a key challenge for CIM. In this work, we design a CIM structure with a spiking neural network by adding dissipative pulses, which are anti-symmetrically coupled to the degenerate optical parametric oscillator pulses in CIM with a measurement feedback system. We find that the unstable oscillatory region of the spiking neural network could assist the CIM to escape from the trapped local minima. Moreover, we show that the machine has a different search mechanism than CIM, which can achieve a higher solution success probability and speed-up effect.
Whispering gallery mode (WGM) cavities formed by dielectric structures have attracted intensive interest in various fields. The high-quality factor and smaller mode volume associated with the optical modes have inspired experiments in nonlinear optics, nanophotonics, and quantum information science. Moreover, it also gives rise to optical biosensors and other significant applications. To further reduce the material loss of the resonator, optical gain materials, such as erbium and ytterbium, are doped into the dielectric structure to increase the nonlinear effect and enhance the interaction between light and matter. Here in this review, we outline the most recent advancements in gain-doped optical WGM microcavities. Moreover, we introduce the dynamics of the gain in WGM resonators, the integration of gain media into WGM microcavities with various shapes, and the fabrication and applications of the gain microcavities. Also, the applications of the gain cavity based on the whispering-gallery mode have been introduced, e.g., ultra-sensitive sensors, low-threshold lasers, and high-performance optical systems.
We discuss the electromagnetically induced grating (EIG) and electromagnetically induced phase grating (EIPG) in a four-level quantized graphene monolayer system. By using the density matrix technique and perturbation theory, we first obtain the self-Kerr nonlinear susceptibility of the graphene system; afterwards, we study the amplitude and phase modulations of the probe light. We discovered that the EIG and EIPG can be found by controlling the elliptically polarized coupling fields that interact with the monolayer graphene system. Owing to the phase modulation of the transmitted light beam, we recognized that the probe strength can also additionally switch from zeroth-order to high-order diffraction. Moreover, we found that the diffraction performance of the grating may be adjusted through tuning the polarization of the coupling light.
Based on double U-groove photonic crystal fiber (PCF), a surface plasmon resonance sensor with dual parametric detection of temperature and refractive index is proposed. The birefringence of PCF is increased by using germanium ions doped in the core and introducing U-shaped notches on both sides of the D-shaped fiber. The polished surface of the PCF is coated with gold film and PDMS as a temperature sensing channel, and the U-shaped groove is coated with gold film as a refractive index sensing channel. Through the design of the sensor, it is finally possible to achieve independent measurement of the two parameters. The sensor has a maximum wavelength sensitivity of 4715 nm/RIU in the analyte refractive index range of 1.32–1.4, and maximum wavelength sensitivity of 18 nm/°C in the ambient temperature range of ${-}{{30^\circ {\rm C} - 50^\circ{\rm C}}}$ − 30 ∘ C − 50 ∘ C . The proposed sensor has broad application prospects in scenarios such as blood analysis, DNA hybridization analysis, and microenvironmental cell interactions.
We discover that the spatially coherent radiation within a certain frequency range can be obtained without a common nonlinear optical process. Conventionally, the emission spectra were obtained by de-exciting excited centers from real excited energy levels to the ground state. Our findings are achieved by deploying a high-entropy glass system (HEGS) doped with neodymium ions. The HEGS exhibits a much broader infrared absorption than common glass systems, which can be attributed to be high-frequency optical branch phonons or allowable multi-phonon processes caused by phonon broadening in the system. A broadened phonon-assisted wideband radiation (BPAWR) is induced if the pump laser is absorbed by the system. The subsequent low-threshold self-absorption coherence modulation (SACM) can be controlled by changing excitation wavelengths, sample size, and doping concentrations. The SACM can be red-shifted through the emission of phonons of the excited species and be blue-shifted by absorbing phonons before they are de-excited. There is a time delay up to 1.66 ns between the pump pulse and the BPAWR when measured after traveling through a 35 mm long sample, which is much longer than the Raman process. The BPAWR-SACM can amplify the centered non-absorption band with a gain up to 26.02 dB. These results reveal that the shift of the novel radiation is determined by the frequency of the non-absorption band near the absorption region, and therefore the emission shifts can be modulated by changing the absorption spectrum. When used in fiber lasers, the BPAWR-SACM process may help to achieve tunability. Designable spatially coherent frequency conversion by synergistic effect of phonon broadening and self-absorption modes in high-entropy glass system.
We propose a theoretical scheme for creating a two-dimensional Electromagnetically Induced Grating in a three-level Λ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\Lambda $$\end{document}-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.
Graphene exhibits remarkable optical and electronic properties when interacts with electromagnetic field. These properties play a vital role in a broad range of applications, such as, optical communication, optical storage, biomedical imaging and security purposes. Based on electromagnetically induced grating (EIG), we study lensless holographic imaging via quantized energy levels of two-dimensional (2D) monolayer graphene model. We observe that by exploiting electromagnetically induced grating (EIG), holographic interference patterns via electromagnetically induced classical holographic imaging (EICHI) and, non locally, electromagnetically induced quantum holographic imaging (EIQHI) can be obtained in the infrared range (THz) of the spectrum. We notice that for EIQHI one can obtain image magnification using monolayer graphene via manipulation of certain controllable parameters. The scheme provides an experimentally viable option for the classical and quantum mechanical holographic imaging and possibilities for the design of graphene-based quantum mechanical devices which can have many applications.
This paper hints at the Goos–Hänchen shift properties of a cavity containing an ensemble of atoms using a four-level atomic system involving a Rydberg state. By means of the stationary phase theory and density matrix formalism in quantum optics, we study theoretically the Goos–Hänchen shifts in both reflected and transmitted light beams. It is realized that as a result of the interaction between Rydberg and excited states in such a four-level atom–light coupling scheme the maximum positive and negative Goos–Hänchen shifts can be obtained in reflected and transmitted light beams owning to the effect of the Rydberg electromagnetically induced transparency (EIT) or Rydberg electromagnetically induced absorption. In particular, when the switching field is absent and the Rydberg EIT is dominant in the medium, a giant Goos–Hänchen shift can be achieved for both reflected and transmitted light beams.
Entangled photon states attract tremendous interest as the most vivid manifestation of nonlocality of
quantum mechanics and also for emerging applications in quantum information. Here we propose a
mechanism of generation of polarization-entangled photons, which is based on the nonlinear optical
interaction (four-wave mixing) in graphene placed in a magnetic field. Unique properties of quantized
electron states in a magnetized graphene and optical selection rules near the Dirac point give rise to a giant
optical nonlinearity and a high rate of photon production in the mid- or far-infrared range. A similar
mechanism of photon entanglement may exist in topological insulators where the surface states have a
Dirac-cone dispersion and demonstrate similar properties of magneto-optical absorption.
The solution of input-output curves in an optical ring cavity containing Landau-quantized graphene is theoretically investigated taking the advantage of density-matrix method. It is found that under the action of strong magnetic and infrared laser fields, one can efficiently reduce the threshold of the onset of optical bistability (OB) at resonance condition. At non-resonance condition, we observed that graphene metamaterial can support the possibility to obtain optical multistability
(OM), which is more practical in all-optical switching or coding elements. We present an analytical approach to elucidate our simulations. Due to very high infrared optical nonlinearity of graphene stemming from very unique and unusual properties of quantized Landau levels near the Dirac point, such controllability on OB and OM may provide new technological possibilities in solid state quantum information science.
In this letter, we show the possibility of controlling the optical bistability and group index switching in graphene under the action of strong magnetic and infrared laser fields. By using quantum-mechanical density matrix formalism, we obtain the equations of motion that govern the optical response of graphene in strong magnetic and optical fields. We found that by properly choosing the parameters of the system, the bistable behaviors and group velocity can be controlled. These results may have potential applications in telecommunication and optical information processing.
We investigate a type of matched infrared soliton pairs based on four-wave mixng (FWM) in Landau-quantized graphene by using density-matrix method and perturbation theory. The linear and nonlinear dynamical properties of the graphene system are first discussed, and, in particular, we focus on the signatures of nonlinear optical response. Then we present analytical solutions for the fundamental bright and dark solitons, as well as bright two-soliton, which are in good agreement with the results of numerical simulations. Moreover, due to the unusual dispersion relation and chiral character of electron states, we find that the matched spatial soliton pairs can propagate through a two-dimensional (2D) crystal of graphene and their carrier frequencies are adjustable within the infrared frequency regimes. Our proposed scheme may provide a route to explore the applications of matched infrared soliton pairs in telecommunication and optical information processing.
Unusual dispersion relation of graphene nanoribbons for electrons can lead to an exceptionally strong optical response in the infrared regime and exhibits a very good tunable frequency. According to quantum optics and solid-material scientific principles, here we show the possibility to generate ultraslow infrared bright and dark solitons in graphene under the action of strong magnetic and infrared laser fields. By means of quantum-mechanical density-matrix formalism, we derive the equations of motion that govern the nonlinear evolution of the probe-pulse envelope in this scheme. It is found that, by properly choosing the parameters of the system, the formation and ultraslow propagation of infrared spatial solitons originate from the balance between nonlinear effects and the dispersion properties of the graphene under infrared excitation. Moreover, the unique electronic properties and selection rules near the Dirac point provide more freedom for us to study the linear and nonlinear dynamical responses of the photonics and graphene system. These results may have potential applications in telecommunication and optical information processing.
We analyze the electromagnetically induced transparency (EIT) in V-, {lambda}-, and cascade-type schemes in a time-dependent way via the Schroedinger-Maxwell formalism. We derive explicitly the analytical expressions of the space-time dependent probe field, the corresponding phase shift, absorption or amplification, group velocity, and group velocity dispersion for all the three schemes. These simple analytical expressions not only demonstrate explicitly the similarities and essential differences of the three schemes but also provide a convenient basis for investigating how the many-body effects in solids modify the magnitude, spectral shape, and space and time dependence of EIT and EIT-related quantum coherence phenomena.
Graphene placed in a magnetic field possesses an extremely high mid/far-infrared optical nonlinearity originating from its unusual band structure and selection rules for the optical transitions near the Dirac point. Here, we study the linear and nonlinear optical response of graphene in strong magnetic and optical fields using a quantum-mechanical density-matrix formalism. We calculate the power of the coherent terahertz radiation generated as a result of the four-wave mixing in graphene. We show that even one monolayer of graphene gives rise to an appreciable nonlinear frequency conversion efficiency and Raman gain for modest intensities of the incident infrared radiation.
We perform a time-dependent analysis of four-wave mixing (FWM) in a double-Λ system in an ultraslow-propagation regime and obtain the analytical expressions of pulsed probe laser, FWM-generated pulse, phase shifts and absorption coefficients, group velocities, and FWM efficiency. With these analytical expressions, we show that an efficiently generated FWM field can acquire the same ultraslow group velocity (Vg∕c∼10−4–10−5) and pulse shape of a probe pump and that the maximum FWM efficiency is greater than 25%, which is orders of magnitude larger than previous FWM schemes in the ultraslow-propagation regime.
We analyze a lifetime-broadened four-state, ladder-type four-wave mixing (FWM) scheme in the context of optical soliton formation. We show that a pulsed probe field and a pulsed FWM field of considerably different frequency can evolve into a pair of matched solitons with the same temporal shape and ultraslow group velocity $({V}_{g}∕c$\sim${}{10}^{$-${}3})$, i.e., two-color ultraslow optical solitons. In addition, we show regimes where two-color superluminal $({V}_{g}∕c<0)$ optical soliton propagation may occur.
We analyze a four-wave-mixing (FWM) scheme in a five-level atomic system based on electromagnetically induced transparency (EIT). We show that EIT suppresses both two-photon and three-photon absorptions in the FWM scheme and enables the four-wave mixing to proceed through real, resonant intermediate states without absorption loss. The scheme results in a several orders of magnitude increase in the FWM efficiency in comparison with a recent scheme [Phys. Rev. Lett. 88, 143902 (2002)] and may be used for generating short-wavelength radiation at low pump intensities.
We investigate the nonlinear dynamics of four-wave mixing in molecular magnets, and show that the matched and coupled electromagnetic soliton pairs can be formed in molecular magnets via a four-wave mixing. It is shown that both bright and dark soliton pairs can propagate through a crystal of molecular magnets and their carrier frequencies are adjustable within the terahertz and sub-terahertz frequency regimes.
The spread and attenuation of the significant probe field caused due to group velocity dispersion which can be precisely balanced by the Kerr nonlinear effect was demonstrated. The interplay between the dispersion and nonlinear effects resulted in the formation of optical solitons that traverse the cold atomic medium with ultraslow group velocities. It was observed that the ultraslow optical solitons might occur in inhomogeneously broadened media such as warm vapors and solid media such as optical waveguide structures. It was found that the optical soliton propagation technique could be an effective way to achieve large nonlinear phase shift, while maintaining shape invariant propagation of the optical field.
Pancharatnam—Berry (PB) phase metasurface, as a special class of gradient metasurfaces, has been paid much attention owing to the robust performance for phase control of circularly polarized waves. Herein, we present an element-based polarizer for the first step, which enables the incident electromagnetic waves into the cross-polarized waves with the relative bandwidth of 71%, and the polarization conversion ratio exceeds 90% at 6.9–14.5 GHz. Then an eight-elements coding polarizer based on the PB phase is presented for the applications on beam control and radar cross section reduction. The simulated values indicate that the reduction of radar cross section is more than 10 dB at 6–16 GHz. Our work reveals the availability of manipulating the waves, beamforming in communication systems and electromagnetic stealth, and so on.
We investigate the interaction of laser pulses carrying orbital angular momentum (OAM) with a symmetry-broken ladder-type quantum coupling scheme involving three internal states. A weak probe beam acts on the lower leg of the ladder scheme, while a control beam of higher intensity drives the upper leg. In contrast to natural atoms, such a model with broken symmetry allows generating a sum-frequency signal beam between the most upper and lower quantum states, forming a cyclic closed-loop configuration of light-matter interaction. We propose situations for the efficient transfer of optical vortices to the generated signal beam via a nonlinear three-wave mixing process. It is demonstrated that the exchange process can occur both in the electromagnetically induced transparency (EIT) and the Autler-Townes splitting (ATS) regimes. The transition between the EIT and ATS conversion schemes can smoothly happen by simply tuning the knob of the control field. It is shown that the ATS regime is considerably more favorable than the EIT to achieve maximum energy conversion efficiency between light beams carrying the OAM. The results may provide an applications-based perspective to the ongoing research centered on vortex conversion-based comparisons between the ATS and EIT.
We study the effect of orbital angular momentum transfer between optical fields
in a semiconductor quantum well waveguide with four energy levels in a closed-loop configuration via four-wave mixing. The waveguide is driven by two strong control fields and two weak probe fields. We consider three different cases for the light-matter interaction in order to efficiently exchange optical vortices. In the first two cases, the system is initially prepared in either a lower electromagnetically induced transparency or a coherent population trapping state, while the last case prepares the system in an upper state, enabling to induce the electron spin coherence. We find that for appropriate parameters and via the spin coherence effect, the efficiency of four-wave mixing is much higher in the quantum well waveguide. Working in the electron spin coherence regime, we then study the light-matter interaction under the situation where only one of the control fields has an optical vortex. The orbital angular momentum of the vortex control beam can be efficiently transferred to a generated probe field via the spin coherence. We also show that the spatially dependent optical effects of the waveguide can be strongly modified by the electron spin coherence.
A quantum optical model involving a plasmonic nanostructure (PN) is proposed for controlling
the diffraction efficiency of an electromagnetically induced grating in a four-level quantum system. By
tuning the distance between the PN and the four-level quantum system, diffraction efficiency can be
adjusted and energy can be transferred from zero order to higher orders. Moreover, due to the presence of
the PN, the medium becomes phase-dependent and therefore, phase control of grating can be possible by
changing the relative phase of the applied fields.
We discuss the optical bistability and multistability properties of incident light on a unidirectional ring cavity consisting of a hybrid semiconductor quantum dot-metal nanoparticle system driven by coupling and incoherent pumping fields. We consider the quantum dot system as a three-level V-type configuration which is placed near the metallic nanoparticle. We realize that the threshold of optical bistability and optical multistability can be controlled by tuning the center-to-center distance between quantum dots and metallic nanoparticles. Moreover, the effect of incoherent pumping field on optical bistability and optical multistability has been discussed for different distances between quantum dots and metallic nanoparticles.
In this paper, we discuss Goos-Hänchen (GH) shifts of both reflected and transmitted light beams through a cavity containing single-layer graphene nanostructures. The Landau levels of a single layer graphene medium under a strong magnetic field can interact with infrared and terahertz signal radiation. Therefore, the GH shifts in both reflected and transmitted light beams can be obtained in the infrared and terahertz regions of radiation. We have realized that by controlling some adjustable parameters of the system, such as frequency detuning of applied fields, the Rabi frequency of a coupling field and the polarization of coupling light, the GH shifts can be manipulated in the infrared and terahertz regions. Moreover, the thickness of the intracavity medium is also considered as an important parameter on the behavior of GH shifts spectra.
In this letter, the phase control of optical bistability and multistability in a ring cavity doped with a four-level graphene nanostructure in infrared regions are discussed. Due to the unusual dispersion relation in graphene nanoribbons, electrons can lead to an exceptionally strong optical response in the infrared and terahertz regions. We show that by adjusting the intensities and relative phase of infrared laser fields, the threshold intensity and hysteresis loop can be manipulated efficiently. The effect of the electronic cooperation parameter, which is directly proportional to the electron concentration and the length of the graphene sample, is also discussed. Our proposed model may be useful for the next generation of all-optical systems and information processing in nanoscale devices.
In this letter, controllable optical bistability (OB) and optical multistability (OM) in a defect slab doped with a single-layer graphene nanostructure are proposed. Our numerical results show that it is easy to control OB by Rabi frequencies of coupling fields, detuning of coherent fields, and relative phase of applied fields. Moreover, the thickness effect of the slab is considered as a new parameter for controlling the OB behaviors. It is found that the transition from OB to OM or vice versa can be made possible by the thickness of the slab and relative phase of the applied fields. We hope that our results will have potential applications in quantum information science and technology based nanoscale devices.
We theoretically investigate the behaviour of optical bistability (OB) and optical multistability (OM) in a graphene monolayer system driven by an elliptically polarized control field and a right-hand circularly polarized probe field. Our numerical results show that it is easy to realize the transition from OB to OM or vice versa by adjusting the frequency detunings of the probe field and the control field, as well as the polarization-dependent phase difference between the two components of the control laser field. The influences of the intensity of the control field and the cooperation parameter on the OB behavior are also discussed in detail. These results may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.
The behavior of the Goos-Hänchen (GH) shifts of the reflected and transmitted probe and signal pulses through a cavity containing four-level GaAs/AlGaAs multiple quantum wells with 15 periods of 17.5 nm GaAs wells and 15-nm Al0.3Ga0.7As barriers is theoretically discussed. The biexciton coherence set up by two coupling fields can induce the destructive interference to control the absorption and gain properties of probe field under appropriate conditions. It is realized that for the specific values of the intensities and the relative phase of applied fields, the simultaneous negative or positive GH shift in the transmitted and reflected light beam can be obtained via amplification in a probe light. It is found that by adjusting the controllable parameters, the GH shifts can be switched between the large positive and negative values in the medium. Moreover, the effect of exciton spin relaxation on the GH shift has also been discussed. We find that the exciton spin relaxation can manipulate the behavior of GH shift in the reflected and transmitted probe beam through the cavity. We show that by controlling the incident angles of probe beam and under certain conditions, the GH shifts in the reflected and transmitted probe beams can become either negative or positive corresponding to the superluminal or subluminal light propagation. Our proposed model may supply a new prospect in technological applications for the light amplification in optical sensors working on quantum coherence impacts in solid-state systems.
Phase-dependent and switchable transmission and group velocity are achieved for a light beam traveling through a one-dimensional photonic crystal containing a dispersive layer. By proper selection of phase difference between probe and coupling fields, the quantum interference in dopant atoms to the defect layer leads to controlling of delay time of transmitted and reflected light. This way, simultaneous subluminal transmission and reflection are achievable. We also found that transmission of one-dimensional photonic crystals is actively controllable in a wide range only by controlling the characteristics of incident light with no need for altering the effective indices or thicknesses of layers.
In this paper, we theoretically investigate transmission and reflection properties of incident light through dielectric medium doped by GaAs/AlGaAs multiple quantum wells with 15 periods of 17.5 nm GaAs wells and 15-nm Al0.3 Ga0.7As barriers, grown by metal organic chemical vapor deposition. The destructive quantum interference is set up by a control pulse that couples to a resonance of biexcitons. We found that many-particle interactions such as biexciton binding energy and biexciton decoherence which are inherent in semiconductors can affect the transmission and reflection properties of incident light on the slab. We have also shown that simultaneous subluminal or superluminal transmission, reflection can be achievable at different frequencies of probe field.
In this paper, phase control of Kerr nonlinearity in a GsAs multiple quantum wells (MQWs) with 17.5 nm GaAs wells and 15 nm Al0.3Ga0.7 barriers is studied. The role of exciton spin relaxation and biexciton binding energy as well as Rabi frequencies of applied fields on phase control of Kerr nonlinearity and nonlinear absorption is also discussed. It is found that exciton spin relaxation (spin decoherence) and biexciton binding energy which resulted from many-particle interaction in semiconductors have essential roles in producing giant Kerr nonlinearity with nonlinear amplification for some values of relative phase between applied fields. Our study provides a suitable treatment for the next generation of all-optical systems in semiconductor nanostructures. Moreover, we hope that our theoretical work may be helpful for the future experimental works based on many-particle interaction in the semiconductors.
We investigate theoretically the optical bistability of reflection at the interface between graphene and Kerr-type nonlinear substrates. We derive a simple procedure to calculate the nonlinear reflectivity with graphene, and discuss the influence of the graphene sheets on the hysteretic response of the TM-polarization reflected light. It is found that the bistable behavior of the reflected light can be electrically controlled via suitably varying the applied voltage on the graphene. In THz, the bistable thresholds can be lowered markedly by increasing the Fermi energy. However, in near-infrared frequency, it requires multiple graphene layers to exhibit significant influence on the bistable thresholds.
Propagation of Gaussian pulse in a defect dielectric medium in the presence of spin coherence is theoretically investigated. We consider a dielectric slab doped with semiconductor quantum well nanostructure. We show that the reflected and transmitted pulses can be tuned from subluminal to superluminal by changing spin coherence in a slab. Our result predicts that the group velocity of the reflected and transmitted pulses in different wavelengths depend on the thickness of the slab, intensity of the coupling field and relative phase between applied fields.
We investigate the one- and two-dimensional atom localization behaviors via spontaneous emission in a coherently driven five-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of atom localization behaviors can be significantly improved via adjusting the system parameters. More importantly, the two-dimensional atom localization patterns reveal that the maximal probability of finding an atom within the sub-wavelength domain of the standing waves can reach unity when the corresponding conditions are satisfied. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization.
In this paper, transmission and reflection properties of incident pulse
in a dielectric slab which doped by quantum dot nanostructure via
electron tunneling is studied. It is shown that by using the electron
tunneling in a quantum dot, the transmission and reflection coefficients
can be controlled at different wavelengths. Therefore, this model can be
used as an all-optical filter which is suitable for next generation of
all optical communication systems.
For a three-level semiconductor quantum well system with a closed-loop configuration, we find that, owing to the quantum interference and coherence, the large enhancement of probe gain can be achieved under appropriate conditions. In particular, the relative phase of the applied fields plays an important role in realizing the large gain of the probe field. Our study is much more practical than its atomic counterpart due to its flexible design and the wide adjustable parameters. Thus, it may provide some possibilities for obtaining potential applications in solid-state quantum computation and quantum communication.
We present a simple scheme of atom localization in a subwavelength domain via manipulation of probe absorption spectrum in a four-level atomic system. By applying two orthogonal standing-wave fields, the localization peak position and number as well as the conditional position probability can be controlled by the intensities and detunings of optical fields, and the sub-half-wavelength atom localization is also observed. More importantly, there is 100% detecting probability of the atom in the subwavelength domain when the corresponding conditions are satisfied.
We theoretically investigate the hybrid absorptive–dispersive optical bistability and multistability in a four-level inverted-Y quantum well system inside a unidirectional ring cavity. We find that the coupling field, the pumping field as well as the cycling field can affect the optical bistability and multistability dramatically, which can be used to manipulate efficiently the threshold intensity and the hysteresis loop. The effects of the relative phase and the electronic cooperation parameter on the OB and OM are also studied. Our study is much more practical than its atomic counterpart due to its flexible design and the wide adjustable parameters. Thus, it may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.
We present quantum-mechanical density-matrix formalism for calculating the
nonlinear optical response of magnetized graphene, valid for arbitrarily strong
magnetic and optical fields. We show that magnetized graphene possesses by far
the highest third-order optical nonlinearity among all known materials. The
giant nonlinearity originates from unique electronic properties and selection
rules near the Dirac point. As a result, even one monolayer of graphene gives
rise to appreciable nonlinear frequency conversion efficiency for incident
infrared radiation.
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