Incoherent Pumping Field Research Articles

Transient properties in a resonant ladder-type atomic system with vacuum-induced coherence and incoherent pumping

The transient absorption and population in a resonant ladder-type atomic system with or without an incoherent pumping field are theoretically investigated. We find that the vacuum-induced coherence and the relative phase between probe and coupling fields can clearly affect the transient absorption (gain) properties, but the steady-state value of the probe absorption (gain) is remarkably dependent on the incoherent pumping. And the steady population distribution is sensitive to the incoherent pumping and insensitive to the relative phase. Additionally, it is shown that the lasing with inversion can be reached with the incoherent pumping.

Numerical analysis of absorption–amplification response in an optical fiber

We investigated the transient and steady-state processes of a probe field in an optical fiber. It is found that the nonlinear processes can be easily controlled via the coherent field and incoherent pumping field. The underlying mechanisms are much more practical than those in atomic systems, which may provide some possibilities for technological applications in optical-fiber communication.

High refractive index without absorption via spontaneously generated coherence and incoherent pumping

We studied a closed three-level V-type system with two near-degenerate excited levels in the presence of an incoherent pumping field. Quantum interferences of the two-decay channels lead to the achievement of the high index of refraction without absorption via spontaneously generated coherence. We use the exact analytical formula of the refractive index derived by us in a recent paper. We found that the high refractive index varies very much with the angle between the two dipole moments and evidently with the detuning of the coupling field.

Some optical properties of four-level media via coherent and incoherent pumping fields

The optical properties of a four-level atomic system via coherent and incoherent pumping fields are investigated. The giant Kerr nonlinearity with reduced linear and nonlinear absorption, which has a major role in decreasing the threshold of optical bistability (OB), can be obtained with subluminal light propagation via adjusting the intensities of coupling fields. An incoherent pumping field is noticed to be an extra parameter to reduce the threshold of OB and multistability, and it can be used as an effective parameter in producing lasing with or without population inversion. In this model, optical multistability is achieved simply by tuning the intensity of coupling laser fields. Furthermore, it is shown that the subluminal and the superluminal light propagation can be obtained by appropriate values of the incoherent pumping rate.

Effect of Quantum Interference from Incoherent Pumping Field and Spontaneous Emission on Controlling the Optical Bistability and Multi-Stability

Optical bistability (OB) and optical multi-stability (OM) of a four-level Λ-type atomic system with two fold lower levels inside a unidirectional ring cavity is investigated. The effect of quantum interference arising from spontaneous emission and incoherent pumping on OB and OM is discussed. It is found that the threshold of OB and OM can be controlled by quantum interference mechanisms. In addition intensity of coupling field and the rate of an incoherent pumping field on behavior of OB and OM are then discussed.

Negative refraction with tunable absorption in an active dense gas of atoms

The applications of negative index materials (NIM) are currently severely limited by absorption. Subsequent to improvements of metamaterial design, it has been suggested that dense gases of atoms could form NIM with negligible loss. In such gases, the low absorption is facilitated by quantum interference. In this paper, we show that additional gain mechanisms can be used to tune and effectively remove absorption in a dense gas NIM. In our setup, the atoms are coherently prepared by control laser fields, and further driven by a weak incoherent pump field to induce gain. We employ nonlinear optical Bloch equations to analyze the optical response. Metastable neon was identified as a suitable experimental candidate at infrared frequencies to implement a lossless active negative index material.

Lasing without inversion in a four-level diamond system

We study the lasing without inversion in a four-level diamond configuration in the case of incoherent pumping field within the framework of the bare-state basis. With the strong fields limit, we obtain the approximate steady-state solution, and discuss the dependence of population distribution and system gain on probe detuning and auxiliary field Rabi frequency.

Hartman effect in one-dimensional photonic crystal doped by Λ-type three-level atoms

Hartman effect in one-dimensional photonic crystal with a defect layer doped by Λ-type three-level atoms is theoretically discussed. It is found that the phase time delay can be controlled from positive to negative (or vice versa) just by the intensity of coupling field. Furthermore, in the presence of quantum interference or an incoherent pump field the medium becomes completely phase dependent. Therefore, the phase time delay can be switched from negative to positive just by adjusting the relative phase of the applied fields and the rate of an incoherent pump field.

LASING WITH AND WITHOUT POPULATION INVERSION IN A QUANTUM DOT NANOSTRUCTURE VIA AN INCOHERENT PUMPING FIELD

The effect of incoherent pumping field on absorption spectrum and population inversion in a four-level quantum dot nanostructure are investigated. It is found that with incoherent pumping field the probe field absorption can be converted to probe field gain. Also, it is found that with combine effect of incoherent pumping field and electron tunneling the lasing can be obtained in the absence or presence of population inversion.

Resonant gain suppression and superluminal group velocity in a multilevel system

We investigate the interaction of an open (N + 1)-level extended V-type atomic system (i.e. a closed (N + 2)-level atomic system) with N coherent laser fields and one incoherent pumping field through both analytical and numerical calculations. Our results show that the system can exhibit multiple resonant gain suppressions via perfect quantum destructive interference, which is usually believed to be absent in closed three-level V system and its extended versions involving more atomic levels, with at most N - 1 transparency windows associated with very steep anomalous dispersions occurring in the system. The superluminal group velocity of the probe-laser pulse with at most N - 1 negative values can also be generated and controlled with little gain or absorption.

Lasing without population inversion in an Er3+-doped YAG crystal

Two atomic models are proposed for an Er3+-doped YAG crystal with application to lasing with and without population inversion. It is shown how an incoherent pumping field and coherent control coupling field can produce a laser in the presence and absence of population inversion.

Subluminal to superluminal light propagation in a V-type three-level atomic system interacting with squeezed vacuum

We study the light propagation properties in a V-type three-level atomic system interacting with two independent broadband squeezed baths. Using the graphic method, the dependences of the absorption and the dispersion of the system on the coupling field strength, the incoherent pumping field strength and the intensity of the squeezed vacuum are analysed. The result shows that the probe pulse propagation can be changed from subluminal to superluminal speed.

Controlling the probe-absorption and -dispersion via quantum interference from incoherent pumping field in a four-level lambda-type system

Absorptive and dispersive properties of a four-level Λ-type atomic system with two fold lower levels are investigated. The effect of quantum interference induced by incoherent pump and spontaneous emission upon the absorption, dispersion, and group index is them discussed. In addition, the rate of an incoherent pump field and the intensity of coupling field on light propagation is also presented.

Incoherent pump influence on the transient gain in a V-type system with spontaneously generated coherence

We study the influence of the incoherent pump field on the transient response of a three-level V-type system with two near-degenerate excited states. In this system due to interaction of the field with the vacuum an interference term appears, the spontaneously generated coherence term. We find that due to the incoherent pump the transient proprieties of the atomic system can be significantly modified. The enhancement of the transient gain can be obtained for proper values of the rate of the incoherent pump field and relative phase between the two fields.

Gain and transmission properties of a probe field in a four-level atomic system

AbstractWe theoretically investigate the absorption–amplification response of the probe field in a four-level cold 87Rb atomic system. It is found that the incoherent pumping fields play very important roles in realizing the amplification of the probe field. The transmission property of the probe field is also studied.

Optical bistability via quantum interference from incoherent pumping and spontaneous emission

We theoretically investigate the optical bistability (OB) in a V-type three-level atomic system confined in a unidirectional ring cavity via incoherent pumping field. It is shown that the threshold of optical bistability can be controlled by the rate of an incoherent pumping field and by interference mechanism arising from the spontaneous emission and incoherent pumping field. We demonstrate that the optical bistability converts to optical multi-stability (OM) by the quantum interference mechanism.

Electron population and optical properties via incoherent pumping fields in semiconductor quantum wells

In a three-level asymmetric semiconductor quantum well system, owing to the effects that result from the incoherent pumping fields, we find that the electron population, absorption and dispersion properties can be efficiently controlled. The results are achieved by applying the two incoherent pumping fields, so they are very different from the conventional schemes that coherent driving fields are used to control the optical properties and electron population. Thus, it may provide some new possibilities for technological applications in solid-state optoelectronics science.

Controlling the optical bistability via quantum interference in a four-level N-type atomic system

We investigate the optical bistability (OB) and optical multi-stability (OM) in a four-level N-type atomic system. The effect of spontaneously generated coherence (SGC) on OB and OM is then discussed. It is found that SGC makes the medium phase dependent, so the optical bistability and multi-stability threshold can be controlled via relative phase between applied fields. We realize that the frequency detuning of probe and coupling fields with the corresponding atomic transition plays an important role in creation OB and OM. Moreover, the effect of laser coupling fields and an incoherent pumping field on reduction of OB and OM threshold is then discussed.

OPTICAL BISTABILITY VIA INCOHERENT PUMPING FIELDS IN SEMICONDUCTOR QUANTUM WELLS

Under the non-resonant condition, we investigated the optical bistability (OB) in a three-level quantum well system inside a unidirectional ring cavity. We find that the incoherent pumping fields and the quantum interference induced by incoherent pumping fields can affect the optical bistability dramatically, which can be used to manipulate efficiently the threshold intensity and the hysteresis loop. These results are achieved by applying the two incoherent pumping fields, so they are very different from the conventional schemes that coherent driving fields are used to control the optical bistability. Thus, it may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.

Control of the probe absorption via incoherent pumping fields in asymmetric semiconductor quantum wells

In a three-level asymmetric semiconductor quantum well system, owing to the effects that result from the incoherent pumping fields, the probe absorption of probe field can be effectively controlled. The result is achieved by applying the two incoherent pumping fields, so it is different from the conventional way in ordinary laser-driven schemes that coherent driving fields are necessary to control the probe absorption. Otherwise, our study is much more practical than its atomic counterpart due to its flexible design and the controllable interference strength. Thus, it may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.