共查询到20条相似文献,搜索用时 15 毫秒
1.
The giant enhancement of Kerr nonlinearity in a four-level inverted-Y atomic system is investigated theoretically. Compared with that generated in a generic three-level system, the Kerr nonlinearity can be enhanced by several orders of magnitude with vanishing linear absorption. The physical mechanism leading to the giant enhancement of Kerr nonlinearity is also discussed. 相似文献
2.
空场诱导相干性对倒转Y型四能级原子系统中单光子和双光子吸收性质的影响 总被引:1,自引:0,他引:1
当倒转Y-型四能级原子的两基态能级邻近简并时,连接基态的两个跃迁路径与同一个真空场辐射场相互作用导致的量子干涉效应便产生了空场诱导相干性.空场诱导相干性能使倒转Y-型四能级原子在共振点的单光子和双光子电磁诱导透明现象减弱,而在其他失谐量处产生单光子增益现象。同时,外加相干光场的相对相位对原子的吸收性质有重要的影响. 相似文献
3.
Jun Kou Ren-Gang Wan Shang-Qi Kuang Li Jiang Liang Zhang Zhi-Hui Kang Hai-Hua Wang Jin-Yue Gao 《Optics Communications》2011,284(6):1603-1607
The electromagnetically induced transparency (EIT) and its dispersion properties in a four-level inverted-Y atomic system are investigated. The absorption spectrum of a weak probe field shows two EIT windows (dark resonances) whose location, width, and depth can be controlled by manipulating the parameters of the coupling fields; the corresponding dispersion properties are also measured by using a Mach-Zehnder interferometer. The experimental measurements agree well with the theoretical calculations. This kind of system can find important applications in two-channel quantum communication and information storage. 相似文献
4.
Wen-juan Jiang Jian-ping Song Huai-bin Zheng Bao-yin Yin 《Optics Communications》2009,282(1):101-1839
A theoretical investigation is carried out into the effect of spontaneously generated coherence (SGC) on Kerr nonlinearity of a four-level N-type system. It’s found that the Kerr nonlinearity can be obviously enhanced with SGC present. We attribute the enhancement of Kerr nonlinearity mainly to the generation of extra coherences induced by the superposition of the two SGC channels, and when the superposition is controlled by the interference between two SGC channels properly, the maximal Kerr nonlinearity does not only enter the electromagnetically induced transparency window as the spontaneous generated coherences intensify, but also gets enhanced about 10 times with very large SGC coefficients than that with no SGC effect. 相似文献
5.
Yan Zhang 《Physics letters. A》2010,374(8):1088-661
We study and compare the steady and transient optical responses of a four-level system and a three-level system, which are dressed by two and three laser fields, respectively. In the three-level system, a transmissivity window (a reflectivity platform) may be induced on the probe resonance by a traveling-wave (standing-wave) coupling field. In the four-level system, both transmissivity window and reflectivity platform are remarkably modified when a traveling-wave driving field is applied on two-photon resonance with the probe, but change little when the traveling-wave driving field is largely two-photon detuned. This implies that the four-level system can be safely treated as a three-level one in certain frequency regions of interest. Transient behaviors of atomic coherence on the probe resonance are also examined in both three-level and four-level systems to further confirm this conclusion. Our new findings are beneficial to achieve a novel all-optical routing scheme by simultaneously creating a transmissivity window and a reflectivity platform on a single resonance, and may also be used to simplify theoretical treatments in the situations where numerical calculations are complicated and intractable in the presence of at least one standing-wave field. 相似文献
6.
The dressed four- and six-wave mixings in a V-type four-level system
are considered. Under two different dressed conditions, two- and
three-photon resonant Autler--Townes splittings, accompanied by
enhancement and suppression of wave mixing signal, are obtained
analytically. Meanwhile, an electromagnetic induced transparency of
multi-wave mixing is presented, which shows multiple peaks and
asymmetric effects caused by one-photon, two-photon and three-photon
resonances, separately. The slow light propagation multiple region of
multi-wave mixing signal is also obtained. 相似文献
7.
8.
Chao Hang 《Physics letters. A》2008,372(17):3129-3135
We investigate possible formation and propagation of localized, shape-preserving nonlinear optical pulse in a resonant, lifetime-broadened four-level tripod atomic system via electromagnetically induced transparency (EIT). We prove both analytically and numerically that although in anomalous dispersion regimes near resonance a superluminal optical soliton may appear, such soliton suffers serious absorption. However, by choosing appropriate parameters to make the system work in normal dispersion regimes and within an EIT transparency window, ultraslow optical solitons with very low light intensity can form and propagate stably in the system. 相似文献
9.
Y.-X. Ping B. Zhang Z. Cheng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(1):175-180
The generation of continuous variable entanglement via
atomic coherence in a two-mode three-level cascade atomic system
is discussed according to the entanglement criterion proposed by
Duan et al. [Phys. Rev. Lett. 84, 2722 (2000)].
Atomic coherence between the top and bottom levels is induced with
two photons of a strong external pump field. It shows that
entanglement for the two-mode field in the cavity can be generated
under certain conditions. Moreover, by means of the input-output
theory, we show that the two-mode entanglement could also be
approached at the output. 相似文献
10.
11.
An analytical model for cross-Kerr nonlinearity in a four-level N-type atomic system with Doppler broadening 下载免费PDF全文
Dinh Xuan Khoa Nguyen Huy Bang Nguyen Le Thuy An Nguyen Van Phu Le Van Doai 《中国物理 B》2022,31(2):24201-024201
We present an analytical model for cross-Kerr nonlinear coefficient in a four-level N-type atomic medium under Doppler broadening.The model is applied to87 Rb atoms to analyze the dependence of the cross-Kerr nonlinear coefficient on the external light field and the temperature of atomic vapor.The analysis shows that in the absence of electromagnetically induced transparency(EIT)the cross-Kerr nonlinear coefficient is zero,but it is significantly enhanced when the EIT is established.It means that the cross-Kerr effect can be turned on/off when the external light field is on or off.Simultaneously,the amplitude and the sign of the cross-Kerr nonlinear coefficient are easily changed according to the intensity and frequency of the external light field.The amplitude of the cross-Kerr nonlinear coefficient remarkably decreases when the temperature of atomic medium increases.The analytical model can be convenient to fit experimental observations and applied to photonic devices. 相似文献
12.
13.
《Physics letters. A》2020,384(11):126234
The magnitude and sign of self-Kerr nonlinear coefficient in a degenerate two-level inhomogeneously broadened medium are simply controlled by an external magnetic field. By changing the external magnetic field we can switch a negative peak of Kerr nonlinear coefficient into a positive peak and vice versa, and transform a zero value of Kerr nonlinear coefficient into a positive or negative peak in resonant region. Such a controllable Kerr nonlinear coefficient can be used to manipulate the working characteristics of photonic devices such as optical switches and bistable elements. 相似文献
14.
15.
X.-J. Liu H. Jing M.-L. Ge 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):297-303
We examine in detail the quantum memory technique for photons in a
double Λ atomic ensemble in this work. The novel
application of the present technique to create two different
quantum probe fields as well as entangled states of them is
proposed. A larger zero-degeneracy class besides dark-state
subspace is investigated and the adiabatic condition is confirmed
in the present model. We extend the single-mode quantum memory
technique to the case with multi-mode probe fields, and reveal the
exact pulse matching phenomenon between two quantized pulses in
the present system. 相似文献
16.
General formulae for the transient evolution of the susceptibility (absorption) induced by the quantum interference effect in a four-level N-type EIT medium is presented. The influence of the signal light on the transient susceptibility for the probe beam is studied for two typical cases when the strength of the coupling beam is much greater or less than that of the signal field. An interesting level reciprocity relationship between these two cases is found. 相似文献
17.
Yaqi Yan Zhenkun Wu Jinhai Si Lihe Yan Yiqi Zhang Chenzhi Yuan Jia Sun Yanpeng Zhang 《Annals of Physics》2013
We theoretically deduce the macroscopic symmetry constraints for arbitrary odd-order nonlinear susceptibilities in homogeneous media including atomic vapors for the first time. After theoretically calculating the expressions using a semiclassical method, we demonstrate that the expressions for third- and fifth-order nonlinear susceptibilities for undressed and dressed four- and six-wave mixing (FWM and SWM) in atomic vapors satisfy the macroscopic symmetry constraints. We experimentally demonstrate consistence between the macroscopic symmetry constraints and the semiclassical expressions for atomic vapors by observing polarization control of FWM and SWM processes. The experimental results are in reasonable agreement with our theoretical calculations. 相似文献
18.
准Λ型4能级系统具有电磁诱导吸收(EIA)和电磁诱导透明(EIT)两种特性.准Λ型4能级系统包括两个基态精细结构能级和两个激发态精细结构能级,除光学耦合场和探测场外,附加了一个射频场作用于两个激发态精细结构能级之间.若对此系统进行拓展,在两个基态精细结构能级之间引入一个驱动场,则构成4场作用下的闭合Λ型4能级系统.本文对新引进的驱动场的作用规律进行了重点研究.研究结果表明,当驱动场和射频场的Rabi频率满足不同关系时,系统呈现EIA或EIT两种不同特性,探测吸收曲线的整体轮廓也随之改变. 相似文献
19.
Luís E.E. de Araujo Silvânia A. Carvalho A.A. Soares Daniel Pereira 《Optics Communications》2008,281(4):626-632
We performed two-color spectroscopy of the (4s2) 1S0 → (4s4p) 1P1 → (4p2) 1D2 calcium atomic transition and observed velocity-selective optical pumping in a calcium hollow cathode lamp by means of optogalvanic detection. The optical pumping signature in optogalvanic detection is compared to that of fluorescence and transmission detections. The optogalvanic technique is found to be a very sensitive method of detecting optical pumping and could be used in distinguishing optical pumping from electromagnetically induced transparency. 相似文献
20.
We observe linewidths below the natural linewidth for a probe laser on a degenerate two-level F → F′ transition, when the same transition is driven by a strong control laser. We take advantage of the fact that each level of the transition is made of multiple magnetic sublevels, and use the phenomenon of electromagnetically induced transparency (EIT) or absorption (EIA) in multilevel systems. Optical pumping by the control laser redistributes the population so that only a few sublevels contribute to the probe absorption, an explanation which is verified by a density-matrix analysis of the relevant sublevels. We observe more than a factor of 3 reduction in linewidth in the D2 line of Rb in room-temperature vapor. Such subnatural features vastly increase the scope of applications of EIT, such as high-resolution spectroscopy and tighter locking of lasers to atomic transitions, since it is not always possible to find a suitable third level. 相似文献