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1.
This paper investigates the control role of the relative phase between the probe and driving fields on the gain, dispersion and populations in an open A system with spontaneously generated coherence (SGC). It shows that by adjusting the value of the relative phase, a change from lasing with inversion to lasing without inversion can be realized; the values and frequency spectrum regions of the inversionless gain and dispersion can be obviously varied; high refractive index with zero absorption and electromagnetically induced transparency can be achieved. It is also found that when the driving field is resonant, the shapes of the dispersion and the gain curves versus the probe detuning are very similar if the relative phase of the dispersion lags π/2 than that of the gain, however for the off-resonant driving field the similarity will disappear; the gain, dispersion and populations are periodical functions of the relative phase, the modulation period is always 2π; the contribution of SGC to the inversionless gain and dispersion is much larger than that of the dynamically induced coherence. 相似文献
2.
提出开放的四能级双驱动场无反转激光系统的理论模型,由电偶极和旋转波近似得到其密度矩阵方程,讨论无反转激光产生的物理机制,利用数值计算结果分析探测场和驱动场失谐对系统无反转激光增益和粒子数差的影响. 相似文献
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Phase control of probe response in an open ladder type system with spontaneously generated coherence
Aiyun Li Hui Ma Xia Tan Yanling Yang Dianmin Tong Xijun Fan 《Optics Communications》2007,280(2):397-403
The control role of the relative phase between the probe and driving fields on the gain and dispersion in an open three-level ladder atomic system with incoherent pumping and spontaneously generated coherence is investigated. It is shown that by adjusting the value of the relative phase, the switching from lasing with inversion to lasing without inversion (LWI) can be realized; high index of the refraction with zero absorption can be achieved. It is also found that when the driving field is on resonance, the dispersion curve versus the probe detuning is very similar to the gain curve if the relative phase corresponding to the dispersion advances π/2 than that corresponding to the gain. LWI gain from the open system is obviously larger than that from corresponding closed system. When the incoherent pumping is absent, the open system can get LWI gain, moreover the gain is larger than that when the incoherent pumping presents for suitable value of the relative phase, but the corresponding closed system exhibits only absorption. In addition, manipulation effects of atomic exit and ratio of the injection rates on phase dependent gain are also analyzed. 相似文献
5.
Z. Ficek J. Seke A.V. Soldatov G. Adam N.N. Bogolubov Jr 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):411-419
We investigate the absorption and dispersion properties of a two-level atom driven by a polychromatic field. The driving field
is composed of a strong resonant (carrier) frequency component and a large number of symmetrically detuned sideband fields
(modulators). A rapid increase in the absorption at the central frequency and the collapse of the response of the system from
multiple frequencies to a single frequency are predicted to occur when the Rabi frequency of the modulating fields is equal
to the Rabi frequency of the carrier field. These are manifestations of the undressing or a disentanglement of the atomic
and driving field states, that leads to a collapse of the atom to its ground state. Our calculation permits consideration
of the question of the undressing of the driven atom by a multiple-modulated field and the predicted spectra offer a method
of observing undressing. Moreover, we find that the absorption and dispersion spectra split into multiplets whose structures
depend on the Rabi frequency of the modulating fields. The spectral features can jump between different resonance frequencies
by changing the Rabi frequency of the modulating fields or their initial phases, which can have potential applications as
a quantum frequency filter.
Received 23 October 2001 and Received in final form 31 January 2002 相似文献
6.
在旋波、慢变振幅近似下,求解考虑了驱动场相位扩散后的系统密度矩阵运动方程,并给出了这个三能级梯型系统稳态线性解析解.利用得到的稳态线性解析解分析驱动场相位扩散是如何影响该系统输出无反转激光的.对稳态线性解析解数值计算的结果显示:由于驱动场相位扩散会导致无反转激光增益减小;即使由于驱动场相位扩散引起的线宽足够大,在该系统中仍能够获得无反转激光;线宽往往是破坏无反转激光产生和折射率的提高;因驱动场相位扩散导致无反转激光增益的减小,并不是总能够通过增大驱动场的Rabi频率得到补偿. 相似文献
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M. Sahrai R. Etemadpour M. Mahmoudi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,59(3):463-471
The dispersion and the absorption properties of a driven four-level Λ-type atomic system is investigated. It is found that the interaction of double-dark states lead to controllable group velocity
of the weak probe field by the intensity of driving field and the relative phase between applied fields. Moreover, the transient
dispersion, absorption and the group index are also discussed. The required switching time for switching the group velocity
of a weak probe field from subluminal to superluminal pulse propagation is then discussed. 相似文献
9.
开放的非共振梯型无粒子数反转激光系统非线性增益与色散的研究 总被引:5,自引:1,他引:4
本文给出了开放的非共振ladder型三能级无粒子数反转激光系统的非线性精确解,利用数值计算结果讨论了系统各参量的变化对激光场的增益和色散的影响.作者得到以下结论:当探测激光场和驱动场都共振时,无论其他参量如何变化,色散为零.当仅有探测场失谐(驱动场失谐)时,增益和色散随探测场失谐(驱动场失谐)的变化曲线分别具有偶对称性和中心对称性,当探测场和驱动场皆失谐时,这种对称性消失;适当调节探测激光场或(和)驱动场的失谐可获得最大或较大的无粒子数反转激光增益和无吸收高色散.增益和色散(粒子数差绝对值)随原子注入速率之比的增加单调增加(单调减小),且原子退出速率越大增加(减小)得越快.在探测场和驱动场适当失谐的情况下,保持系统其他参量不变,非相干泵浦速率只有在一定范围内取值时,才能获得无粒子数反转激光增益,并存在一个增益极大值.改变探测场或驱动场Rabi频率对无粒子数反转激光增益的影响与非相干泵浦速率改变时的情况类似. 相似文献
10.
运用密度矩阵理论,研究了在外加相干耦合场作用下∧型四能级系统的吸收和色散特性。数值模拟表明:通过调节外加相干场的拉比频率强度,该系统可以单重、双重电磁诱导光透明现象,并在缀饰态表象中给出了定性解释。在双重电磁诱导透明现象中,透明窗的位置和吸收峰值可以通过调节外加相干场的失谐量来进行控制,而且透明点的位置可以连续变化。每个透明窗口在吸收最低时都伴随着高折射率,因此可以在此介质中实现超光速传播。 相似文献
11.
为了保证移动地面站光电跟瞄系统在野外复杂环境下具有稳定的跟踪精度,针对-20~40℃宽工作温度范围下信标接收镜头成像光斑弥散的问题,进行了光学系统与光机结构的设计,提出了一种以步进电机驱动补偿镜组的温度补偿方案。分析了极限温度条件下光学系统性能的改变以及不同温度补偿方案的效果,针对光电跟瞄系统的指标要求,设计了光机结构并进行了力学、光学性能的分析。分析结果表明,系统一阶模态为370 Hz;补偿镜组向前移动0.695 mm能够补偿-20℃时光学系统成像光斑的弥散,令中心视场光斑尺寸由73μm降为3.2μm,边缘视场光斑尺寸由77μm降为15.7μm;向后移动0.885 6 mm能够补偿40℃时成像光斑的弥散,令中心视场光斑尺寸由94μm降为3.9μm,边缘视场光斑尺寸由96μm降为21.8μm;使用ZYGO干涉仪对光学系统的像质进行检测,波像差RMS值(均方根值)为0.061λ(λ=632.8 nm),PV值(峰谷值)为0.466λ,能够满足跟瞄系统指标要求。 相似文献
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Sayed Ali Akbar Ghorashi 《Annalen der Physik》2020,532(2):1900336
It is shown that hybrid Dirac and Weyl semimetals can be realized in a 3D Luttinger semimetal with quadratic band touching (QBT). This is illustrated using a periodic kicking scheme. In particular, the focus is on a momentum-dependent driving (nonuniform driving) and the realization of various hybrid Dirac and Weyl semimetals is demonstrated. A unique hybrid dispersion Dirac semimetal with two nodes is identified, where one of the nodes is linear while the other is dispersed quadratically. Next, it is shown that by tilting QBT via periodic driving and in the presence of an external magnetic field, one can realize various single/double hybrid Weyl semimetals depending on the strength of external field. Finally, it is noted that in principle, phases that are found in this work can also be realized by employing the appropriate electronic interactions. 相似文献
14.
A steady analytical solution of an open four-level inversionless lasing system with a driving field having the phase fluctuation has been given, and the effects of the finite width due to the phase fluctuation on the gain, dispersion, and population difference have been analyzed by using the numerical simulation from the steady analytical solution. It is found that: with the linewidth increasing, the gain decreases and the absolute value of population difference between levels coupled by the probe field increases, but the variation of the linewidth cannot change the properties of the inversionless lasing and refractive index increase of the system; when the linewidth does not equal to zero, the system can still get a high refractive index with zero absorption, and these conclusions have very obvious difference from those obtained in other inversionless lasing systems. 相似文献
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Effects of relative phase on transient evolution in an open resonant ladder-type atomic system
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In an open ladder-type resonant atomic system, variation in relative
phase between probe and driving fields does not affect the transient
evolution of populations, but it has remarkable effects on gain and
dispersion of the probe field. No matter whether an incoherent pump
is present or absent, transient and stationary gains without
inversion (GWI) always can be obtained by choosing an appropriate
value of the relative phase. When the incoherent pump is absent,the
values of transient and stationary GWIs are much larger and the time
interval required to reach the stationary value is longer than those
when the incoherent pump is present. Varying the exit rate and the
ratio between injection rates can obviously change the
phase-dependent GWI. In addition, in the transient evolution
process, the phenomenon of high dispersion (refractive index)
without absorption occurs at some values of relative phase. In the
corresponding closed system, the stationary GWI can be obtained by
choosing an appropriate value of relative phase only when incoherent
pump exists, moreover the gain is smaller than that in the open
system. 相似文献
17.
X. J. Fan A. Y. Li S. F. Tian D. M. Tong S. Q. Gong Z. Z. Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):483-488
We studied effects of the relative phase between the probe and driving fields on the absorption and dispersion properties
in an open three-level ladder system with spontaneously generated coherence but without incoherent pumping. It is shown that
by the phase controlling, switching from absorption to lasing without inversion (LWI) and enhancing remarkablely LWI
gain can be realized; large index of refraction with zero absorption and the
electromagnetically induced transparency can be obtained. We also find that
varying the atomic injection and exit rates has a considerable influence on
the phase dependent-absorption property of the probe field, existent of the
atomic injection and exit rates gives the necessary condition of the
realization of LWI, getting LWI is impossible in the corresponding closed
system without incoherent pumping. 相似文献
18.
开放V型无反转激光系统相位涨落的影响 总被引:1,自引:1,他引:0
通过对从开放的V型双泵浦系统的定态解析解得到的数值计算结果的分析表明:1)驱动场相位将涨落导致一个有限线宽;一般说来,被探测场耦合的上下两能级间的粒子数差随线宽的增加而减小,当线宽增加到一定值时,系统将发生从传统的反转激光到无反转激光的转化;线宽的增加将使无反转激光增益降低;当线宽不为零时,仍可产生无吸收高色散(折射率)2)线宽变化对增益、色散和粒子数差影响的性质和大小与系统其它参量的取值密切相关,只有适当选择线宽和系统其它参量的值才能获得最大的无反转激光增益和无吸收高色散(折射率). 相似文献
19.
INFLUENCE OF DRIVING-FIELD PHASE FLUCTUATION ON ABSORPTION AND DISPERSION IN A SIMPLE THREE-LEVEL ATOMIC SYSTEM
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The steady-state behavior of a simple three-level atomic system has been investi-gated by taking into account the effect of phase fluctuations in the driving field. For a monochromatic driving field, lasing with or without inversion can be established over a wide frequency range for the probe and driving fields. A large refractive index can also be generated even if the population inversion is positive. For a finite linewidth of the driving field, the refractive index enhancement tends to decrease. Furthermore, a behavior change from inversion laser to noninversion laser can occur as the driving field linewidth increases. 相似文献
20.
High index of refraction via quantum interference in a three-level system of Er^3+-doped yttrium aluminium garnet crystal
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A simple three-level system is proposed to produce high index of refraction with zero absorption in an Er^3+-doped yttrium aluminium garnet (YAG) crystal, which is achieved for a probe field between the excited state 4I13/2 and ground state 4I15/2 by adjusting a strong coherent driving field between the upper excited state 4I11/2 and 4I15/2. It is found that the changes of the frequency of the coherent driving field and the concentration of Er^3+ ions in the YAG crystal can maximize the index of refraction accompanied by vanishing absorption. This result could be useful for the dispersion compensation in fibre communication, laser particle acceleration, high precision magnetometry and so on. 相似文献