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1.
The effect of soliton-induced transparency (SOIT) that arises for a weak pulse that interacts with one of allowed transitions
of inhomogeneously broadened three-level atoms with the V configuration of the levels under the action of a self-induced transparency soliton that simultaneously interacts with the
adjacent transition is studied theoretically. The effect is explained by phasing of the ensemble of dipoles oscillating with
different frequencies in the soliton field. The weak pulse is locked by the soliton, so that both pulses propagate with the
same velocity independently of the ratio of the propagation constants. If the latter are equal, the weak pulse loses no energy;
when they are different, the rate of energy loss is considerably slower than it follows from Beer’s law. 相似文献
2.
We have pointed out that coherent Raman beats (CRB) in a three-level system with inhomogeneous broadening of optical transition do not suffer from power broadening and AC Stark shift due to the probe laser field if the sublevel coherence from which the CRB are stimulated is prepared over a sufficiently wide frequency range of the inhomogeneous broadening. 相似文献
3.
Anindita Bhattacharjee 《Journal of Molecular Spectroscopy》2005,232(2):264-278
We have studied the feasibility of amplification without population inversion (AWI) in LiH molecule for three-level ladder, V, and Λ schemes. We have shown the salient features of AWI in a molecular system in comparison to that in an atomic system, viz. the dependence of gain profile on the choice of different rotational and vibrational transitions. Under different three-level schemes, the effect of homogeneous and inhomogeneous broadening on the gain profile has been studied. We have also studied the dependence of gain on different external parameters. The temporal evolution of gain has been analyzed and it was found that AWI is achievable in both the transient and the steady state regime. For all the three-level schemes and in particular for the ladder scheme, amplification of the weak probe was obtained using a coupling laser of smaller frequency. 相似文献
4.
在一个具有超精细结构的四能级原子系统中,为了压抑暂态过程和稳态过程两种情况下的弱探测光束的吸收,我们提出和分析了一种有效的拉曼散射计划。对于暂态过程,借助一个漂亮的Mathematic程序进行数值计算,我们发现在探测跃迁线中心探测吸收的幅度与一般的基于电磁感应透明的三能级原子系统相比要小。对于稳态情况,结果表明探测吸收在线中心能够被彻底地消除,正像通常的三能级电磁感应透明方案。特别地,我们的结果表明在拉曼共振的条件下探测吸收能够被彻底地消除,也就是说,对于稳态过程我们仅仅要求双光子失谐量在超精细二能级频率间隙内是零。与标准的三能级电磁感应透明方案相比,我们的四能级拉曼计划的优点之一是在拉曼共振条件下我们能观察到透明窗口,不需要严格地单光子和双光子失谐量为零。因此,原子超精细结构对于获取电磁感应透明不是一个障碍。 相似文献
5.
Comparison between effects of Doppler broadening on pure and non-pure inversionless gains with frequency up-conversion
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A study is made of the effects of Doppler broadening on
pure gain without inversion, which means that neither one-photon
nor two-photon inversions are allowed, and non-pure gain without
inversion, which means that one-photon inversion does not occur
but two-photon inversion is present, in a closed Λ-type
three-level system with incoherent pumping. It is shown that when
the driving field is resonant but the probe field is not, in a
certain range of Doppler width, for the case of the lower degree of
frequency up-conversion, generally, pure gain without inversion
increases monotonically and non-pure gain without inversion does
not monotonically increase or decrease with increasing Doppler width;
for the case of the higher degree of frequency
up-conversion, pure gain without inversion decreases
monotonically but non-pure gain without inversion cannot be
produced. In the case of two-photon resonance, in some range of
Doppler width, pure gain without inversion does not
monotonically increase or decrease while non-pure gain without
inversion decreases monotonically with Doppler width increasing.
Finally, an experimental scheme for examining our theoretical result
is given. 相似文献
6.
This paper studies the propagation effect in a closed lambda-type three-level atomic system with Doppler broadening. It is shown that, Doppler broadening due to atomic motion and propagation effect associated with driving field depletion along the active medium decreases obviously the gain and output of the lasing without inversion (LWI); the relative phase between the probe and driving fields has a remarkable modulation role to the propagation effect on LWI when Doppler broadening presents; by choosing suitable value of the relative phase, we can get the largest gain and output of LWI. 相似文献
7.
8.
The coherent superposition of two-atomic levels induced by coherent population trapping is employed in the two-level system, the standard three-level Λ type scheme and the four-level N-type systems and a weak probe pulse scans across the system. A theoretical analysis about the response of medium to the probe field is given. It is shown that under different initial conditions, the coherent superposition of the dark state exhibits abundant optical phenomena response to the probe field. It can change the absorption or gain and the dispersion relationship in the medium experienced by the probe. In the embedded three-level scheme, the probe experiences a crossover from absorption to transparent and then to amplification. Consequently the group velocity of the probe pulse can be controlled to propagate either as a subluminal, a standard, a superluminal or even a negative speed. In the embedded four-level N-type system, it can give an enhancement to the Giant Kerr effect and overcome the limitation of two-photon absorption, then make the nonlinear properties of the medium richer than the traditional N-type scheme. 相似文献
9.
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11.
The experimental results are given on the broadening characteristics of the time and frequency profile of the femtosecond pulse passed through a SNOM fiber probe. The power threshold for the spectral and temporal broadening was 158 μw for pulses with 250 fs width and the repetition rate of 250 kHz at 830 nm wavelength. The time broadening reached lps for 250 fs incident pulse of 500 μw. A finite-difference time-domain (FDTD) simulation was carried out to illuminate the transmission properties of ultrafast pulse through the SNOM probe. The broadening influence on temporal resolution spectrum and near-field fluorescence excited by two-photon technique are discussed. 相似文献
12.
Niloy Dutta 《Optical and Quantum Electronics》1979,11(1):1-9
The quantum mechanical Langevin equations of a cavity where laser action takes place both by ordinary population inversion and stimulated Raman scattering is discussed for both single mode and multimode oscillation of the pump and Raman laser. Expressions for amplitude correlation and linewidth due to phase diffusion are obtained both for homogeneous and inhomogeneous broadening. 相似文献
13.
1 Introduction Theultrafastpulsescanningnear fieldopticalmicroscopyandtemporalresolutionnear fieldspectraltechnique,whichdevelopedfromthecombinationofscanningnear fieldopticalmicroscopy (SNOM )andtheultrafastpulse,haveattractedgreatinterest[1~ 3] .Thesetech… 相似文献
14.
We propose a photon echo quantum memory scheme using detuned Raman coupling to long-lived ground states. In contrast to previous three-level schemes based on controlled reversible inhomogeneous broadening that use sequences of pi pulses, the scheme does not require accurate control of the coupling dynamics to the ground states. We present a proof-of-principle experimental realization of our proposal using rubidium atoms in a warm vapor cell. The Raman resonance line is broadened using a magnetic field that varies linearly along the direction of light propagation. Inverting the magnetic field gradient rephases the atomic dipoles and re-emits the light pulse in the forward direction. 相似文献
15.
YANG Xihua SUN Zhenrong LI Hua DING Liang’en WANG Zugeng 《Chinese Journal of Lasers》2001,10(2):123-126
1 Introduction Electromagneticallyinducedtransparency(EIT)hasattractedmuchattentionduetoitsextensiveapplications,suchasquantumnoisereduction[1] ,pulsematching[2 ,3] ,andenhancementofnonlinearmixing[4 ,5] .Inessence,EITisanatomiccoherenceinducedbyastrongcouplingl… 相似文献
16.
The transient properties of electromagnetically induced transparency (EIT) are studied with different probe pulse energies for the first time in the 3S-3P3/2-4D ladder-type three-level system of sodium atom. The EIT effect would be reduced with the increase of the probe pulse energy.Theoretical calculation is carried out by solving the time-dependent matrix equation. The experimental results agree well with the theoretical calculation. 相似文献
17.
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
18.
M. H. Hovhannisyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2014,49(3):103-109
Abilities of the method of accumulation of coherent unstable response of a medium for amplification of the rotated component of the probe wave’s polarization in the atomic medium of three-level atoms are studied. Probe wave is examined in frames of the perturbation theory and its frequency is considered near to one photon resonance from the ground to the first excited level. The intense monochromatic pump field connects two excited energy levels and propagates through the medium without a change. The broadening of spectral lines caused by the relaxation processes and the Doppler broadening are included into the calculations. It is shown that by multiple consistent instantaneous change of input probe field’s phase from 0 to π and back, it is possible to obtain, in the tail part of the rotated component of the probe field, a separate narrowed light pulse along with the increase in intensity by more than an order of magnitude with respect to the input field. 相似文献
19.
An electromagnetically induced absorption grating is formed in a three-level atomic vapor under the condition of electromagnetically induced transparency in which the strong coupling beam is replaced by a standing wave. The transmission and reflection behaviors of the weak probe beam are greatly modified at certain frequencies near the two-photon resonance. An all-optical two-port signal router-all-optical switch is demonstrated. 相似文献
20.
Eiichi Hanamura 《Optics Communications》1973,9(4):396-399
We show theoretically that the effect of self-induced transparency can be supported by the two-photon transition in the system of three-level atoms. The distortionless propagation of the radiation wave is composed of a train of pulses which is described by a trigonometric function, and in one limit, it approaches to a single pulse with lorentzian form for the radiation intensity. 相似文献