Extraordinary optical transmission through metal gratings with single and double grooved surfaces

We investigate the transmission properties of a normally incident TM plane wave through metal films with periodic parabolic-shaped grooves on single and double surfaces using the finite-difference-time-domain method. Nearly zero transmission efficiency is found at wavelengths corresponding to surface plasmon excitation on a flat surface in the case where the single surface is grooved. Meanwhile, resonant excitation of surface plasmon polariton (SPP) Bloch modes leads to a strong transmission peak at slightly larger wavelengths. When the grating is grooved on double surfaces, the transmission enhancement can be dramatically improved due to the resonant tunnelling between SPP Bloch modes.     

Accurate determination of the absolute phase and temporal-pulse phase of few-cycle laser pulses

A Fourier analysis method is used to accurately determine not only the absolute phase but also the temporal-pulse phase of an isolated few-cycle (chirped) laser pulse. This method is independent of the pulse shape and can fully characterize the light wave even though only a few samples per optical cycle are available. It paves the way for investigating the absolute phase-dependent extreme nonlinear optics, and the evolutions of the absolute phase and the temporal-pulse phase of few-cycle laser pulses.     

Coherent population transfer with Coherent population transfer with chirped few-cycle laser pulses in an excited-doublet four-level system

The efficient excitation to particular states has attracted much attention in both physics and chemistry[1-10]. The stimulated Raman adiabatic passage technique for pop- ulation transfer has been implemented with continuous or narrow band laser pulse (nanosecond time scale)[1], but the requirement for large pulse areas seems to advise against the use of short pulse lasers. However, the use of ultrashort laser pulse may have some distinct advan- tages, such as producing high energy frequencies,…     

Zero-dispersion waveguide of sub-skin-depth terahertz plasmons using metallic nanowires

Global change in the dispersive behavior of terahertz （THz） plasmons on metal wires with wide radii ranging from 5 nm to 0.5 mm is systematically investigated. Through rigorous numerical calculations, we find that the dispersion of a metal wire with a radius of 5 nm increases by about 4-6 orders of magnitude compared with the case of a metallic wire with a radius of 0.5 mm. Zero-dispersion points appear when the frequency is lower than 3 THz, and the positions of the zero-dispersion points can shift with the frequency. Finally, we provide an explicit expression that agrees verv well with the numerical calculations.     

Optical bistability and multistability via multi-Raman-channel interference

We investigate the optical bistability and multistability behaviors in a closed three-level A-type atomic system. By adding a sideband on either hand of the transitions which are originally coupled by a coherent control field and a coherent probe field to disturb the two-photon resonance, bistability occurs due to two-channel interference. Increasing the sideband Rabi frequency leads to the switching from bistability to tristability. When the sideband simultaneously couples with both hands, we can easily obtain quadrastability.     

Entanglement dynamics of two qubits coupled by Heisenberg XY interaction under a nonuniform magnetic field in a spin bath

This paper investigates the entanglement dynamics of a Heisenberg XY model for a two-spin system in the presence of a nonuniform magnetic field.The master equations and the concurrence evolution equations for the initial α state are derived and analysed.It is shown that for the symmetric initial α state,only the nonuniform field can play a role in entanglement dynamics while the uniform field and the bath will not play such a role.For the asymmetric α state,the nonuniform field leads to the beat pattern oscillation of the concurrence evolution.The inhomogeneity of the field can enhance the entanglement by suppressing the decoherence effects of both the spin-orbit interaction and the spin bath.     

原子类原子系统光学特性的量子相干调控应用基础研究

简要介绍了在原子类原子小量子系统光学特性的量子相干调控应用基础研究方面所取得的一些成果,主要包括周期调制场控制弱光孤子传输、光学腔超窄线宽输出、非对称双量子阱中光学前驱波的分离以及极性分子系统中的电磁诱导透明现象等.     

Cavity linewidth narrowing with dark-state polaritons

We present a quantum-theoretical treatment of cavity linewidth narrowing with intracavity electromagnetically induced transparency(EIT). By means of intracavity EIT, the photons in the cavity are in the form of cavity polaritons:bright-state polariton and dark-state polariton. Strong coupling of the bright-state polariton to the excited state induces an effect known as vacuum Rabi splitting, whereas the dark-state polariton decoupled from the excited state induces a narrow cavity transmission window. Our analysis would provide a quantum theory of linewidth narrowing with a quantum field pulse.     

Electromagnetically induced transparency and controllable group velocity in a five-level atomic system

The optical properties of a five-level atomic system composed of a A-type four-level atomic and a tripod four-level atomic systems are investigated. It is found that the behaviors of electromagnetically induced transparency (EIT) and group velocity can be controlled by choosing appropriate parameters with the interacting dark resonances. In particular, when all the fields are on resonance, the slow light at the symmetric transparency windows with a much broader EIT width is obtained by tuning the intensity of the coupling field in comparison with its sub-system, which provides potential applications in quantum storage and retrieval of light.     

空间非傍轴激光束在非线性克尔介质中的相互作用

对于非线性克尔介质中的非傍轴双脉冲激光束的传输,通过数值求解修正的非线性Schroödinger方程发现:当入射光强度在一定的能量阈值以上,入射光束的间隔达到一定值时,空间双脉冲激光束在传输过程中会发生相互作用.这种相互作用不同于一般傍轴激光束之间的相互作用,它的作用效果以一束很小的分束光的形式表现出来.文中对这种相互作用的效果进行了报道,并对此做出了理论的解释.