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,…     

Influence of atomic densities on propagation property for ultrashort pulses in a two-level medium

The influence of atomic densities on the propagation property for ultrashort pulses in a two-level atom (TLA) medium is investigated. With higher atomic densities, the self-induced transparency (SIT) cannot be recovered even for 2πultrashort pulses. New features such as pulse splitting, red-shift and blue-shift of the corresponding spectra arise, and the component of central frequency gradually disappears.     

相干驱动场的线宽对电磁感应透明的影响

考虑相干驱动场的线宽，探讨了其对双激发态原子三能级系统中的电磁感应透明现象的影响，得到结论：相干驱动场的线宽抑制了介质对弱探测光的透明。     

INFLUENCE OF DRIVING-FIELD PHASE FLUCTUATION ON ABSORPTION AND DISPERSION IN A SIMPLE THREE-LEVEL ATOMIC SYSTEM

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.     

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.