Exciton-polariton dynamics in a GaAs bulk microcavity

We present a full analysis of exciton dynamics in a GaAs λ/2 bulk microcavity following excitation by ultrafast laser pulses. Coherent dynamics was probed by means of an interferometric technique; beating and dephasing times were studied for various excitation intensities. At high incident power, population effects begin to show up reducing exciton oscillator strength and suppressing Rabi splitting. This feature produces marked non-linearities in the input-output characteristic of the optical functions, which were studied in view of reaching bistable operation. Theoretical calculations performed within the transfer-matrix framework show good agreement with experimental results.     

Measurement of the optical Stark effect in semiconducting carbon nanotubes

A strong optical Stark effect has been observed in (6,5) semiconducting single-walled carbon nanotubes by femtosecond pump-probe spectroscopy. The response is characterized by an instantaneous blueshift of the excitonic resonance upon application of pump radiation at photon energy well below the band gap. The large Stark effect is attributed to the enhanced Coulomb interactions present in these one-dimensional materials.     

The optical Stark effect in semiconductor quantum wires

A new approach for controlling the optical emission wavelength of semiconductor quantum wires is proposed. The wavelength control resides upon the effect of an intense, long-wavelength laser field radiation applied to the semiconductor structure. Under such condition a strong optical Stark effect leads to optical tunability. Calculation of the optical Stark effect was carried out in the frame of the nonperturbative theory and finite difference method. Different geometries concerning the size of GaAs–AlGaAs quantum wires as well as the polarization direction and the strength of the applied laser field with respect to the quantum structure were considered.     

Multiphoton transitions and the resonant optical Stark effect in AgBr nanocrystals

Nonlinear absorption of 30-ps light pulses with λ = 560 nm in AgBr nanocrystals is experimentally studied in the range of intensities 10⁸–10¹⁰ W/cm². The results of a theoretical analysis show that the absorption is related to direct interband n-photon transitions. With increasing light intensity j, the number n increases and the region of the k-space changes for the transitions predominantly contributing to the absorption. It is shown that, due to specific features of the AgBr electronic band structure, the probabilities of two-photon transitions for the light at λ = 560 nm are anomalously low, while those of four-photon transitions are anomalously high. In addition, the increase in the two-photon transition rate with increasing intensity is blocked at j ? 10⁸ W/cm² due to the resonant optical Stark effect and due to a gap arising in the band spectrum, rearranged because of the interaction with light.     

Vortices in the microcavity optical parametric oscillator

A theoretical treatment is presented for a novel from of optical vortex state, in a microcavity optical parametric oscillator (OPO). The state comprises a vortex/anti-vortex pair in the signal and idler beams, with a Gaussian pump. A numerical solution of the microcavity OPO equations shows that such a vortex can be stable.     

Dominant effect of polariton-polariton interactions on the coherence of the microcavity optical parametric oscillator

The importance of interaction effects in determining the temporal coherence of spectrally and spatially isolated single modes of the microcavity optical parametric oscillator (OPO) is demonstrated. As a function of macroscopic occupancy, the coherence time (tau c) first increases linearly and then exhibits saturation behavior, reaching maximum values of up to 500 ps. Good agreement is found with a model including fluctuations in polariton number and polariton-polariton interactions between the OPO states. tau c is a property of the coupled OPO system, a result confirmed by the finding of equal coherence times for signal and idler, even though the idler is subject to strong additional scattering.     

一种新型光学微腔的理论分析

应用波动光学理论,分析了一种新型锥顶柱状光学微腔的本征模式,得到了谐振腔的谐振波长表达式.在谐振波长1550 nm附近进行了设计与仿真优化,优化结果显示新型谐振腔与传统平行腔相比,在腔长为4512.5 nm,直径为3134.4 nm时,其品质因数可以提高22.4%,达到了49928.5,同时谐振腔的有效模式体积减小了47.8%.     

Spontaneous emission and energy transfer in the optical microcavity

Optical microcavities allow control over the interaction between light and matter, thus making them an important testing ground for basic optical physics. This review focuses on two of these interactions, spontaneous emission and energy transfer. Emphasis is placed on the underlying concepts, which are presented in the context of recent developments. Practical application of the microcavity concept to devices is now well underway and a discussion of these aspects forms an integral part of the review. This field is far from mature and though much has been accomplished, many questions in this area remain, some of which are identified and discussed.     

10.784μm无镜斯塔克效应光学双稳性

利用同位素C~(13)O_2~(16)激光器R(18)支线与NH_3分子(as)_Q(6,6)跃迁间的相互作用,观察到了斯塔克效应光学双稳性和光学限幅,分析了含有多普勒加宽的稳态理论,实验结果与理论分析结论一致.     

Field applied (FMD) computer simulation of the frequency doubled optical Stark effect

It is shown by field applied molecular dynamics computer simulation (FMD) of liquid water that the frequency doubled optical Stark effect is accompanied by novel second order rise transients which have no known counterpart in orientational theory, based on Langevin/Kielich functions. In the statistically stationary, post transient, steady state, correlation function have been computed which are intricately dependent on the frequency of the pump laser. These transients can be obtained experimentally by modifications of optical Stark effect apparatus for measurement on a femtosecond time scale.     

Study of the Stark effect in xenon

A gas-discharge source of light is proposed for investigation of the Stark effect by the method of canal rays in fields of up to 200 kV/cm intensity. Measurements of displacements of 12 spectral lines of xenon in the region of 4300–5000 Å (2p-1s and 3p-1s transitions) were conducted. For seven spectral lines the Stark shifts were measured for the first time. On the basis of the measured shifts the constants of the quadratic Stark effect were determined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 35–40, July, 1973.     

Bose condensation of exciton polaritons in an optical microcavity

Two methods are considered for producing traps for exciton polaritons in an optical microcavity with an embedded quantum well. The first method for controlling polaritons consists in producing a polariton trap governed by the longitudinal confinement of photons. Traps of this type can be created using an optical microcavity with a variable width. In traps of the second type, the exciton confinement is ensured by a weak potential that is applied to a quantum well with excitons or when this well is subjected to an inhomogeneous deformation. The behavior of a two-component Bose condensate of photons and excitons is analyzed theoretically. The Bose condensate is described by the coupled system of equations of the Gross-Pitaevskii type. The approximate wave functions and the spatial profiles of coupled photon and exciton condensates are obtained.     

Visualizing the whispering gallery modes in a cylindrical optical microcavity

Whispering gallery modes in cylindrical integrated optics microcavities have, for what is to our knowledge the first time, been mapped with a photon scanning tunneling microscope. Optical images were obtained with a spatial resolution of 50 nm. By combination of information on the spatial optical distributions with wavelength-dependent measurements, an unexpectedly rich variety of intracavity phenomena, such as polarization conversion and interference of copropagating and counterpropagating modes, could be directly observed. A quantitative comparison of the experimental data with computer simulations results in a comprehensive understanding of the various whispering gallery modes inside the microcavity.     

Coherent generation of acoustic phonons in an optical microcavity

Ultrafast coherent generation of acoustic phonons is studied in a semiconductor optical microcavity. The confinement of the light pulse amplifies both the generation and the detection of phonons. In addition, the standing wave character of the photon field modifies the generation and detection phonon bandwidth. Coherent generation experiments in an acoustic nanocavity embedded in an optical microcavity are reported as a function of laser energy and incidence angle to evidence the separate role of the optical and exciton resonances. Amplified signals and phonon spectra modified by the optical confinement are demonstrated.     

光学微腔中少光子数叠加态的耗散动力学

通过考察耗散光学腔中少光子数叠加态的Wigner函数随时间 的变化行为, 揭示其非经典特性的动力学演化. 结果表明, 初始时Wigner函数为负的少光子数叠加态, 在耗散过程中其负性逐渐减小 直至消失, 并最后达到一个稳定的正值. 但这并不意味着耗散量子态非经典特性的完全消失. 实际上, 作为非经典特性的另一个重要参量, 光子的二阶关联函数g⁽²⁾(0) (g⁽²⁾(0)<1意味着光子是非经典地反聚束) 是一个耗散动力学不变的物理量. 我们证明, 光子的二阶反关联函数g^(2A)(0)却是一个随着耗散而改变的物理参量, 从而可以用于描述光学微腔中光量子态的耗散动力学行为. 最后, 我们给出一个在实验上如何制备少光子数叠加态并对其Wigner函数进行探测的方案.