Reversality of optical interactions in noncentrosymmetric media

The interaction of an electromagnetic wave with a noncentrosymmetric crystal is not necessarily time reversible, and the departure from reversality may be seen in nonlocal (wave-vector linear) phenomena. However, relativistic symmetry with respect to simultaneous time and space inversion is always preserved in optics

Revealing the nanoparticles aspect ratio in the glass-metal nanocomposites irradiated with femtosecond laser

We studied a femtosecond laser shaping of silver nanoparticles embedded in soda-lime glass. Comparing experimental absorption spectra with the modeling based on Maxwell Garnett approximation modified for spheroidal inclusions, we obtained the mean aspect ratio of the re-shaped silver nanoparticles as a function of the laser fluence. We demonstrated that under our experimental conditions the spherical shape of silver nanoparticles changed to a prolate spheroid with the aspect ratio as high as 3.5 at the laser fluence of 0.6J/cm2. The developed approach can be employed to control the anisotropy of the glass-metal composites

Cubic optical nonlinearity of free electrons in bulk gold

A fast (τresponse &lt;90 fs) free-electron spin-flipping frequency-degenerate nonlinearity with a significant value of |χ(3)xxyy(ω,ω,ω,-ω) χ(3)xyyx(ω,ω,ω,-ω)| ~ 10-8 esu has been observed in bulk gold at 1260 nm by use of a new pump-probe polarization-sensitive technique. <br/

Dimensionality dependence of optical nonlinearity and relaxation dynamics in cuprates

Femtosecond pump-probe measurements find pronounced dimensionality dependence of the optical nonlinearity in cuprates. Although the coherent two-photon absorption (TPA) and linear absorption bands nearly overlap in both quasi-one and two-dimensional (1D and 2D) cuprates, the TPA coefficient is one order of magnitude smaller in 2D than in 1D. Furthermore, picosecond recovery of optical transparency is observed in 1D cuprates, while the recovery in 2D involves relaxation channels with a time scales of tens of picoseconds. The experimental results are interpreted within the two-band extended Hubbard model.Comment: 10 pages, 4 figure

Signatures of the excitonic memory effects in four-wave mixing processes in cavity polaritons

We report the signatures of the exciton correlation effects with finite memory time in frequency domain degenerate four-wave mixing (DFWM) in semiconductor microcavity. By utilizing the polarization selection rules, we discriminate instantaneous, mean field interactions between excitons with the same spins, long-living correlation due to the formation of biexciton state by excitons with opposite spins, and short-memory correlation effects in the continuum of unbound two-exciton states. The DFWM spectra give us the relative contributions of these effects and the upper limit for the time of the exciton-exciton correlation in the unbound two-exciton continuum. The obtained results reveal the basis of the cavity polariton scattering model for the DFWM processes in high-Q GaAs microcavity.Comment: 11 pages, 1 figur

Flexible transparent graphene/polymer multilayers for efficient electromagnetic field absorption

Thanks to its high electrical conductivity, a graphene plane presents a good shielding efficiency against GHz electromagnetic radiations. Several graphene planes separated by thin polymer spacers add their conductivities arithmetically, because each of them conserves the intrinsic properties of isolated graphene. Maximum absorption of radiations for frequency around 30 GHz is achieved with six separated graphene planes, which is the optimum number. This remarkable result is demonstrated experimentally from electromagnetic measurements performed in the K(a) band on a series of multilayers obtained by piling 1, 2, 3 … graphene/PMMA units on a silica substrate. Theoretical calculations convincingly explain the observed absorption and transmission data in the GHz domain. It is concluded that graphene/PMMA multilayers can be used as an efficient optically transparent and flexible shielding media

Polarization of light in nonlinear optics

Polarization of Light in Nonlinear Optics provides a unique and detailed introduction to polarization (vectorial) properties of light in intense light fields. The study and understanding of this subject is becoming increasingly important in laser physics, optoelectronics, spectroscopy and optical telecommunications. This volume gives a systematic introduction into the phenomenological and microscopic formalisms of the polarization phenomena in nonlinear optics. Crucial experiments on transmissive, reflective and pump-probe effects involving changing polarization state of light are also discussed. Polarization of Light in Nonlinear Optics will be extremely useful both as a detailed introduction to the subject for students of optical physics and nonlinear optics, and as a reference source for researchers in the fiel

The laser assisted field electron emission from carbon nanostructure

We present experimental and theoretical study of the femtosecond light-assisted field electron emission from nanocarbon films. We demonstrate that irradiation with intense femtosecond laser pulse allows one to achieve electron emission density of up to 13 nC/cm2 at a moderate applied static electric filed. The developed model well describes obtained experimental results and allows us to visualize physical mechanisms including heating of electron gas, multiphoton photoionization, and the space charge formation, which are responsible for the observed phenomena