In this paper we present a numerical study on the optimization of dispersion of a photonic crystal fiber infiltrated with water-ethanol mixtures. The advantage of such an approach stems from the fact that the dependence of the refractive index on temperature is larger in liquids than in solid materials. Here, we examine photonic crystal fibers with a regular, hexagonal lattice and with various geometrical and material parameters, such as different number of rings of holes, various lattice constants and the size of core and air-holes. Additionally, for the optimized structure with flat dispersion characteristics, we analyze the influence of temperature and concentration of the ethanol solution on the dispersion characteristic and the zero dispersion wavelength shift of the fundamental mode.
We present a numerical study of the dispersion characteristic modification in a nonlinear photonic crystal fibre (PCF) infiltrated with organic solvents. The PCF is made of PBG08 glass and was developed in the stack-and-draw process. The PBG08 glass has a high refractive index (<i>n</i> < 2.0), high nonlinear refractive index (n<sub>2</sub> = 4.3×10<sup>−19 </sup>m<sup>2</sup>/W) and good rheological properties that allow for thermal processing of the glass without crystallization. In the numerical study 18 different solvents were used. The dispersion, mode area, and losses characteristics were calculated. The zero dispersion wavelength (ZDW) of the fibre can be shifted towards longer wavelengths by approx. 150 nm by using Nitrobenzene as infiltrating liquid and by a smaller value using other liquids. At the same time the mode area of the fundamental mode increases by approx. 5 to 15% depending on the wavelength considered. The confinement losses increase significantly for six analysed liquids by a few orders of magnitude up to 10<sup>2</sup> dB/m. Our approach allows to combine high nonlinearities of the soft glass with the possibility to tune zero dispersion wavelength to the desired value.
We present a two-dimensional cellular automata (CA) model involving a set of two-level subsystems (”atoms”)
which are located in square lattice, and can emit and absorb quanta of energy. Our model is an extension
of the one-dimensional model discussed in the papers.1, 2 We concentrate on the spreading of disorder in the
system and propose entropic parameters describing two-dimensional system’s dynamics. We show that whereas
entropic measure undergoes saturation effects, its counterpart normalized per number of excitations can exhibit
We have simulated spectra of weak probe absorption from one of two hyperfine structure (hfs) components of an atomic ground state, to a hfs manifold of an upper state. A stronger coupling transition was assumed to bind the other hfs component of the ground state with the same upper hfs manifold. The purpose of this simulation was to study the impact on the spectral features in probe absorption from the presence of a state to which the electric-dipole transition is allowed for coupling, but forbidden for probing. In relation to our other (experimental) work, we considered the D2-line transitions for <sup>85</sup>Rb. With coupling from the 5S<sub>1/2</sub>(<i>F</i>=2) state, as in our experiment, the 5P<sub>3/2</sub>(<i>F'</i>=1) state is coupled but not-probed from the 5S<sub>1/2</sub>(<i>F</i>=3) state. In calculations we searched for steady-state solutions of optical Bloch equations assuming a 5-level model and RWA. The collisionless (cold) atoms were considered, and we assumed that decoherence was entirely due to natural decay and exciting lasers' linewidths. We investigated probe absorption spectra as a function of both coupling-field-induced Rabi frequency Ω<sub>c</sub>, and coupling field detuning from the atomic resonances. The 5-level model spectra were compared with the corresponding spectra result of 4-level model calculations performed by omission of the 5P<sub>3/2</sub>(<i>F'</i>=1) level. Even for small Ω<sub>c</sub> values close to the natural linewidth, for some detunings a considerable influence of the 5P<sub>3/2</sub>(<i>F'</i>=1) state on the spectra was observed which cannot be ignored in interpretations.
We discuss the simulation method allowing modeling of quantum unitary dynamics for quantum nonlinear scissors systems. In particular, we consider the model of two nonlinear oscillators (Ker-like coupler) excited by an external field. We show that the time-evolution of the system is closed within a finite set of <i>n</i>-photo states and the Bell-like states are generated. Thus, we prove that the numerical method applied can be used as tools of quantum-mechanical simulations leading to the interesting results.
In this paper we consider a generalized double dispersion equation of Porubov’s type<sup>4,5</sup>. which describes the propagation of the longitudinal strain waves in the rod. By analogy with the optical case<sup>2</sup>, the higher orders of nonlinearity have been included which leads to an interesting class of traveling solitary waves for both cases: without cubic nonlinearity and with its presence. The F-expansion method described in3 has been used. As a byproduct, we obtain the results given previously by other authors<sup>4,5</sup>. It will be shown that our analytical solutions describe very well the results obtained by numerical simulations<sup>6</sup>.