Solving the Kohn-Sham eigenvalue problem constitutes the most computationally expensive part in self-consistent density functional theory (DFT) calculations. In a previous paper, we have proposed a nonlinear Chebyshev-filtered subspace iteration method, which avoids computing explicit eigenvectors except at the first self-consistent-field (SCF) iteration. The method may be viewed as an approach...

We study a coupled cavity laser configuration where a passively Q-switched Nd:YAG microchip laser is combined with an extended cavity, including a doped multimode fiber. For appropriate coupling levels with the extended cavity, we observed that beam self-cleaning was induced in the multimode fiber thanks to nonlinear modal coupling, leading to a quasi-single mode laser output. In the regime of ...

We find self-accelerating beams in highly nonlocal nonlinear optical media, and show that their propagation dynamics is strongly affected by boundary conditions. Specifically for the thermal optical nonlinearity, the boundary conditions have a strong impact on the beam trajectory: they can increase the acceleration during propagation, or even cause beam bending in a direction opposite to the in...

Self-focusing of intense laser beams and pulses of light in real nonlinear media is in general accompanied by material losses that require corrections to the conservative Nonlinear Schrödinger equations describing their propagation. Here we examine loss mechanisms that exist even in lossless media and are caused by shedding of energy away from the self-trapping beam making it to relax to an exa...

Analytical predictions of the triangle and clover heteroclinic bifurcations in the problem of self-oscillations stability loss near the 1:3 resonance are provided using the method of nonlinear time transformation. The analysis was carried out considering the slow flow of a self-excited nonlinear Mathieu oscillator corresponding to the normal form near this 1:3 strong resonance. Using the Hamilt...

It is shown that the magnitude of nonlinear nonreciprocity, self-induced by counterpropagating laser beams, is related to the anisotropic properties of the nonlinear third-order susceptibility (resulting in the light-induced birefringence and gyrotropy) and therefore is sensitive to the mutual arrangement of polarization of both of the beams. The invariants of nonlinear wave equations suggest a...

High-quality continuous (GO) thin films are prepared by a self-assembly method. Z-scan measurements during the laser-induced reduction process unveil in situ nonlinear responses in the GO film. Third-order nonlinear responses of the GO film can be tuned dynamically by varying the laser input fluence. GO thin films with tunable nonlinear responses and versatile patterning opportunities by using ...

In this paper we study the use of pseudorandom test techniques for linear and nonlinear devices, in particular Micro Electro Mechanical Systems (MEMS). These test techniques lead to practical BuiltIn-Self-Test techniques (BIST). We will first present the pseudorandom test technique for Linear Time Invariant (LTI) systems. Next, we will illustrate and evaluate the application of these techniques...

We suggest and demonstrate a novel platform for the study of tunable nonlinear light propagation in two-dimensional discrete systems, based on photonic crystal fibers filled with high index nonlinear liquids. Using the infiltrated cladding region of a photonic crystal fiber as a nonlinear waveguide array, we experimentally demonstrate highly tunable beam diffraction and thermal self-defocusing,...

in this paper an optimal controller is proposed for a self-balancing electrical vehicle called segway pt. this vehicle has one platform and two wheels on the sides and the rider stands on the platform. a handlebar, as a navigator, is attached to the body of segway, with which the rider controls the vehicle. since segway uses electrical energy produced by batteries, resource consumption manageme...