Stochastic quasi-phase matching in nonlinear-optical crystals with an irregular domain structure

Abstract

We show the existence of a new class of astrophysical objects where the self-gravity of the dust is balanced by the force arising from shielded electric fields on the charged dust. The problem of equilibrium dust clouds is formulated in terms of an equation of hydrostatic force balance together with an equation of state. Because of the dust charge reduction at high dust density, the adiabatic index reduces from two to zero. This gives rise to a mass limit M AS for the maximum dust mass that can be supported against gravitational collapse by these fields. If the total mass M D of the dust in the interstellar cloud exceeds M AS , the dust collapses, while in the case M D < M AS , equilibrium may be achieved. The physics of the mass limit is similar to the Chandrasekhar's mass limit for compact objects, such as white dwarfs and neutron stars.

Nonlinear effects in random lasers

“…An important result of this section is that nonlinear wave-mixing effects seem to be promoted by the randomness of such systems. Similar conclusions for three-wave mixing in random nonlinear materials have been reported in the past [35,36] and more recently [37][38][39][40]. Such studies reported that phase-matching conditions, which can be difficult to achieve in pure and homogeneous materials, can be met more easily in a random structure although conditions are not optimized.…”

Parametric wave interaction in one-dimensional nonlinear photonic crystal with randomized distribution of second-order nonlinearity

“…Numerical simulations were also used by Vidal and Martorell [34] to study the diffusive character of the second harmonic generated in random 1D crystal. These simulations also confirmed the well known analytical results that the disorder-induced loss of phase correlation leads to the emitted signal growing linearly with propagation distance [35,36]. In their recent work Bravo-Abad et al suggested that light scattering by randomly distributed ferroelectric domains might contribute towards appearance of forward emission peak of the second harmonic signal [37].…”

Transverse second-harmonic generation from disordered nonlinear crystals

“…While, strictly speaking, the case considered here is two-dimensional, it turns out that even the simple 1D theory already provides a fairly good agreement with the experimental results. Following [12] and the discussions by Morozov and Chirkin [13] and Dolino [14] one can show that the intensity of the SH wave generated in a medium with random distribution of ferroelectric domains is given by…”