Efficient Third-Harmonic Generation by Inhomogeneous Quasi-Phase-Matching in Quadratic Crystals

Abstract

We investigate the generation of optical third-harmonic frequency in quadratic crystals with a nonlinear domain lattice optimized with the aid of a random number generator. In the developed Monte Carlo algorithm and numerical experiments, we consider domain thicknesses to be taking either the values d1 or d2, with d1 and d2 being the coherence lengths for the cascaded parametric interactions 2ω =ω + ω and 3ω = 2ω + ω, respectively. We focus on the cases with single segments formed by equal and/or different domains, showing that frequency tripling can be achieved with high conversion efficiency from an arbitrary input wavelength. The presented approach allows one to accurately determine the optimized random alternation of domain thicknesses d1 and d2 along the propagation length.

The Propagation Dynamics of the Symmetric Pearcey Gaussian Beam in the Kerr Medium

“…In the paraxial optical system, the propagation of the SPGBs with astigmatism in parabolic potential satisfies the dimensionless Schrödinger equation [ 41,42 ] $$$$\begin{eqnarray} 2 i\frac{\partial \Psi }{\partial Z}+\frac{\partial ^{2} \Psi }{\partial X^{2}}+\frac{\partial ^{2} \Psi }{\partial Y^{2}}+\frac{2 n_{2}}{n_{0} \sigma ^{2}}|u|^{2} u=0 \end{eqnarray}$$$$where, $$X=\frac{x}{w_0}$$, $$Y=\frac{y}{w_0}$$ are a normalized horizontal coordinates, $$Z=\frac{z}{2Z_R}$$ ($$Z_R=\frac{kw_0^2}{2}$$) is normalized longitudinal transmission distance, $$\Psi (x,y,z)$$ is the amplitude of SPGBs, $$w_0$$ indicates the initial beam width of the Gaussian beam, $$k=2\pi$$/$$\lambda _0(\lambda _0$$ represents the wavelength in the Kerr medium) is the linear wave number, …”

Transmission of Vortex Solitons in Three-Dimensional χ(2) Helical-Periodically Poled Ferroelectric Crystals

“…The radiationinduced optical absorption and phase-mismatch for third-order QPM second harmonic generation (SHG) in congruent LiNbO 3 crystals were subsequently investigated [16]. Highefficiency third-harmonic generation is achieved by designing an inhomogeneous QPM structure in a quadratic crystal using a Monte Carlo algorithm [17]. Multiplexing linear and nonlinear Bragg diffractions through volume gratings fabricated by femtosecond laser writing in lithium niobate crystals was reported recently [18].…”