Discrete diffraction in two-dimensional arrays of coupled waveguides in silica

Abstract

The propagation of light in 5 x 5 and 7 x 7 cubic lattices of evanescently coupled waveguides is investigated for the first time, to the authors' knowledge. The results reveal ideal discrete diffraction and demonstrate the excellent quality of the waveguide arrays, which were manufactured in fused silica by femtosecond-laser-induced refractive-index modifications.

Discrete surface solitons in two-dimensional anisotropic photonic lattices

“…That can be understood as the localization of a discrete optical soliton near the surface [4] for powers exceeding a certain threshold value, for which the repulsive effect of the surface is balanced. A similar effect of light localization near the edge of the waveguide array and the formation of surface gap solitons have been predicted and observed for defocusing nonlinear media [5,6].It is important to analyze how the properties of nonlinear surface waves are modified by the lattice dimensionality, and the first studies of different types of discrete surface solitons in two-dimensional lattices [7,8,9,10] revealed, in particular, that the presence of a surface increases the stability region for two-dimensional (2D) discrete solitons [10] and the threshold power for the edge surface state is slightly higher than that for the corner soliton [9].In this Letter we consider anisotropic semi-infinite twodimensional photonic lattices and study the crossover between one-and two-dimensional surface solitons emphasizing the crucial effect of the lattice dimensionality on the formation of surface solitons.We consider a semi-infinite 2D lattice [shown schematically in Fig.2(a) below], described by the system of coupled-mode equations for the normalized amplitudes u n,m [11,12],where ξ is the normalized propagation distance. We de- fine the lattice coupling as follows:…”

Tunability of discrete diffraction in photonic liquid crystal fibres

“…It can be shown that in such photonic struc− tures, output intensity profile strongly depends on optical and geometrical parameters of the system (including wave− length, beam−size, lattice arrangement and index contrast). Discrete photonic systems (of different dimensionality) have been practically achieved in various materials, includ− ing (fused) silica [19][20][21], semiconductors [22][23], photo− refractives [24][25], polymers [26], ferroelectrics [27], and liquid crystals [12,28], thus giving a rise to many new phe− nomena which are not accessible in homogeneous bulk media. An overview of theoretical and experimental devel− opments in the area of discrete light propagation in linear and nonlinear photonics lattices can be found in Refs.…”

“…This has resulted in intensified interest in the higher−dimensional photonic lattices whose geometry in combination with non− linear dynamics gives rise to all−optical switching and rout− ing (e.g., based on two−dimensional solitons) [31][32]. To date, two−dimensional (2D) waveguide lattices have been demonstrated in photorefractive materials [24][25], cubic [20] and hexagonal [19] waveguide arrays written with fs−laser pulses in fused silica, as well as in multi−core optical fibres [33]. Most of these solutions require specialized fabri− cation techniques, high energy densities (e.g., when nonlin− ear processes are applied to lattice fabrication) or do not offer dynamic tunability.…”

Light induced angular steering via Floquet-Bloch band-tunnelling in one-dimensional liquid crystalline photonic lattices

“…Unique properties of the system, arising from the lack of its rotational symmetry, offer the possibility of applications in all-optical switching [3][4][5] and readdressing [5][6]. In various nonlinear materials, the variety of discrete optical phenomena observed to the date in waveguide arrays includes discrete solitons [2,[7][8][9][10], gap solitons [11], discrete breathers [12], multiband solitons and their interactions [13], discrete blockers and routers [3,4]. Moreover, the specific geometry of the system allows for the investigations of phenomena typical for multi-level quantum-mechanical-like systems, including linear and nonlinear Bloch oscillations [14][15][16][17], as well as the dynamics of accelerated lattices, among which Landau-Zener tunnelling is an important aspect [18][19][20][21].…”