Observation of Optical Spatial Solitons in a Highly Nonlocal Medium

Abstract

We report on the observation and quantitative assessment of self-trapped pulsating beams in a highly non-local nonlinear regime. The experiments were conducted in nematic liquid crystals and allow a meaningful comparison with the prediction of a scalar theory in the perturbative limit, while addressing the need for beyond-paraxial analytical treatments.

Matter-wave solitons supported by field-induced dipole-dipole repulsion with spatially modulated strength

“…This means that, for the narrow solitons, scaling relations are obtained in the form of Eqs. (25) and (27), but with 2α replaced by α. In particular, for α = 4 Eq.…”

“…The DDIs account for a number of remarkable phenomena in ultracold Bose gases [9]- [11], such as various pattern-formation scenarios [12][13][14][15][16], fractional domain walls [17], d -wave collapse [18,19], specific possibilities for precision measurements [20][21][22], stabilization of the dipolar BEC by optical lattices [23,24], the Einstein -de Haas effect [25], etc. Dipolar BECs can be also used as matter-wave simulators [26], to emulate, in particular, the creation of multi-dimensional solitons via the nonlocal nonlinearity-a subject which has also drawn much attention in optics, where nonlocal interactions of other types (with different interaction kernels) occur too [27][28][29]. In fact, the dipolar condensates not only emulate the situation known in optics, but also make it possible to predict the existence of solitons with novel properties.…”

Two-dimensional bright solitons in dipolar Bose-Einstein condensates with tilted dipoles

“…Two-dimensional (2D) optical bright solitons [13] and three-dimensional (3D) light bullets [14] have been reported in non-local media. In addition, nonlocal interactions significantly influence inter-soliton collisions [4,7,15,16] and may lead to the formation of soliton complexes [17,18].…”

Tunable refraction and reflection of self-confined light beams

“…The manner in which molecules reorient and arrange themselves in a nematic liquid crystal (NLC) gives rise to both a strong electro-optic response and a giant non-resonant optical nonlinearity 16,17 . The latter of these properties, in conjunction with the non-local nature of molecular ordering in NLCs, enables them to support stable, low-power two-dimensional solitons [18][19][20][21] , whereas the former allows distinct regions of a liquid crystalline structure to be independently tuned by the application of different voltages. This entails the definition of voltage-adjustable transitions between birefringent uniaxial media differing in refractive index, orientation and nonlinear response, which in turn offers a great deal of versatility in the study of light propagation and localization phenomena at and across interfaces.…”

“…An incident extraordinarily polarized optical beam, with electric field nonorthogonal to n, can interact with the induced dipoles and force the molecular reorientation. Such reorientational response enabled us to observe anisotropic spatial solitons in planar cells, the so-called nematicons 18 , as well as their interaction, periodic breathing, transverse dynamics and walk-off [20][21][22] . As reorientation can also be driven by a low-frequency electric field, for example, through a voltage applied across the thickness of the NLC cell 16,17 , linear, nonlinear and nonlocal properties of the medium can be externally adjusted 23 .…”