Tunable refraction and reflection of self-confined light beams

Abstract

Here we report the robust propagation, refraction and reflection of optical spatial solitons at the interface between two regions of a nematic liquid crystal. The ability to independently tune the optical properties of each region enables us to steer the beams by refraction and total internal reflection by as much as −18 and +22 degrees, respectively. Moreover, the extended (nonlocal) and anisotropic response of our system supports polarization healing of the solitons across the interface as well as non-specular filament reflection. Finally, exploiting the inherent and alloptically tunable birefringence, we demonstrate unprecedented nonlinear Goos-Hänchen lateral shifts in excess of 0.5 mm.

Liquid Crystal Light Valves: a versatile platform for Nematicons

“…The control of their trajectories is relevant in reconfigurable interconnects [1][2][3][4]. In nematic liquid crystals, recent progress on spatial solitons ("Nematicons") and their control include electro-optic and opto-optical deviation and interactions, with overall changes in angle as large as 40 degrees [4][5][6][7][8].…”

Topological Imbert-Fedorov Shift in Weyl Semimetals

“…Classically, the physics of a beam of light being reflected at an interface is governed by geometric optics law, where the photons are treated as classical particles. In contrast, when considering the wave nature of photons, spatial shifts at the interface appear as longitudinal shift in the incident plane [1][2][3] , or transverse shift normal to the incident plane [4][5][6][7][8][9] , which are known as the Goos-Hänchen (GH) effect and the ImbertFedorov (IF) effect, respectively. Due to all particles possessing the wave-particle duality, the spatial shifts are also expected for other particles.…”

Molding Optical Waveguides with Nematicons

“…In conclusion, we have demonstrated that judicious doping of nematic liquid crystals and interact to implement simple as well as complex circuits for signal interconnects and processing, including, e.g., bends, [13,15,22] junctions, [23] multiplexers. [14] …”

“…Hence, nematicon waveguides only exist as long as the defining beam propagates in the medium (or shortly thereafter until material relaxation has completed). They exhibit a fully flexible transverse (graded index) profile and longitudinal shape (trajectory), which can be modified through external stimuli such as electric fields, [13,15,21] as well as through the interaction with other beams, [22,23] offering a wide range of possibilities for realizing three-dimensional circuits and interconnects such as inplane and skew bends, spirals, junctions and splitters. [5] Hence, it would be extremely beneficial or even strategic to acquire the ability to "freeze" such real-time structures into permanent ones crafted in the medium.…”

“…[5,11] Nematicons can also confine and route co-polarized signals at shorter and longer wavelengths than the soliton itself; [5] hence, they entail an entire class of guided-wave circuits induced and controlled by propagating beams, including bistable elements [12] as well as all-optical routers and interconnects for optical processing. [13][14][15][16] Nonetheless, since they stem from beaminduced reorientation competing with the director distribution determined by the sample boundaries, nematicons are subject to restoring elastic forces as well as to temperature and torque fluctuations. [17] As a result, they exhibit trajectory fluctuations in the transverse direction, particularly when high optical powers are used to increase the index contrast or to maintain the confinement over extended propagation distances, the latter typically limited by scattering losses.…”