Steering and switching of soliton-like beams via interaction in a nanocolloid with positive polarizability

Abstract

We unveil different regimes for the interaction between two orthogonally polarized soliton-like beams in a colloidal suspension of nanoparticles with positive polarizability. The interaction is always attractive. However, it noticeably changes as a function of the angle and the power distribution between the input beams. For small angles, both interacting solitons fuse into a single entity, whose propagation direction can be continuously steered. As the interaction angle increases, the resulting self-collimated beam can be practically switched between two positions when the power imbalance between the beams is changed. For interaction angles larger than ∼10°, the result is no longer a single emerging soliton when the input power is balanced between the two beams.

Self-confined light waves in nematic liquid crystals

“…Nevertheless, thermal heating can be important for two reasons, (i) the refractive index eigenvalues n ⊥ and n and the walk-off δ are temperature dependent [22,23,24,215,216] and (ii) the nematic metaphase exists in a restricted temperature interval [14]. NLC thermal absorption can be enhanced or tailored at specific wavelengths or spectral ranges by the addition of absorbing dyes [25] or nano-particles [26] to increase energy withdrawal from the light beam. Since the intensity of the beam is |A| 2 , the temperature is governed by the steady, forced heat equation…”

“…Thermo-optic nonlinear changes in NLC can be self-defocusing, while optical reorientation is self-focusing, so that thermal and reorientational effects in response to specific light polarizations can act in opposition. Standard undoped NLC, such as 5CB and E7, are nearly pure dielectric and the thermal contributions are weak; nevertheless these can be enhanced through the addition of dyes [25] or nano-particles [26]. These thermo-optic effects on nematicon behaviour and propagation are addressed in Section 7.…”

Light Confinement with Structured Beams in Gold Nanoparticle Suspensions

“…It should be stressed that optical trapping forces, playing an important role in the nonlinear properties of other nanocolloids [5,25], are negligible in the present kind of samples [14][15][16]), owing to the dominant opto-thermal effect and the reduced size of the nanoparticles in the BGN; optical trapping on small particles, in fact, tends to be proportional to their volume [55].…”

“…Since the Kerr-like (cubic) optical nonlinearity of nanocolloids can be either positive (focusing) or negative (defocusing) depending on the NP size and the wavelength of light, the generation of bright or dark spatial solitons has been pursued with them, as well, using pulsed or continuous-wave (CW) excitations [5,13]. The availability of such assortment of tunable all-optical materials has furthered all-optical circuits inspired by the "light guiding light" paradigm, whereby control beams are employed to switch, guide and/or modulate information-carrying wavepackets in photonic networks based on solitary waves and their interactions [17][18][19][20][21][22][23][24][25][26][27].…”

Resonant Optical Nonlinearity and Fluorescence Enhancement in Electrically Tuned Plasmonic Nanosuspensions

“…[6][7][8][9][10][11][12] Recently, plasmonic nanosuspensions are found to have superior performance, as compared with their dielectric counterparts, in demonstrating tunable optical nonlinearities that support guiding and self-trapping of light beams. [13][14][15][16][17][18][19][20][21] Robust soliton-like propagation of light over a long distance of several centimeters has been observed due to an effective cubic-quintic-like plasmonic resonant nonlinearity, which would otherwise be impossible in such highly scattering media.…”