Beaming random lasers with soliton control

Abstract

Random lasers are resonator-less light sources where feedback stems from recurrent scattering at the expense of spatial profile and directionality. Suitably-doped nematic liquid crystals can random lase when optically pumped near resonance(s); moreover, through molecular reorientation within the transparency region, they support self-guided optical spatial solitons, i.e., light-induced waveguides. Here, we synergistically combine solitons and collinear pumping in weakly scattering dye-doped nematic liquid crystals, whereby random lasing and self-confinement concur to beaming the emission, with several improved features: all-optical switching driven by a low-power input, laser directionality and smooth output profile with high-conversion efficiency, externally controlled angular steering. Such effects make soliton-assisted random lasers an outstanding route towards application-oriented random lasers.

Mechanical analogies for nonlinear light beams in nonlocal nematic liquid crystals

“…While mathematical modelling of nematicons in nonlinear, nonlocal and saturable nematic liquid crystals has achieved substantial progress using these mechanical analogies, further work needs to be carried out to model more involved interactions and/or the interplay of various nonlinear responses in NLC, including e.g. symmetry breaking and bistability [73,74], interplay/competition of thermo-optic and reorientational phenomena [9,41,42,43,75], coexistence of electronic and reorientational responses acting on different time scales [76,77,78], reorientation in the presence of geometric phases [79,80], synergy of optical gain and scattering in doped NLC [81,82] and more.…”

“…We argue that these solutions should correspond to experimentally observed nematicons. Substituting the solitary wave form u(x, y, z) = ψ(x, y)e iσz in the electric field equation (82) leads to…”

Pump-Controlled Plasmonic Random Lasers from Dye-Doped Nematic Liquid Crystals with TiN Nanoparticles in Non-Oriented Cells

“…Over the past few decades, plenty of methods have been proposed for controlling the performance of random lasers [27][28][29][30][31][32][33]. Some deals with adjusting the scatterers, others depend on controlling the gain.…”

Electro-optic steering of random laser emission in liquid crystals

“…However, since selffocusing and soliton generation is available in nematic liquid crystals (NLC) when launching beams of arbitrary wavelengths, we introduced earlier a configuration able to substantially solve those issues with RL. A spatial soliton excited by a beam at a nonresonant wavelength (not absorbed), in fact, can effectively guide and collect the ASE produced by intense pump pulses resonant with the dye-doped mixture when launched collinearly with the pump [11][12][13]. The reorientational nonlinear response in the near-infrared (NIR) at 1064nm and the RL emission obtained by a green pump at 532nm with 6ns pulses at a 20Hz rep-rate were proven to allow for efficient lasing around 580nm, with a smooth transverse profile and directional emission supported by the soliton waveguide.…”