title: Laser-pointer-induced self-focusing effect in hybrid-aligned dye-doped liquid crystals.
abstract: Nonlinear optics deals with phenomena where "light controls light"; e.g., there is mediation by an intensity-dependent medium through which light propagates. This field has attracted much attention for its immense potential in applications dependent on nonlinear processes, such as frequency conversion, multiple-photon absorption, self-phase modulation, and so on. However, such nonlinearities are typically only observed at very high light intensities and thus they require costly lasers. Here, we report on a self-focusing effect induced with a 1 mW handheld laser pointer. We prepared polymer-stabilized dye-doped liquid crystals, in which the molecular director orientation gradually changes from homeotropic at one surface to homogeneous at the other. This is referred to as hybrid alignment. In such films, the threshold intensity needed to form diffraction rings was reduced by a factor of 8.5 compared to that in conventional homeotropic cells, which enabled the induction of the self-focusing effect with a laser pointer.
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, R1-12, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, R1-12, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Aihara
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, R1-12, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Motoi
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Chemical Resources Laboratory, Tokyo Institute of Technology, R1-12, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Jun-Ichi
authors.initials: J
authors.lastname: Mamiya
authors.affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology, Korkeakoulunkatu 8, Tampere, 33720, Finland.
authors.forename: Arri
authors.initials: A
authors.lastname: Priimagi
authors.affiliation: 1] Chemical Resources Laboratory, Tokyo Institute of Technology, R1-12, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan [2] PRESTO, JST, 4-1-8 Honcho, Kawaguchi 332-0012, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shishido