Reversibly Trapping Visible Laser Light through the Catalytic Photo-oxidation of I– by Ru(bpy)32+
journal contributionposted on 01.04.2016, 00:00 by Derek R. Morim, Ignacio Vargas-Baca, Kalaichelvi Saravanamuttu
A Gaussian, visible laser beam traveling in a hydrogel doped with NaI and Ru(bpy)3Cl2 spontaneously transforms into a localized, self-trapped beam, which propagates without diverging through the medium. The catalytic, laser-light-induced oxidation of I– by [Ru(bpy)3]2+ generates I3– species, which create a refractive index increase along the beam path. The result is a cylindrical waveguide, which traps the optical field as bound modes and suppresses natural diffraction. When the beam is switched off, diffusion of I3– erases the waveguide within minutes and the system reverts to its original composition, enabling regeneration of the self-trapped beam. Our findings demonstrate reversible self-trapping for the first time in a precisely controllable, molecular-level photoreaction and could open routes to circuitry-free photonics devices powered by the interactions of switchable self-trapped beams.