Formation of two-dimensional channel waveguides and couples of such waveguides within a bulk of undoped lithium niobate has been experimentally demonstarated. Waveguide structures with a channel diameter of 23 μm have been formed by the bright spatial solitons obtained at the compensation of the diffraction divergence of light beams in the crystal due to the contribution of the pyroelectric effect into the nonlinear response. The light wavelength was 633 nm and the optical power was ranged from 1 μW to 1 mW in experiments. The total compensation of the diffraction divergence at uniform heating of the crystal sample to the temperature from 35 degrees.
42.65.Hw Phase conjugation; photorefractive and Kerr effects
42.65.Tg Optical solitons; nonlinear guided waves
Department of Microwave and Quantum Radio Engineering, Faculty of Engineering, Tomsk State University of Control Systems and Radioelectronics, Tomsk 634050, Russia.