Fast dynamic waveguides and waveguide arrays in photorefractive Sn(2)P(2)S(6) induced by visible light.

We report on dynamic waveguides and waveguide arrays induced beneath the surface of electro-optic Sn(2)P(2)S(6) crystals by visible light at 514 nm. The waveguide structures are generated by interband photoexcitation and drift or diffusion charge transport mechanism. These structures are probed nondestructively in the transverse direction with a beam at a longer wavelength. We measured the fastest formation of light induced waveguides in the visible up to now. The recording times are below 200 mus for intensities above 0.1 W/cm2. By interfering two light beams, dynamic waveguide arrays are generated with waveguide spacings of 7 microm. If an electric field is applied to the crystal, these arrays can be spatially shifted by 1.5 mum for an applied field of E(0) = 1 kV/cm.

Light deflection and modulation through dynamic evolution of photoinduced waveguides.

Light induced waveguides produced by lateral illumination of a hotorefractive crystal show a complex dynamic evolution upon removal of the sustaining applied electric field. Using this effect, deflection and modulation of the guided light is realized by taking advantage of the screening and counter-screening of the space charge distribution. The spot separation upon deflection can exceed 10 times the original waveguide width. Numerical simulations of the refractive index evolution and beam propagation show a good agreement with the observations.

Deep UV light induced, fast reconfigurable and fixed waveguides in Mg doped LiTaO(3).

Dynamic waveguides are induced beneath the surface of magnesium doped near-stoichiometric lithium tantalate by deep UV light at lambda = 257 nm using the interband photorefractive effect. The waveguides can be reconfigured in 10 ms at UV intensities of 100 mW/cm(2). We show the importance of the background illumination for the build-up of dynamic optical waveguides. We also present a new fixing process of the light-induced waveguide structures when the background light is absent. These quasi-fixed structures with dark decay times of several days are due to charges trapped in deep traps.

High-speed photorefraction at telecommunication wavelength 1.55 microm in Sn2P2S6:Te.

We demonstrated for what is the first time to our knowledge photorefractive two-wave mixing in a bulk ferroelectric crystal using cw light at the telecommunication wavelength 1.55 microm. In the Te-doped ferroelectric semiconductor Sn2P2S6 with absorption constant <0.1 cm(-1) at 1.55 microm, grating recording times of 10 ms and a two-beam coupling gain of 2.8 cm(-1) have been measured at 350 mW power (intensity 440 W/cm(2)) without a necessity to apply an external electric field. With a moving grating technique, a maximal gain of 6.0 cm(-1) has been obtained.