Two-photon absorption and blue-light-induced red absorption in LiTaO3 waveguides

Two-photon absorption and blue-light-induced red absorption (BLIRA) is demonstrated in lithium tantalate (LiTaO3) waveguides with ultrashort laser pulses. The blue transmission is modeled for hyperbolic-secant-squared pulses of blue light and is shown to be heavily attenuated by two-photon absorption. The blue light also generates traps for red light, which are absorbed through single-photon interactions. Over 50% red absorption is observed. The blue pulse energy dependence of BLIRA is shown to follow recent theoretical models that rely on two different physical mechanisms depending on the temporal overlap of the pump and probe pulses. The time dependence of BLIRA is explored experimentally and is shown to fit well to a stretched-exponential model. Finally, we investigate the effects of pulse shaping and find that, over our range of pulse durations, the amount of BLIRA is relatively insensitive to pulse shape. (c) 2006 Optical Society of America.