The photorefractive effect in titanium indiffused lithium niobate optical directional couplers at 1.3 µm

Abstract

In titanium indiffused lithium niobate directional couplers, photorefractive damage is seen at a wavelength of 1.3 μm when power levels in the guide exceed 25 mW ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5 \times 10^{4}</tex> W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) with time constants on the order of 100 h. Damage is not observed at lower power levels. Using a theoretical model based on the coupled wave equations and extrapolating the high power results, no significant degradation in performance is predicted for devices with less than 5 mW coupled into the waveguide.