Fixing experiments have been carried out in undoped alpha-phase proton-exchanged LiNbO3 waveguides at room temperature and 110°C. Above room temperature, the recording kinetics of the diffraction efficiency exhibits a maximum eta_max and then decays to zero. Upon raising the temperature, etamax decreases and the associated rise and decay times become progressively shorter. After fixing at 90°C and subsequent optical developing at room temperature, the developed value rises up to eta_dev approximately 2.5 eta_max, showing a lifetime of a few hours in the dark and a few days under homogeneous illumination. Time constants for recording, dark decay, and developing have been measured as a function of temperature. Experimental dependences are reasonably simulated by using the standard model for fixing with the same parameters as with bulk LiNbO3, except the electron thermal ionization rate and the proton concentration, which are much greater in alpha-phase guides.
© 2005 Optical Society of America
(130.3130) Integrated optics : Integrated optics materials
(130.3730) Integrated optics : Lithium niobate
(190.4400) Nonlinear optics : Nonlinear optics, materials
(190.5330) Nonlinear optics : Photorefractive optics
Gonzalo de la Paliza, Jesús Carnicero, Angel García-Cabañes, Mercedes Carrascosa, and José M. Cabrera, "Photorefractive fixing phenomena in alpha-phase proton-exchanged LiNbO3 waveguides," J. Opt. Soc. Am. B 22, 2229-2236 (2005)