REFRACTIVE-INDEX FLUCTUATIONS IN DEFORMED TI-LINBO3 WAVE-GUIDES DUE TO SIO2 OVERLAYER DEPOSITION

During the fabrication process of Ti:LiNbO3 optical modulators, the de formation into a convex configuration of the LiNbO3 wafer occurs after the deposition of the micrometer-thick SiO2 buffer layer. This deform ation remains in the modulator chip and possibly generates the strain in the waveguides. The strain induced change of refractive index (DELT An) in the waveguide is estimated from consideration of the piezo-opti c effect. This DELTAn is on the order of 10(-5) and is close to that d ue to the electro-optic effect. The corresponding optical phase retard ation is in agreement with measured values.