SUPPRESSION OF CROSSTALK DRIFT IN TI-LINBO3 WAVE-GUIDE SWITCHES

DC drift characteristics wth short relaxation times (typically 20-30 s) of LiNbO3-based electrooptic switches are reported for use at the wavelength of 1.3 μm. The switch elements are evaluated without oxide buffer layers to focus on the substrate. Sputtering etching of more than 20 nm of the substrate surface after waveguide fabrication results in a remarkable suppression of the drift: drift-induced crosstalk of below -25 dB has been achieved. The sputtering process also reduces the range of scatter of voltage drift among four switches fabricated on a single substrate. With data on the capacitance and resistance between a pair of electrodes, the above effects are attributed to the removal of the surface layer by sputtering.