Bias point thermal shift growth in Z-cut LiNbO/sub 3/ Modulators

Growth of a bias point thermal shift induced by dc bias in z-cut LiNbO/sub 3/ optical intensity modulators is quantitatively discussed from the standpoint of its impact on field service. During 20 years of device operation under a worst-case dc bias condition, the thermal shift slope grows almost symmetrically with respect to a bias polarity. An initial small thermal shift of around /spl plusmn/7 mV//spl deg/C (3/spl sigma/ distribution bounds) increases continuously over time with biased operation at 55/spl deg/C and approaches /spl plusmn/70 mV//spl deg/C after 20 years. This increased temperature sensitivity would generate approximately a 2-V bias point shift toward the bias rail when modulator is exposed to temperature variation from 55/spl deg/C to 25/spl deg/C.