Clarification of the Change in the Extinction Characteristics of an InP-Based Mach–Zehnder Modulator

The stability of the extinction characteristics of an InP-based Mach-Zehnder modulator is clarified in detail. The changes in the half-wavelength voltage (Vπ) and null point voltage (Vnull) are investigated under long-term high-temperature aging tests. The time correlations with the change in Vπ and Vnull are different from each other. By using a statistical treatment of the Weibull distribution, the degradation modes of the changes in Vπ and Vnull are clarified as a wear-out failure and an early failure, respectively.