Mach-Zehnder Modulator arm-length-mismatch measurement technique

This paper describes a robust measurement technique for determining the effective length mismatch of the two arms of a Mach-Zehnder modulator (MZM), based on its broad-band filter characteristics. The proposed method involves measuring the Vπ(λ), n(λ), and transfer function of a modulator at various externally applied bias points. This mismatch measurement technique is applied to a packaged polymer rib waveguide MZM, and it is shown that it has an arm-length mismatch of 1.9 μm. Poling-induced writing is then proposed as a fabrication technique that can consistently produce polymer MZMs with arm-length-mismatch values less than 2 μm.