Bandwidth Optimization for Mach-Zehnder Polymer/Sol-Gel Modulators

We demonstrate that the EO modulation response linearly decreases (dB scale) with respect to the modulating frequency, with an extremely small deviation of less than 1.5 dB, up to a limit of 67 GHz, as measured by an optical component analyzer. The measured bandwidth of the EO response is wider than 67 GHz and was extrapolated to 120 GHz. This study demonstrates a new optimized broadband optical modulator with low half-wave voltage and low optical loss. The dielectric constant of each material in the modulator is accurately measured by comparing the electrical transmission and reflection parameters for the RF high-speed coplanar electrode deposited on each layer with theoretically obtained values. The electrical transmission bandwidth for the optimized RF electrode is measured up to a limit of 110 GHz by a vector network analyzer and then extrapolated to a 6-dB bandwidth of 130 GHz based on the experimental parameters. The product of the half-wave voltage and electrode length is 1.8 V-cm for dual-drive operation. The in-device EO coefficient is 160 pm/V at 1.55 μm. The product of the half-wave voltage and loss is 10.8 V-dB.