We analyzed two types of Mach-Zehnder plasmonic modulators on a silicon-on-insulator platform with a different furan-thiophene chromophore electro-optic polymer to compare to other reports. The metal-taper coupling structure and the metal-insulator-metal cross section in our design have been optimized based on the new material parameters. According to the simulation result, a modulator with a slot width of 50 nm and an on-off voltage of V pi = 20 V can be 21 mu m long, leading to a total modulator loss of 15 dB, which is comparable to previously reported devices. (C) 2017 Optical Society of America