LiNb MZM, is a dual electrode MZM, usally biased at quadrature. For your analysis, you can keep the vlotage of switching equal to 4 volts and bias voltage equal to 2 volts. this will make MZM perform in linear region.
Besides, try reading more papers on MZM. This will give you an insight of the parameters and their values to be choosen depending upon your application.