Geometry Dependence of the Field-Induced-Guide/Antiguide Modulator

Using the field-induced-guide (FIG) concept [1], guide/antiguide modulator with on/off ratio larger than 22dB, and optical bandwidth larger than 0.55µm has been reported [2]. The device is formed with a central guide sandwich between two antiguides. For the on-state, a guide situation is created, and the input light will be confined and propagated in the central guide region. For the off-state, a antiguide situation is created, and the input light will be diffracted out of the central guide region [2]. It is obvious that the performance of the guide/antiguide modulator depends upon the geometrical dimensions of the gap G between the guide and antiguide electrodes, the active region length L, and the central guide width W. In order to understand the geometric dependence of the modulator, devices of different dimensions have been investigated, and both calculated and experimental results are reported here.