Generalized Model of the Multi-Bit Electro-Optic Modulator

Abstract

New generalized model of the multi-bit electro-optic modulator for opto-electronic A/D converters is presented. The model allows to calculate frequency responses of the modulator and estimates modulating signal reflections and losses in the electrodes. Electrodes of the modulator could be connected to modulating signal source directly, using resistive voltage divider or matching coils. The mathematical basis of the model – system of linear equations. Coefficients in this system create tridiagonal matrix. Simple methodics, which allows to calculate primary parameters of the electrodes, is presented as well. Results of primary investigation of various types of electrode wiring and matching are also presented. It was shown, that modulator with traveling wave electrodes has the widest bandwidth – 2.8 times wider in comparison with bandwidth of modulator with unterminated electrodes. Bandwidth of the modulator with electrodes connected to modulating signal source using resistive voltage divider is at least 1.25 times wider than bandwidth of traditional modulator. Resistance and losses in the electrodes of the multi-bit modulator have significant influence on properties of modulator only for traveling wave type long electrodes.