An optical model of a transmission-type vertical-cavity electro-absorption modulator (EA) on Si/SiO 2 for highspeed intra/inter-chip interconnects is developed and analysed by the method of single expression (MSE). As an external radiation source a wideband light source is suggested for avoiding the problem of usage of Si emitter. Transmission properties of symmetrical structure of a modulator consisting of Si p-n junction embedded between Si/SiO 2 DBRs are analysed versus the values of imaginary part of p-n junction permittivity. Corresponding distributions of electric field amplitude and power flow density along the structure and surrounding half-spaces are presented for high and low transmission state. The transparency of the structure permits to have a cascade of modulators which can be installed in special trunks on chips for connection between different layers of an integrated circuit.

An optical model of a surface-normal electro-absorption (EA) modulator consisting of multiple-quantum wells (MQWs) embedded in an asymmetric Fabry-Perot (FP) cavity formed by high-reflective back DBR and moderate-reflective top DBR separated from MQWs at both sides by buffer layers is analysed numerically by the method of single expression (MSE). Reflectance of the modulator versus normalised thickness of the buffer layer is analysed for different alternation of quarter-wavelength layers of DBRs. Corresponding optical field patterns, distributions of power flow density and permittivity profiles along the modulator structures with different alternation of DBR layers are presented for low reflection state. The contrast of EA modulator with DBRs of high permittivity layers outermost depending on the operating wavelength is analysed for different values of imaginary part of a permittivity of quantum-well (QW) layers. In the result of modelling corresponding design rules for optimisation of surface-normal EA modulators are suggested.