Minimisation of Parasitic Capacitance in Lumped-Element Electro-Absorption Modulators for High-Speed Optical Components

Abstract

This paper presents an investigation into the parasitic capacitance of an RF contact scheme for lumped-element EAMs. Test structures are fabricated to analyse this parasitic capacitance via S11 characterisation using a vector network analyser (VNA). Optimisations of the contact scheme lead to the parasitic capacitance being reduced to <10 fF. EAMs using this contact scheme are fabricated and characterised using S11 measurements. These S11 measurements are used to simulate S21 measurements, which predict a f3dB bandwidth of near 80 GHz using an equivalent circuit model.