Title :
A study of waveguide modulation by excitonic screening
Author :
Tombling, C. ; Stallard, M.M. ; Roberts, J.S.
Author_Institution :
Univ. Coll. London, UK
Abstract :
Reports a GaAs-AlGaAs single quantum well waveguide device which uses quenching of excitonic absorption and can provide the high contrast absorption modulation, low insertion loss and low voltage operation desirable for systems applications. The device operates in depletion mode which favours high speed modulation. Excitonic absorption, normally observed at the quantum well band edge, can be quenched by the presence of free carriers in the quantum well sub-band. The presence of electrons in the well inhibits excitonic absorption by band filling effects. In the device described electrons are provided by an n+ doped region adjacent to the quantum well. This fills the sub-band with carriers, ensuring that the modulator is initially in a low absorption state. The presence of a junction in the structure then allows a small reverse bias to influence the carrier density in the quantum well, hence enabling a modulation of the excitonic absorption
Keywords :
III-V semiconductors; aluminium compounds; electro-optical devices; gallium arsenide; optical modulation; optical waveguides; semiconductor quantum wells; GaAs-AlGaAs; depletion mode; high contrast absorption modulation; high speed modulation; low insertion loss; low voltage operation; quenching of excitonic absorption; single quantum well waveguide device; waveguide modulation by excitonic screening;
Conference_Titel :
Heterojunction and Quantym Well Devices: Physics, Engineering and Applications, IEE Colloquium on
Conference_Location :
London