GaAs MMIC prototypes and Radio-over-Fibre modulating devices

GaAs MMIC prototypes:

Simple GaAs MMIC prototypes have been designed and experimented with the purpose to set up and refine both the design tools and the test and measurement facilities. The chips have been manufactured by the Gec-Marconi foundry using the F20 process.

Radio-over-Fibre modulating devices

Radio-over-Fibre (RoF) networks integrate optical fibre backbones and wireless cellular networks to provide broadband services to mobile, nomadic and fixed users. To generate and distribute RFmodulated optical signals, two schemes are used: direct modulation schemes, where a semiconductor laser is directly intensity-modulated by the RF-signal, and external modulation schemes, where the optical carrier generated by the laser is subsequently modulated by the RFinformation through an electro-optical modulator. The main modulating devices of such schemes have been analysed and modelled:

• the optical behaviour of an electro-absorption modulator has been analysed by using the Compact-2D-FDTD method;
• a circuit model has been developed and used to study the non-linear behaviour of directly modulated lasers.