PhD Defense of Róbert HORVÁTH

Abstract:
LesFiber optics, photonic and RF technologies will be at the core of next generation communication networks, while the carrier frequencies are moving into the millimetre wave range (30GHz – 300 GHz). Despite the use of high carrier frequencies, these transmission systems still require the detection and downconversion of modulated data-streams into the baseband for signal processing.
In this thesis we are proposing an optoelectronic heterodyne mixer system, based on a single device, for photonic assisted processing of data transmitted in a millimetre wave telecommunication link. The proposed scheme is a feasible solution for mixers at the receiver side of a Radio-over-Fibre network wireless link. The system is working in the 1.5 μm wavelength range and taking advantage of the ultrafast properties of an InGaAs photoconductive switch, in combination with a semiconductor mode-locked laser.
The characterization of the switch showed an ultrashort photocarrier lifetime of 1.2 ps, which ensures its high bandwidth and ability to work in the millimetre wave range.
System characterisations obtained a relatively flat response both in the electrical and optical domains up to 164 GHz. We demonstrate the optoelectronic mixer system performance through the downconversion and demodulation of a 2 Gbit/s QPSK modulated data-stream.
Ultrafast photoswitches are also potential candidates as samplers in Analog-to-Digital Converters. Finally, an experimental study is given to show the InGaAs photoswitch potential in such devices.
 

• Jean-François ROUX - Supervisor
• Anne-Laure BILLABERT - Reviewer
• Guillaume DUCOURNAU - Reviewer
• Jean-Emmanuel BROQUIN - Examiner
• Frédéric VAN DIJK - Examiner
• Cyril RENAUD - Examiner