Characterisation of optoelectronic devices for the generation and detection of picosecond electromagnetic pulses

Abstract :
This seminar focuses on the characterization of devices (electrical circuits incorporating photodetectors) based on fast carrier-recombination semiconductors (e.g., Gallium Arsenide - GaAs). These devices are designed to generate and detect electromagnetic pulses in the picosecond/THz range. To probe these ultrashort signals, we use a pump-probe technique relying on femtosecond optical pulses. The experimental setup will be described, with an emphasis on key parameters such as beam size and the optical delay line. We will then discuss novel device architectures, including pillar-shaped structures (to enhance efficiency) and the integration of alternative materials (to reduce fabrication costs). Finally, we will present our recent work on shaping the generated electrical pulse through controlled stretching of the optical pump using a grating-based temporal stretcher, and its impact on the resulting waveform