SIMULATION OF ULTRAFAST FIELD-EMISSION PLASMONIC NANOANTENNAS FOR PHz PROCESSING OF OPTICAL WAVEFORMS This thesis project studies the behaviour of ultrafast nanoscale plasmonic electron emitting antennas in free-space and focuses on the design and optimization of coupling to waveguide modes for potential operation within an integrated photonics platform. The main aim of the device is to process impinging ultrafast optical pulses and to extract quantitative information on their features, in particular the carrier-envelope phase (CEP). The electron emitters consist of a series of electrically interconnected 20nm-thick Au antennas, shaped as isosceles nanotriangles, with the sharpest tip facing a perpendicular collector nanowire, at ~45nm distance.