13 September 2016 Congratulations to New ICFO PhD graduate

Dr. Seth Cousin

Thesis Committee

Dr. Seth Cousin graduated with a thesis in ‘Towards the generation of isolated attosecond pulses in the water window’. Dr. Seth Cousin received his Master degree in Photonics from the joint program between UPC, UAB, UB and ICFO before joining the Attoscience and Ultrafast Optics research group led by ICREA Prof. at ICFO Jens Biegert. At ICFO, he centered his doctoral work on the extensive study and development of a light source capable of delivering the attosecond pulses in order to observe and study ultrashort physical processes. The work undertaken has culminated in the generation of the first isolated attosecond pulses in the water-window radiation range. Dr. Seth Cousin’s thesis, entitled ‘Towards the generation of isolated attosecond pulses in the water window’ has been supervised by Prof. Jens Biegert.


Attosecond science investigates the realm of processes that happen in fleetingly short passages of time. One attosecond to one second, is what one second is to the age of the universe! Advances in lasers and specifically ultra-short pulsed lasers have opened the door to this extreme frontier of physics. In this thesis I will describe what is required from a laser system in order to access these time scales. The stringent requirements needed motivated us to extensively study, model, redesign and then finally rebuild our laser system making it capable of delivering the necessary laser pulses. Characterisation of these types of laser pulses is essential in making them usable in the pursuit of a fundamental understanding of ultrashort physical processes. Two new characterisation techniques have been developed to add to the suite of tools available to the scientific community to achieve the complicated goal of characterising femtosecond laser pulses. To jump from the femtosecond regime to the attosecond regime, high harmonic generation is currently the defacto method of getting there. I will give a detailed description of our high harmonic beamline, which ultimately is used to perform the first water-window radiation range spectroscopy from a high harmonic source. Intrinsic to the radiation generated for spectroscopy is the sub-femtosecond temporal structure of the radiation. Temporal characterisation of attosecond pulses is traditionally done using the attosecond streaking technique however until now, this technique has not been used in the water-window. X-ray pulses possessing our ultra-broad bandwidth and central photon energy are unprecedented, making this the first time that a streaking experiment is done in this regime.

Thesis Committee

Prof Giuseppe Sansone, Politecnico Di Milano
Prof Ramon Vilaseca, UPC
Prof Simon Hooker, Clarendon Laboratory
Prof. Markus Drescher, University Hamburg