Full-field characterisation of a novel femtosecond field synthesiser and applications in ultrafast science

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This project is concerned with the full-field, i.e. electric field waveform, characterisation of a novel, high-power, multi-colour femtosecond field synthesiser being developed in the Attosecond Laboratory (Physics Department, Imperial College). The synthesiser will be capable of generating femtosecond pulses with unprecedented control of the waveform through the coherent combination of phase-locked frequency channels all derived from a single laser source. A critical requirement is to fully characterise the synthsesier's output to allow its optimisation eg. using adaptive feedback to tailor the waveform for a particular application. Such full field characterisation of "arbitrary" waveforms of durations less than 20fs is extremely challenging. Conventional metrological techniques, such as FROG and SPIDER are not fit for this purpose. This project will explore complementary new approaches, including attosecond streaking, and techniques based on high harmonic generation (eg. the ARIES method). Consideration must be given to the measurement rate, which ideally should be as high as possible to allow close to real-time measurement of the waveforms (ie close to 1kHz). Once the waveforms are characterised the project will be ready to move to the next phase of work, which is the use of the waveforms for new applications in ultrafast science. These are likely to include optimisation of the flux of high order harmonic generation, the contrast improvement of attosecond x-ray pulses, and proof-of-principle experiments in atoms and molecules using ion time-of-flight and velocity-map imaging of electrons to measure the ionisation products.