"An Adaptive Mid-infrared Ultrashort Pulse Source for Applications in Coherent Control"
Speaker: Hazel Hung, University of Southampton - ORC
Date: 3 October 2008
Time: 2pm
Venue: Building 46, Lecture Theatre C
Abstract:
An adaptive mid-infrared (MIR) ultrashort pulse source is investigated for application to the coherent control of molecules. The adaptive MIR pulse shaper is presented as a feasibility study in this talk. It involves shaping a near-infrared (NIR) pulse using a spatial light modulator in a phase-only pulse shaper. The shaped NIR pulse is then transferred to the MIR via a synchronously pumped optical parametric oscillator (SPOPO), which is consequently measured using a nonlinear detector whose signal is used as the feedback parameter to be optimised. Using a global optimisation algorithm, initial experiments demonstrated adaptive MIR pulse shaping of picosecond pulses, achieving pulse compression and double pulse generation. The transfer of the pulse shape from the NIR to the MIR in the SPOPO however, is non-trivial and is discussed in detail.
The investigation then progresses to the femtosecond regime where the demonstration of coherent control experiments becomes more accessible. Using a fibre-based chirped pulse amplification system, which is an attractive pump source for the SPOPO, adaptive pulse shaping is demonstrated, showing significant improvement in the quality of the 500 fs source at high pulse energies of 65 μJ, as a result of the learning loop.