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Details of Grant 

EPSRC Reference: EP/C009479/1
Title: An Intelligent Mid-Infrared Femtosecond Pulse Generator
Principal Investigator: Shepherd, Professor DP
Other Investigators:
Hanna, Professor DC Frey, Professor JG Richardson, Professor DJ
OConnor, Dr MV
Researcher Co-Investigators:
Project Partners:
Department: Optoelectronics Research Ctr (closed)
Organisation: University of Southampton
Scheme: Standard Research (Pre-FEC)
Starts: 01 September 2005 Ends: 28 February 2010 Value (£): 612,321
EPSRC Research Topic Classifications:
Chemical Biology Instrumentation Eng. & Dev.
Lasers & Optics Optoelect. Devices & Circuits
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:  
Summary on Grant Application Form
Coherent control (CC) of quantum phenomena offers exciting opportunities to physicists, chemists and biologists for the manipulation of solid-state and molecular systems by using shaped ultrashort laser pulses to excite the system. Theoretical design of optimal pulse shapes for molecular excitation is possible for only the simplest of molecular systems. So an emerging technique involves the exploitation of optimal control theory (OCT) to achieve optimal pulse shape, by using the experimental output in the optimization process. In this way, the molecule itself is used as an analogue computer to solve its own equations of motion in real-time. Although a limited number of successful demonstrations of adaptive, optimal CC (AOCC) have been carried out in the near-infrared (NIR), a practical method for generating broadband, adaptively shaped, femtosecond pulse systems in the mid-infrared (MIR) in order to directly control state-selective vibrational motion of molecules has been an elusive goal. Therefore, the development of 'intelligent MIR femtosecond pulse generators', which can adapt themselves to provide the optimum temporal and spectral characteristics required for a given application is both novel and very timely, greatly extending AOCC science and the study of femtosecond molecular dynamics.The instrument to be developed in this proposal is an intelligent MIR pulse generator capable of optimally exciting specific local molecular vibrations in order to drive large-scale collective motions of whole domains (conformational change). We will exploit the fact that high-fidelity, pulse-shaping schemes already exist for wavelengths ranging from the visible to the NIR, and will use this to control the shape of pulses at longer wavelengths via parametric frequency conversion. This will be accomplished by high-fidelity transfer of pulse shapes from the NIR pump to the MIR idler of a synchronously pumped optical parametric oscillator. In addition, we will implement 'closed-loop', adaptive control of the idler pulse shape using a learning algorithm for AOCC applications. This instrument will thus allow completely new experimental techniques as, for the first time, adaptively controlled arbitrary femtosecond pulse shapes will be available in the mid-IR. In this proposal, the instrument will be used to discover which pulse shapes create the largest vibrations and to use these optimal pulse shapes to drive conformational change in proteins and other large molecules of biological interest. Such conformational change is one of the most important features of current research in protein chemistry. The importance ranges from the role in the functioning of signalling proteins, to the harmful effect of prion proteins. Optimally shaped light pulses that interact with the protein offer the prospect of an experimental means of promoting conformational switching, with the different conformations being detected via fluorescence-based techniques. In order to deliver long-term value and wide future availability, this instrument will be based on a power-scalable all-fibre sub-100fs pump laser. This will enable high average powers (up to 100W) at high pulse repetition rates (50MHz) for low-noise and fast data acquisition, but with the flexibility to move to low repetition-rates and higher pulse energies for various possible future application regimes.In summary this proposal will deliver a novel instrument consisting of a fully engineered, flexible and power scalable, all-fibre femtosecond NIR pump source, with adaptively controlled femtosecond pulse shapes that are transferred to the 3-7 microns MIR spectral region, for novel experiments in conformational chemistry. It should also be noted that this work will quickly be followed by extension to other nonlinear materials, such as CdSe and GaAs, that will enable coverage of the spectral region out to 20 microns, again ensuring the long-term value of the instrument.
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Organisation Website: http://www.soton.ac.uk