Title: Development of an ultra-short terahertz source and application to molecular processes

Project: Terahertz waves (THz) have many applications ranging from imaging spectroscopy, near-field microscopy, opto-electronics, nonlinear optics and plasma physics. In particular, the ultrashort pulses in the terahertz domain (wavelength of around 0.3 mm, pulse duration of about one picosecond) have applications such as time-resolved spectroscopy for the study of vibrational modes and rotation of molecules or the measurement of the carrier lifetime in semiconductors. This type of pulse can also be an effective way to control and/or measure the orientation and alignment of molecules. The research team "Femtosecond Lasers and intense process" (PFL) is developing a system for generating terahertz pulses from a laser system emitting femtosecond pulses. It is based on the generation of plasma in a gas with a two-color pulse (800 and 400 nm). The generated THz pulses have duration less than a picosecond and a spectral range covering approximately 0 to 4 THz. The peak electric field is in the range 10 to 100 kV / cm. The generation device will be supplemented by an electro-optical device to measure the pulse shape in the time domain and also to measure the effects induced in molecules.The objective of the project is the completion of this broadband terahertz source (optimization and accurate characterization of terahertz pulses) and its application to molecular processes. The expected results relate firstly to optimization of orientation and alignment of molecules and also control of their movement (vibration/ rotation) by shaped pulses.The first experiment will be the orientation of polar molecules with these THz pulses in the gas phase. Other applications will then be considered, as the control of aligned and oriented molecules with shaped pulses. In the latter case, the pulse shaping will be produced by spectral modulation of the initial infrared femtosecond pulse with traditional modulation techniques based on liquid crystal devices.

The position (one year contract) is available from now and the contract should start before end of december 2015.

Contact: Bruno Lavorel bruno.lavorel@u-bourgogne.fr