Research Center of Ultrafast Science

Research Area: Ultrafast Spectroscopy
Status: Finished
Project leaders: Othonos, Andreas
Members: Alexandros Emporas
Haralambos Tsangaris
Loukas Loumakos
Demetra Tsokkou
Emmanouil Lioudakis
In cooperation with Nanowires
Proposed start date: 2004-01-01
Proposed end date: 2008-02-01
Funded by: Research Promotion Foundation
Funding: 470000.00 EUR

With the implementation of this research proposal the University of Cyprus and in particular the Department of Physics has developed a modern research laboratory in ultrafast science having a state of the art research equipment and as a result having research collaborations with Research Center and Universities worldwide. The infrastructure research project provided the funding for purchasing and installing an ultrafast laser amplifier which is able to generate 45 fs pulses with center wavelength at 800 nm and energy of 0.5 mJ at a repetition rate of 5kHz. The ultrafast amplifier system consisted of an Optical Parametric Amplifier for the generation of a particular laser wavelength using non-linear crystals. The Research Center of Ultrafast Science makes use of pump-probe techniques for the characterization and study of the optical properties of various novel material with temporal resolution of femtoseconds. These time scales have allowed the detail study of material such as semiconductors and polymers giving an important input to the technology of the future.

Description:

For the characterization of the optical properties of semiconductors and polymers involved in this research program we have constructed a high temporal resolution pump-probe optical setup to measure the time resolved reflectivity and transmission with the resolution of femtoseconds. The shape of the signal provides information regarding the electronic and optical changes the material has undergone following short pulse excitation. One of the advantages of the pump-probe techniques utilized in this research project is the ability to select the wavelength of the pump pulse using the Optical Parametric Amplifier and the generation of white light. The ability to control the pump and probe wavelength allows one to obtain a better understanding of the various energy states and their relaxation mechanisms. Furthermore, we have also constructed an optical pump probe setup for studying samples with micrometer resolution. This optical setup is almost identical to the previous described optical pump-probe setup with the difference been the focusing optics, whereby a set of focusing lenses provide the ability of focusing the excitation and probing beams with micrometer resolution. This particular optical setup maybe combine with a self-control pulse shaping system to further increase its capabilities.

For the study of the non-linear properties of materials, we have constructed a z-scan optical setup. In this setup the sample moves along the axis of transmission (z-axis) close to the focusing point of a converging lens with a linear translation stage which is control through a computer via the program LabView. Measurements of the transmitted intensity as a function of the position from the focus point of the lens provide information on the non-linear index of refraction and the non-linear absorption coefficient of the material under studied.

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