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| Identifier |
000398736 |
| Title |
Ultrafast opto-acoustic processes and devices |
| Alternative Title |
Υπερταχείες οπτο-ακουστικές διεργασίες και διατάξεις |
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Author
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Παπαδοπούλου, Ελισσάβετ Α.
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Thesis advisor
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Τζωρτζάκης, Στυλιανός
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Reviewer
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Ρακιτζής, Πέτρος
Λουκάκος, Παναγιώτης
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| Abstract |
Picosecond Laser ultrasonics is the study of the high frequency acoustic pulses which are generated in a medium and detected by ultrashort optical pulses. When an optical pulse illuminates a surface of a solid, some of its energy is absorbed and converted to heat. Heat will cause a temperature rise of the lattice, leading to a thermal stress which gives a strain pulse. The strain will cause a perturbation in the dielectric constants and to the position of the interfaces, which in its turn will affect the reflectivity of the incident laser pulse. The frequencies of the generated acoustic pulses are in the range of a few GHz up to THz. Due to the small acoustic wavelength in the nanometer scale, picosecond ultrasonics are ideal to investigate very thin films and nanostructures.
In this thesis there will be a mathematical description of the mechanisms that take place in solid materials when acoustic pulses are generated. A description of how these acoustic pulses affect the optical characteristics of the material will be also made. A method called layer-multiple-scattering method will be analyzed, as it is a very helpful tool to simulate and compute the effect of the acoustic pulse traveling inside a medium considering the optical scattering between interfaces of multilayered materials. Some results of simulations made will be included. Afterwards there will be a detailed description of the used experimental set-up in order to measure the optical changes caused by the acoustic pulse. Some experimental measurements will be presented and analyzed.
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| Language |
English |
| Subject |
Optoacoustics |
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Picosecond unltrasonics |
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Pump-probe |
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Διέγερση- ανίχνευση |
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Οπτοακουστικές διεργασίες |
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Πικοσέκοντ υπέρηχοι |
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Υπερτάχεις |
| Issue date |
2016-03-18 |
| Collection
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School/Department--School of Sciences and Engineering--Department of Physics--Post-graduate theses
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Type of Work--Post-graduate theses
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| Views |
575 |
Ultrafast opto-acoustic processes and devices
