Dresden 2011 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
DF: Fachverband Dielektrische Festkörper
DF 12: Poster
DF 12.6: Poster
Mittwoch, 16. März 2011, 15:00–17:30, P1
Photoacoustic absorption spectroscopy in lithium niobate crystals — •Niklas Waasem1, Stephan Fieberg1, Daniel Haertle1, Frank Kühnemann2, and Karsten Buse1 — 1Physikalisches Institut, Bonn, Germany — 2Physics Departmentof the German University, Cairo, Egypt
Lithium niobate is a highly transparent material that exhibits large non-linear optical coefficients, but for high-power applications even very small absorption coefficients can be a critical problem. Thus, determining the absorption spectra is a task of practical and scientific relevance. Existing methods of absorption spectroscopy fail either because they do not provide the necessary sensitivity of α < 10−4 cm−1 (grating absorption spectroscopy) or because of insufficient measuring speed needed for a wavelength scan (laser calorimetry). Therefore, we use a photo-acoustic approach. A sample is locally illuminated with nanosecond laser pulses, which heat and expand the exposed region. The resulting acoustic pressure waves are detected by fast and extremely sensitive piezo transducers. The amplitude of the measured signal is proportional to the product of pulse energy and absorption coefficient.