Hannover 2010 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 21: Poster I
Q 21.58: Poster
Dienstag, 9. März 2010, 16:00–19:00, Lichthof
Femtosecond pulsed ultraviolet enhancement cavity as high power spontaneous parametric down conversion source — •Roland Krischek1,2, Witlef Wieczorek1,2, Akira Ozawa1, Nikolai Kiesel1,2, Patrick Michelberger1,2, Thomas Udem1, and Harald Weinfurter1,2 — 1Max-Planck-Institut für Quantenoptik, D-85748 Garching — 2Department für Physik, LMU München, D-80799 München
Current multi-photon entanglement experiments are mostly based on the process of spontaneous parametric down conversion (SPDC). Typically, the SPDC process is pumped by femtosecond ultraviolet (UV) pulses obtained from a frequency-doubled titanium-sapphire (Ti:Sa) laser at a repetition rate of about 80MHz. However, today’s pump sources suffer from weak pump powers (<2W) resulting in low multi-photon count rates. Here, we present a new setup to boost the multi-photon generation rate of SPDC experiments. For this purpose we introduce a femtosecond enhancement cavity in the UV to pump a non-linear crystal inside. The cavity enhances resonantly the frequency-doubled Ti:Sa pulses. We reach a maximal UV power of 7W at the repetition rate of the Ti:Sa laser (80MHz). We characterize the spectra of the intra-cavity laser pulses and estimate the pulse duration inside the cavity by interferometric autocorrelation. In addition, we show the multi-photon count rates as a function of the pump power, reaching an improvement of the six-photon count rates by two orders of magnitude. Our results pave the way to various applications not only in photonic quantum logic, but also in nonlinear optics research.