Erlangen 2018 – wissenschaftliches Programm
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K: Fachverband Kurzzeit- und angewandte Laserphysik
K 3: Laser Systems and Applications
K 3.6: Vortrag
Dienstag, 6. März 2018, 15:30–15:45, MB HS
Cascaded regime of optical parametric amplification for efficient terahertz generation — •Giovanni Cirmi1,2, Halil Olgun1,3, Nicholas Matlis1, Michael Hemmer1, Koustuban Ravi1,4, Ivanka Grguras1, Yi Hua1, Anne-Laure Calendron1, Luis E. Zapata1, and Franz X. Kärtner1,2,4 — 1Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany — 2Physics Department and The Hamburg Centre for Ultrafast Imaging, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany — 3Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany — 4Research Laboratory of Electronics, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA
The efficient generation of multi-cycle coherent THz radiation is of primary importance to drive novel table-top FELs. We explore the cascaded OPA, a new regime of OPA. We start from a home-built Yb:YLF amplifier at 1017-1020 nm temporally chirped to 800-ps. We generate intra-band DFG in a PPLN crystal phase matched for 0.5 THz. The interaction of the IR pulses with the THz pulses produces several spectrally cascaded orders, allowing for the generation of THz radiation beyond the Manley-Rowe limit. This technique promises IR-to-THz conversion efficiencies in the order of 1-10%. After studying the system at room temperature, we explored the case of a crystal at 77 K, which provides much lower THz absorption. The experimental results support the theoretical findings, and reveal that improvements in laser bandwidth and dispersion will lead to the calculated efficiencies.