Hannover 2013 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 49: Ultrashort laser pulses: Generation II
Q 49.4: Vortrag
Donnerstag, 21. März 2013, 12:00–12:15, F 142
A broadband milliwatt-level mid-infrared source for near-field microscopy applications — •Robin Hegenbarth1, Andy Steinmann1, Sergey Sarkisov2, Stefan Mastel3, Sergiu Amarie3, Andreas Huber3, and Harald Giessen1 — 14th Physics Institute and Research Center SCoPE, University of Stuttgart, Stuttgart, Germany — 2Siberian Physical and Technical Institute of Tomsk State University, Tomsk, Russia — 3Neaspec GmbH, Planegg, Germany
We demonstrate the generation of broadband mid-infrared radiation by difference-frequency mixing of two signal wavelengths of a femtosecond dual-signal-wavelength optical parametric oscillator (OPO). The OPO is pumped by a mode-locked Yb:KGW laser with 530 fs pulse duration and 7.4 W average output power and employs a 1 mm long MgO:PPLN crystal with 31 µm poling period. With a total intracavity group delay dispersion equal to zero at 1740 nm wavelength the OPO generates two different signal wavelengths that are mixed in an extracavity GaSe or AgGaSe2 crystal. The polarizations of the OPO signals were adjusted to enable a type-II phase-matching process. This system generates up to 4.3 mW average mid-infrared power. Its spectra can be tuned between 10.5 µm and 16.5 µm (952 cm−1 - 606 cm−1) with more than 50 cm−1 spectral bandwidth. We combined this system with a scattering-type SNOM and show near-field spectra on gold and near-field scans of Si-doped GaN nanowires.