Mainz 2017 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 24: Laser Development and Applications (Spectroscopy) (with Q)
A 24.7: Vortrag
Mittwoch, 8. März 2017, 16:00–16:15, P 5
Mid-IR laser-based FTIR imaging using a broadband fs laser source at 73 MHz repetition rate — •Florian Mörz, Rostyslav Semenyshyn, Tobias Steinle, Frank Neubrech, Andy Steinmann, and Harald Giessen — 4th Physics Institute and Research Center SCOPE, University of Stuttgart, 70550 Stuttgart,Germany
We demonstrate FTIR imaging of sub-wavelength layers of C60 and Pentacene at 7 µm using a broadband laser source. Imaging has been conducted by using aperture sizes as small as 10 x 10 µm with a 36x microscope objective. A 100 x 100 µm image of the molecule layers has been measured. A signal-to-noise ratio that exceeds common FTIR light sources, such as globars or synchrotrons, due to a several orders of magnitude higher brilliance has been observed. The applied laser source is based on the ffOPO system presented in [1, 2]. Here, a commercially available Yb:CALGO laser, providing 98 fs pulses at 73 MHz repetition rate, is used as a pump oscillator. The post-amplified ffOPO system converts the pump light to the 1.4 - 4 µm wavelength range. By difference frequency generation between signal and idler in AgGaSe2 up to 1 mW average power at 7 µm with 446 nm (93 cm−1) bandwidth (1/e2) is generated. The system exhibits superior long term stability over several hours. In conclusion, this laser based FTIR setup enables applications such as single nano-antenna measurements or protein sensing based on surface-enhanced infrared absorption (SEIRA).
[1] F. Moerz et al., Opt. Exp. 23, 23960 (2015)
[2] T. Steinle et al., Opt. Lett. 41, 4863 (2016)